M Stéphane

M Christophe Castel

Rapporteur Professeur

M Alberto Figoli

M David

M Philippe Moulin

Mme Audrey Soric

I

can even recall the moment that he answered my questions

INTRODUCTION 2

With the rapid development of technology and industry, pollution caused by gaseous and liquid pollutants is playing a vital role in climate changing, environmental disruption and human health damage. Pollutants capture, utilization, and sequestration strategy appear to be effective in decreasing the pollution level. Until now, pollution treatment processes mainly include recovery and destruction. Comparison of destructive processes, recovery processes are more competitive because both adsorbents and contaminants can be recaptured and recycled.

Among of the recovery processes, absorption is currently the most promising large-scale pollutants capture process due to its high capture efficiency, mature process, and good compatibility. While this process uses solvents to absorb the gaseous or liquid pollutants from feed streams in the absorption column, part of the solvents and its degradation products are discharged with the flue stream, causing new environmental pollution. In addition, there are still other major limitations in the pollutants capture processes based on absorption. Low absorption and desorption rates, solvent losses due to evaporation and the use of corrosive solvents are main obstructions. Recently, ionic liquids (ILs), as a feasible alternative for conventional organic solvents, show great potential in the separation processes. However, due to the unknown toxicity of ILs, many scientists have questioned the widespread use of ILs.

There are also some technical challenges on the use of ILs as solvents to absorption gaseous or liquid pollutants. For example, supported ionic liquid membranes tolerated ILs leakage on high pressure and unstable of long-time operation. The fact that capabilities of the new solvents (e.g. ILs) have not been tested sufficiently, implying that the design gaps have not had the chance to be explored and resolved. Especially, ILs absorption-membrane as an emerging process has proven its inefficiency to meet some of the treatment targets or/and sustain its performance over the long-time operation. It should mention that, for liquid pollutants absorption, separation of liquid contaminants from ILs remains a technical barrier.

Considering the above-mentioned issues, the goal of this study is to design a new hybrid process, the combination of advantages of membranes (modularity and compactness) and absorption processes (the use of ILs as solvents providing high selectivity and capacity), which cloud provide a guide of separation processes from lab-scale to industrial scale. Moreover, this concept identified the key parameters enhancing the separation performance. The hybrid membrane combinates ILs and a ceramic membrane applied to separate gas or liquid pollutants in a continuous green process. This membrane can be regenerated by a simple operation. This non-dispersive contacting device in which the support membrane does not separate gas/liquid phase and provide the high and effective contact area for mass transfer. To "built the ideal separation process", one has to consider the two main conditions for the good separation performance and regeneration of ILMs. One of them is related to the stability of the support membrane and implies the use of support membrane with very small pores that ensure that the target gas can pass through pores of the support membrane but the IL cannot. This enhances the stability of the ILM. A second condition is the physicochemical properties of the selected IL, including the high affinity to target gas or liquid and a relatively high viscosity to avoid liquid sorbents leakage. Furthermore, the achievement of ILMs long-term stability is also a target both on gaseous and liquid pollutants absorption.

Finally, this thesis focuses on following different objectives: i) develop and achieve the hybrid membrane-ILs process to selective absorbing gaseous or/and liquid pollutants; ii) study, evaluate and compare the removal performances of the ILM on different operating conditions;

iii) realize the regeneration of polluted ILM and the stability for long-term operation; iv) validate lab-scale results with an industrial length ILM; v) model results to better to understand the mass transfer of this hybrid process. This manuscript is divided into following five parts:

Chapter Ⅰ concerns the state-of-the-art. A general introduction of separation processes both recovery and destruction are presented, and comparison of the advantages and disadvantages of each separation processes is included. Especially, the detailly describe the separation performance of membrane process from membrane materials, internal structure and selectivity. The physicochemical properties of ILs and their application in separation processes are given. The highlighted introduction of the different configurations of ILs combined membranes are used in CO2 and volatile organic compounds (VOCs) separation, including supported ionic liquid membranes (SILMs), ionic liquids composite polymer membranes (ILPMs), ionic liquids composite mixed matrix membranes (ILMMMs), poly(ionic liquid)s membranes (PILMs), ionic liquid gel membranes (ILGMs) and ionic liquid membrane contactors (ILMCs). This chapter is a synthesis of a review published for VOCs and CO2 removal (Appendix 1).

Chapter II presents materials and methods. First, the concept of the ILM is described detailly including innovations, applications, and preparation methods. The properties of support porous membrane (a tubular ceramic membrane) are also exhibited. The ceramic membrane is more thermal and chemical resistant used in the gas-liquid interface. Second, global and branch descriptions of the experimental test bench. For the different applications, the process is adjusted depending on the actual separation process. Therefore, the humidity and VOCs removal processes are divided into descriptions. Third, gas detection devices (humidity and VOCs sensors) are introduced according to the detection mechanism, types, application conditions and sensor calibration. The effect of operating conditions on gas sensors is studied, and results are showing in Appendix 2. Forth, selection of the IL for different applications both humidity and toluene removal are realized. The screening principles and main physicochemical properties of ILs are analyzed based on the separation tasks. Finally, the different operating parameters testing are summarized and giving the analysis methods of experimental data.

Chapter III focuses on the separation of humidity from air. First, an IL-based filter was used to protect the metal oxide gas sensor from moisture. This experiment exhibited the IL could absorb humidity form a VOCs gas mixture and no secondary waste gases regeneration to disturb sensor response. Second, testing three different ILs to select an appropriate IL for an ILM preparation based on the humidity absorption capacity. Third, effects of different operating parameters on the ILM removal of humidity were discussed including gas flow rate, system pressure, relative humidity inlet, temperature, and positions of gas channels. Finally, according to these results, proposed operating conditions to regenerate the water-loading ILM was achieved. The removal performance of the ILM was evaluated after absorption-desorption.

Chapter IV exhibits the separation of VOCs (toluene) from air. First, investigation of two different ILs to select an appropriate IL for membrane preparation based on the toluene absorption capacity. Second, effects of different operating parameters on ILM removal of toluene were discussed including gas flow rate, system pressure, the concentration of toluene inlet and temperature. A large and industrial membrane was tested to remove toluene.

Moreover, the continuous treatment of toluene in industrial processes by connecting three industrial ILMs of in series are realized. Third, long-time operation and high absorption capacity also achieved on toluene removal. Finally, the toluene absorption capacity of the ILM was compared with recent publications.

Chapter V shows the gas sorption process of the ILM. First, the mass transfer process of the ILM and the factors that generate resistance to mass transfer were analyzed, which mainly used to decide the limiting factor during the whole gas sorption process Second, a two-step model for fitting and analyzing process of gas adsorption on the ILM. For example, the whole gas absorption process can be divided into two steps: surface adsorption and diffusion in bulk IL. Third, this two-step model was used to fit the experimental results of humidity and toluene removal with different operating conditions. Finally, the effects of different parameters on the simulated results of the 1D diffusion model (step 2) are discussed.

In the conclusions and perspectives, all the results obtained in this thesis are summarized, and some further studies about this subject are proposed.

Chapter I. State of the Art

Separation Processes

The development of global population and industrialization has resulted in lots of environmental problems with high negative effects on public health. Numbers of separation processes are already and wildly used to address environmental problems. Those separation processes are mainly divided into two parts depending on the destruction or recovery of the pollutants, as shown in Figure Ⅰ-1. The processes based on destruction including incineration [1][START_REF] Knox | An Overview of Incineration and EFW Technology as Applied to the Management of Municipal Solid Waste[END_REF][START_REF] Jabłońska | Zeolites Y modified with palladium as effective catalysts for low-temperature methanol incineration[END_REF][4], photocatalytic [START_REF] Qian | Carbon quantum dots decorated Bi2WO6 nanocomposite with enhanced photocatalytic oxidation activity for VOCs[END_REF][6][START_REF] Weon | Freestanding doubly open-ended TiO2 nanotubes for efficient photocatalytic degradation of volatile organic compounds[END_REF][START_REF] Suárez | From titania nanoparticles to decahedral anatase particles: Photocatalytic activity of TiO2/zeolite hybrids for VOCs oxidation[END_REF][START_REF] Héquet | Photocatalytic oxidation of VOCs at ppb level using a closed-loop reactor: The mixture effect[END_REF][START_REF] Qian | Mesoporous TiO2 films coated on carbon foam based on waste polyurethane for enhanced photocatalytic oxidation of VOCs[END_REF][11], catalysts [START_REF] Kamal | Catalytic oxidation of volatile organic compounds (VOCs) -A review[END_REF][START_REF] Liu | Catalytic removal of volatile organic compounds using ordered porous transition metal oxide and supported noble metal catalysts[END_REF][START_REF] Gallegos | Removal of VOCs by catalytic process. A study of MnZnO composites synthesized from waste alkaline and Zn/C batteries[END_REF][START_REF] Zhang | Low-temperature catalysis for VOCs removal in technology and application: A state-of-the-art review[END_REF], oxidation [START_REF] Piumetti | Mesoporous manganese oxides prepared by solution combustion synthesis as catalysts for the total oxidation of VOCs[END_REF][START_REF] Ji | Mesoporous TiO2 under VUV irradiation: Enhanced photocatalytic oxidation for VOCs degradation at room temperature[END_REF][START_REF] Yang | Deep oxidation of chlorinated VOCs over CeO2-based transition metal mixed oxide catalysts[END_REF][START_REF] Shu | Promotional role of Mn doping on catalytic oxidation of VOCs over mesoporous TiO2 under vacuum ultraviolet (VUV) irradiation[END_REF] and biological degradation [START_REF] Zhang | Current advances of VOCs degradation by bioelectrochemical systems: A review[END_REF][START_REF] Mudliar | Bioreactors for treatment of VOCs and odours -A review[END_REF][START_REF] Malakar | Comparative study of biofiltration process for treatment of VOCs emission from petroleum refinery wastewater-A review[END_REF][START_REF] Huang | Efficient degradation of gaseous benzene by VUV photolysis combined with ozone-assisted catalytic oxidation: Performance and mechanism[END_REF], and those based on recovery including adsorption [START_REF] Zhang | Adsorption of VOCs onto engineered carbon materials: A review[END_REF][START_REF] Sultana | Abatement of VOCs with Alternate Adsorption and Plasma-Assisted Regeneration: A Review[END_REF][START_REF] Xian | Competitive adsorption of water vapor with VOCs dichloroethane, ethyl acetate and benzene on MIL-101(Cr) in humid atmosphere[END_REF][START_REF] Zaitan | Application of high silica zeolite ZSM-5 in a hybrid treatment process based on sequential adsorption and ozonation for VOCs elimination[END_REF][START_REF] Gil | VOCs removal by adsorption onto activated carbons from biocollagenic wastes of vegetable tanning[END_REF][START_REF] Valenciano | A Critical Short Review of Equilibrium and Kinetic Adsorption Models for VOCs Breakthrough Curves Modelling[END_REF], condensation [START_REF] Kinder | Evaluating the impact of ambient benzene vapor concentrations on product water from Condensation Water From Air technology[END_REF][START_REF] Belaissaoui | Energy efficiency of a hybrid membrane/condensation process for VOC (Volatile Organic Compounds) recovery from air: A generic approach[END_REF], absorption [START_REF] Dumont | Equivalent Absorption Capacity (EAC) concept applied to the absorption of hydrophobic VOCs in a water/PDMS mixture[END_REF][START_REF] Ge | Fabrication of Functional Polyurethane/Rare Earth Nanocomposite Membranes by Electrospinning and Its VOCs Absorption Capacity from Air[END_REF][START_REF] Hariz | Absorption of toluene by vegetable oil-water emulsion in scrubbing tower: Experiments and modeling[END_REF][START_REF] Guillerm | Characterization and selection of PDMS solvents for the absorption and biodegradation of hydrophobic VOCs[END_REF][START_REF] Wang | Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal[END_REF][START_REF] Zhou | Experimental study on emission of VOCs from tanker using hollow fiber membrane absorption method with different absorbents[END_REF] and membrane processes [START_REF] Al-Gharabli | Enhancing membrane performance in removal of hazardous VOCs from water by modified fluorinated PVDF porous material[END_REF][START_REF] Ozturk | VOC separation using immobilized liquid membranes impregnated with oils[END_REF][START_REF] Zhou | High-performance PDMS membranes for pervaporative removal of VOCs from water: The role of alkyl grafting[END_REF][START_REF] Ge | VOCs Air Pollutant Cleaning with Polyacrylonitrile/Fly Ash Nanocomposite Electrospun Nanofibrous Membranes[END_REF][START_REF] Chen | Fabrication of porous copper/manganese binary oxides modified ZSM-5 membrane catalyst and potential application in the removal of VOCs[END_REF][43]. Compared to the destruction processes, the recovery processes are more economical because it is possible to regenerate both important compounds and value pollutants. The selection of an appropriate separate and control process is based on several factors: i) concentration and flow rate of gas treatment; ii) efficiency of gas destruction; iii) secondary waste generated or not; iv) additional treatment. Among all the factors, concentration and flow rate are the most important keys for selection of appropriate LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)]

Destructive Separation Processes

The operating temperature of the thermal oxidation process is from 700 to 1000 ℃ consuming large amounts of gas and energy to heat air and generate CO2 and NOx. This type of process can reach up to 95 to 99% of pollutant gas removal efficiency. The concentration range is from 100 to 200 mg L -1 and additional treatments are necessary [START_REF] Parmar | Emerging Control Technologies for Volatile Organic Compounds[END_REF]. This process can reduce the fuel consumption compared to the thermal oxidation process, because of the lower operating temperature. However, the major problem is catalyst deactivation specifically when the presence of water in the gas stream.

Biological treatments are kind of cost-effective methods to remove gases. This process can minimize hazardous media emission rather than with chemical or heat processes. However, they are limited by slow gas transfer from the gas stream to the liquid phase, which results in not effective for highly halogenated compounds. In addition, they are not allowing to recover or reuse the solvents.

Recovery Separation Processes

Adsorption process can remove one or more components from a mixture on a solid surface which based on intermolecular forces between gases and a solid sorbent [START_REF] Jarraya | VOC adsorption on raw and modified clay materials[END_REF]. Solid sorbents are significant for gas separation. Adsorption requires low energy compared to absorption and condensation processes. The efficiency should be improved from developing new adsorbents or modification of existing adsorbents so that the adsorbents can be operated at a higher temperature with enhanced capacity and increased selectivity. It is necessary to regenerate and reuse the adsorbent.

The condensation process involves compression and cooling of the gas mixture in several stages [START_REF] Mondal | Progress and trends in CO2 capture/separation technologies: A review[END_REF]. Condensation is the most efficient for pollutant gas treatment when the gases with a boiling point above 38 ℃ at high concentrations 5000 ppm. The separation is achieved by chilling or pressurization of the waste gas stream, and the driving force is oversaturation.

However, this process is difficult to apply to natural gas separation because there are in conjunction with other gases and during the cooling cause corrosion and fouling and plugging [START_REF] Yang | Progress in carbon dioxide separation and capture: A review[END_REF]. Normally, this process only can be used for special circumstances as an adjunct to other processes.

Membrane processes, with regards to gas capture, are classified into two types: gas separation membrane and gas absorption membrane [START_REF] Burdyny | Hybrid membrane/cryogenic separation of oxygen from air for use in the oxy-fuel process[END_REF]. For gas separation membrane, the separation is due to solubility or diffusivity of gas in the membrane and difference in partial pressure. For gas absorption membrane, a micro porous solid membrane is used as contacting device between gas and liquid flow. Gas absorption membrane provides a higher removal rate than the gas separation membrane due to high driving force. However, membrane processes can be regarded as highly gas capture processes only when the target gas concentration is higher than 20%. For target gas concentration lower than 20%, the membrane shows very low flexibility. Thus, hybrid processes or multiple stages are necessary to improve membrane separation.

Absorption process, including chemical and physical absorption, is widely used in gas separation. It is based on the "reaction" between the absorbate and solvent [START_REF] Choi | Removal characteristics of CO2 using aqueous MEA/AMP solutions in the absorption and regeneration process[END_REF]. Compared to physical absorption, chemical absorption shows the better result of removal efficiency on low concentration flue gases [START_REF] Rao | A Technical, Economic, and Environmental Assessment of Amine-Based CO 2 Capture Technology for Power Plant Greenhouse Gas Control[END_REF]. Enhance, a solution of two or more solvents as absorbents can exhibit excellent absorption performance in varying concentrations [START_REF] Glasscock | CO2 absorption/desorption in mixtures of methyldiethanolamine with monoethanolamine or diethanolamine[END_REF]. However, there are still several limitations that affect the efficiency of gas removal, including solvent degradation, corrosion and regeneration efficiency [START_REF] Damen | A comparison of electricity and hydrogen production systems with CO2 capture and storage. Part A: Review and selection of promising conversion and capture technologies[END_REF].

Among all the separation processes, absorption and adsorption can treat a larger range of concentration of pollutants with a larger flow rate than others. Moreover, absorption and membrane separations are deemed as the most widely studied and fastest growing separation processes for efficient pollutants treatment [START_REF] Castel | Membrane separations and energy efficiency[END_REF][START_REF] Cheng | Hybrid membranes for pervaporation separations[END_REF][START_REF] Buonomenna | Membrane processes and renewable energies[END_REF]. Table Ⅰ-1 gives the advantages and disadvantages of the above-discussed separation processes. According to the treatment of concentration, flow rate ranges and simple operations, membrane and absorption processes are selected for our study.

Table I-1. Advantages and disadvantages of separation processes [START_REF] Crespo | Membrane Processes in Separation and Purification[END_REF][START_REF] Pena-Pereira | The Application of Green Solvents in Separation Processes[END_REF].

Advantages Disadvantages

-energy consumption is generally low -no additives processes are required -up-scaling is easy -separation can be carried out continuously -membrane processes can easily be combined with other unit-operations -separation properties can be further improved -separation be carried out under mild conditions -flux decline due to concentration polarization and especially due to fouling results in a decrease of the volume flow through the membrane in time -relatively limited life-time -sometimes low selectivity

Membrane Processes

As above mentioned, combining absorption processes, which can treat relative larger concentration pollutants with a higher flow rate, and the membrane, which provides a mechanical and thermal support membrane, suggests a promising process for gas separation.

The membrane acts as a key role in membrane-based absorption processes. A membrane can provide an interface of two media include liquid solutions or gases [START_REF] Pena-Pereira | The Application of Green Solvents in Separation Processes[END_REF][START_REF] Tabani | Recent developments in green membrane-based extraction techniques for pharmaceutical and biomedical analysis[END_REF]. The separation performance of membranes is mainly governed by membrane materials, internal structure and selectivity [START_REF] Lee | Membrane materials for water purification: design, development, and application[END_REF][START_REF] Park | Maximizing the right stuff: The trade-off between membrane permeability and selectivity[END_REF]. Membranes are based on inorganic, organic and hybrid materials [START_REF] Lee | Membrane materials for water purification: design, development, and application[END_REF][START_REF] Liu | Membrane materials in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures -A review[END_REF].

Roughly spoken, membrane structures can be divided into two categories including porous and nonporous membranes [START_REF] Pena-Pereira | The Application of Green Solvents in Separation Processes[END_REF]. For selectivity, for example, suitability to transfer specific compounds from one medium pass through the membrane reach other media [START_REF] Crespo | Membrane Processes in Separation and Purification[END_REF][START_REF] Pena-Pereira | The Application of Green Solvents in Separation Processes[END_REF]. Inorganic membranes exhibit relatively high thermal, chemical and mechanical stability as well as their reusability, which attracted considerable attention [START_REF] Park | Maximizing the right stuff: The trade-off between membrane permeability and selectivity[END_REF]. Ceramic membranes are widely used because of their great fouling-resistance and stability, which allows the ceramic membranes used at high temperature and chemically harsh conditions where most polymeric membranes would not operate. In addition, some new materials are boosts, such as SiC [START_REF] Wei | Preparation of non-oxide SiC membrane for gas purification by spray coating[END_REF][START_REF] Yang | Preparation of highly stable porous SiC membrane supports with enhanced air purification performance by recycling NaA zeolite residue[END_REF][START_REF] Dabir | Fabrication of silicon carbide membranes on highly permeable supports[END_REF], inorganic nanoparticles [START_REF] Lv | Nanocomposite membranes of polydopamine/electropositive nanoparticles/polyethyleneimine for nanofiltration[END_REF][START_REF] Hu | Separation and antifouling properties of hydrolyzed PAN hybrid membranes prepared via in-situ sol-gel SiO2 nanoparticles growth[END_REF] and graphene-based materials [START_REF] Joshi | Precise and Ultrafast Molecular Sieving Through Graphene Oxide Membranes[END_REF][START_REF] Li | Ultrathin, Molecular-Sieving Graphene Oxide Membranes for Selective Hydrogen Separation[END_REF][START_REF]Large-area graphene-nanomesh/carbon-nanotube hybrid membranes for ionic and molecular nanofiltration[END_REF]. In many applications, composited two or more inorganic materials form a membrane to match the separation target. Organic membranes are mainly explored polymeric materials that offer a wide choice of structures and properties [START_REF] Crespo | Membrane Processes in Separation and Purification[END_REF][START_REF] Tabani | Recent developments in green membrane-based extraction techniques for pharmaceutical and biomedical analysis[END_REF]. It should be noticed that polymer membranes are suffering from a trade-off between permeability and selectivity [START_REF] Ilyas | Supported protic ionic liquid membrane based on 3-(trimethoxysilyl)propan-1-aminium acetate for the highly selective separation of CO2[END_REF]. Moreover, most of the polymeric membranes are hydrophobic, which leads to hard regeneration and relative narrow application ranges. Thus, surface modification methods are developed to address those problems, such as surface modifications [START_REF] Park | Nanocrack-regulated self-humidifying membranes[END_REF][START_REF] Cui | Bio-inspired fabrication of superhydrophilic nanocomposite membrane based on surface modification of SiO2 anchored by polydopamine towards effective oil-water emulsions separation[END_REF], plasma treatment [START_REF] Fu | Ultra-thin enzymatic liquid membrane for CO2 separation and capture[END_REF][START_REF] Zhao | Improved CO2 separation performance of composite membrane with the aids of low-temperature plasma treatment[END_REF] or mixed-matrix membranes [START_REF] Zimmerman | Tailoring mixed matrix composite membranes for gas separations[END_REF]. Inorganicorganic hybrid membranes introduce inorganic moieties into organic matrix systems what can enhance mechanical strength and separation efficient [START_REF] Kang | Free-standing, polysilsesquioxane-based inorganic/organic hybrid membranes for gas separations[END_REF][START_REF] Rybak | Metal substituted sulfonated poly(2,6dimethyl-1,4-phenylene oxide) hybrid membranes with magnetic fillers for gas separation[END_REF]. Researchers are believed that hybrid membrane exhibits thermal and chemical stability and filtration performance.

In general, there are two categories of membranes: porous and nonporous membranes, as shown in Figure Ⅰ-3. For porous membrane, pore size is often directly related to membrane separation efficient. Microfiltration membranes, pore size is between 0.1 to 1.0 um, are widely used for suspended solid particles and bacteria. The pore size of ultrafiltration membranes is from 10 to 100 nm, and they usually are used to separate proteins. Nanofiltrations with pore size with units of nanometers are mainly used for peptides, dyes, pharmaceutical compounds, and herbicides separation. Pore size below 1.0 nm induces reverse osmosis using dense membrane, which is most researched for salts and ions separation [START_REF] Crespo | Membrane Processes in Separation and Purification[END_REF][START_REF] Pena-Pereira | The Application of Green Solvents in Separation Processes[END_REF]. For nonporous membranes, there are dense and bulk liquid membranes. 3. Ionic Liquids (ILs)

Physicochemical Properties of ILs

Ionic liquids (ILs) are organic molten salts with many excellent properties [START_REF] Jordan | Biodegradation of ionic liquids -a critical review[END_REF][START_REF] Amde | Environmental Application, Fate, Effects, and Concerns of Ionic Liquids: A Review[END_REF][START_REF] Ghandi | A Review of Ionic Liquids, Their Limits and Applications[END_REF].

Besides, the alteration of cations and anions produces specific compounds for given applications [START_REF] Jadhav | Task-specific hexaethylene glycol bridged di-cationic ionic liquids as catalysts for nucleophilic fluorination using potassium fluoride[END_REF][START_REF] Patil | Tailor-made dicationic ionic liquid as a fluorescent sensor for detection of hydroquinone and catechol[END_REF]. ILs are regarded as green solvents because of their negligible vapor pressure. Therefore, they are non-flammable that can exclude the most uncontrollable and dreadful risks to human health and the environment. Certainly, these aspects make ILs safer and environmentally to replace traditional organic solvents. ILs have been got lots of attention because of their physicochemical properties and potential roles in sustainable development.

Specifically, room temperature ionic liquids (RTILs) are salts in liquid at room temperature [START_REF] Egorova | Fundamental importance of ionic interactions in the liquid phase: A review of recent studies of ionic liquids in biomedical and pharmaceutical applications[END_REF].

The most significant application is that RTILs as solvents to replace volatile solvents due to their excellent physicochemical properties. Furthermore, RTILs exist as a liquid at ambient temperatures due to their chemical structure. The anion and cation are chosen precisely to destabilize the solid-phase crystal.

Therefore, even though there are no set rules for making an IL, this can be achieved within ion structures by balancing ion-ion interactions. Structure and nanostructure control of IL properties [START_REF] Hayes | Structure and Nanostructure in Ionic Liquids[END_REF]. Two special types of mesoscale structures exist in the ILs system: i) hydrogen bond, ii) ionic cluster. The viscosity of ILs was effect by hydrogen bonds. For example, the strength of hydrogen bonds is determined items to improve the viscosity of pyridinium ILs [START_REF] Ma | Relationship between hydrogen bond and viscosity for a series of pyridinium ionic liquids: Molecular dynamics and quantum chemistry[END_REF]. Ionic clusters will influence the IL properties and behaviors including viscosity, dissolution and acidity or alkalinity [START_REF] Liu | Mesoscale structures and mechanisms in ionic liquids[END_REF]. The multiple combinations of cation/anion can lead to more than 100000 different ILs, each of them with specific physicochemical properties. In this case, ILs are also regarded as designer solvents. The cations are generally compositing organic compounds as ammonium, phosphonium, pyridinium or imidazolium (Figure I-4) with alkyl chains (Rn) [START_REF] Hallett | Room-Temperature Ionic Liquids[END_REF]. The anions of the ILs could be organics or minerals (Table Ⅰ-3). Usually, the physical properties were controlled by cations, and the anions reflect chemical properties [START_REF] Béguin | Carbons and Electrolytes for Advanced Supercapacitors[END_REF].

Based on steric hindrance, the cation/anion asymmetry and the alkyl chains length (Table Ⅰ -4) have dramatic effects on the melting point, which decrease with that parameter increasing [START_REF] Xing | Investigation of unique interactions between cellulose acetate and ionic liquid [EMIM]SCN, and their influences on hollow fiber ultrafiltration membranes[END_REF][START_REF] Hunt | Why Does a Reduction in Hydrogen Bonding Lead to an Increase in Viscosity for the 1-Butyl-2,3-dimethyl-imidazolium-Based Ionic Liquids?[END_REF]. The low melting point and the thermic stability (> 350 °C) allow the use of ILs in a large thermic operating range (300 -400 °C). The density of ILs except for the tetraalkyborates is generally higher than water. Moreover, the density decreases with the cation alkyl length increasing [START_REF] Endres | Air and water stable ionic liquids in physical chemistry[END_REF]. In addition, the density is also controlled by the anion. The viscosity of ILs is higher than organic solvents. When the cation alkyl length increases, the viscosity increases. [START_REF] Noda | Pulsed-Gradient Spin-Echo 1H and 19F NMR Ionic Diffusion Coefficient, Viscosity, and Ionic Conductivity of Non-Chloroaluminate Room-Temperature Ionic Liquids[END_REF]. ILs are considered as polar solvents and their polarity close to alcohols with short alkyl length [START_REF] Baker | Temperature-dependent microscopic solvent properties of 'dry' and 'wet' 1-butyl-3-methylimidazolium hexafluorophosphate: correlation with ET(30) and Kamlet-Taft polarity scales[END_REF]. Generally, the polarity can affect the solubility of ILs. The aromatic compounds are more than ten times the alkyl compounds.

CH3CO2 - OTs (= C6H5SO3 -) NTf2 (= N(SO2CF3)2 -) OTf (= SO3CF3 -) CTf3 (= C(SO3CF3)3 -) X (= F, Cl, Br, I) BF4 -, PF6 - Lewis Acid + X -

Applications of ILs in Separation Processes

However, several studies have underlined that there are some negative effects of ILs on the environment resulting in a limitation of their applications in the industry [START_REF] Costa | Environmental Impact of Ionic Liquids: Recent Advances in (Eco)toxicology and (Bio)degradability[END_REF][START_REF] Sintra | Ecotoxicological evaluation of magnetic ionic liquids[END_REF][START_REF] Sydow | Biodiversity of soil bacteria exposed to sub-lethal concentrations of phosphonium-based ionic liquids: Effects of toxicity and biodegradation[END_REF]. It is necessary to find a method to break this limit. Although, it is possible to change the ILs chemical compounds to reduce their environmental risks [START_REF] Bittermann | Assessing the toxicity of ionic liquids -Application of the critical membrane concentration approach[END_REF][START_REF] Grzonkowska | How the structure of ionic liquid affects its toxicity to Vibrio fischeri?[END_REF]. It will increase the difficulty to meet the given processes requirements with reduction of their hazard potential. ILs are not intrinsically green, but they can be made green, and their use in specific processes can lead to improvements that comply with the principles of green engineering. For example, the stability of the ILs into a supported media provides a promising way to realize the use of ILs with environmental damages reducing. ILs combine with membrane processes have been becoming a promising approach in separation fields in recent years. It can promote solvent properties of ILs and enhance membrane separation performances. In the past few years, many different types of membrane separation processes containing ILs have been studied. They are mainly focused on VOCs or CO2 removing. The problems and challenges in ionic liquid membrane separation processes are identified and discussed in the following parts of this chapter. This state-of-the-art is an extract from a review published and positioned in Appendix 1 of this manuscript.

Membrane Processes Containing ILs

ILs are made by associating large organic cations with a wide variety of anions. This results in a large variety of ILs which can be adapted to a given process. Combination of these features can bring new opportunities in the use of ILs-membranes and processes in gas separation applications [START_REF] Wang | The influence of various ionic liquids on the properties of SPEEK membrane doped with mesoporous silica[END_REF][START_REF] Wu | Membrane fouling in vacuum membrane distillation for ionic liquid recycling: Interaction energy analysis with the XDLVO approach[END_REF][START_REF] Fallanza | Comparison of Reactive Membranes Containing ILs in the Separation of Gaseous Olefin-Paraffin Mixtures[END_REF], which are energy-saving and environmentally friendly. In recent years, many studies focused on the use of ILs in membranes and membrane processes. Different types of membrane and membrane processes containing ILs are listed, discussed and compared, including supported ionic liquid membranes (SILMs), ILs composite polymer membranes (ILPMs), ionic liquids composite mixed matrix membranes (ILMMMs), poly(ionic liquid)s membranes (PILMs), ionic liquid gel membranes (ILGMs) and ionic liquid membrane contactors (ILMCs). For each configuration, advantages and disadvantages are presented and more especial for the treatment of VOCs and CO2, which are the most significant compounds treated.

Supported Ionic Liquid Membranes (SILMs)

Supported ionic liquid membranes (SILMs) are porous hydrophobic membranes impregnated with ILs [START_REF] Santos | Acetate based Supported Ionic Liquid Membranes (SILMs) for CO2 separation: Influence of the temperature[END_REF][START_REF] Ban | Confinement of Ionic Liquids in Nanocages: Tailoring the Molecular Sieving Properties of ZIF-8 for Membrane-Based CO2 Capture[END_REF][START_REF] Tomé | Cholinium-based Supported Ionic Liquid Membranes: A Sustainable Route for Carbon Dioxide Separation[END_REF]. They have been showing several potentials in different separation applications, such as organic compounds removing [START_REF] Oh | Understanding the pHresponsive behavior of graphene oxide membrane in removing ions and organic micropollulants[END_REF][START_REF] Hojniak | Highly Selective Separation of Carbon Dioxide from Nitrogen and Methane by Nitrile/Glycol-Difunctionalized Ionic Liquids in Supported Ionic Liquid Membranes[END_REF], separation of mixed gases [START_REF] Pizzoccaro-Zilamy | Initial Steps toward the Development of Grafted Ionic Liquid Membranes for the Selective Transport of CO2[END_REF][START_REF] Hassan Hassan Abdellatif | Grafting cellulose acetate with ionic liquids for biofuel purification membranes : Influence of the anion[END_REF][START_REF] Althuluth | Natural gas purification using supported ionic liquid membrane[END_REF] and vapor permeation [111][START_REF] Ansaloni | Influence of water vapor on the gas permeability of polymerized ionic liquids membranes[END_REF][START_REF] Sullivan-González | Hydrogen-bond acceptance's role in designing room temperature ionic liquid (RTIL) membranes for gas dehumidification, part I: Impacts on permeance and selectivity[END_REF][START_REF] Kudasheva | Dehumidification of air using liquid membranes with ionic liquids[END_REF]. Generally, the driving force is due to the concentration or pressure gradient between the feed and the receiving phase, which results in energy conservation [START_REF] Wang | Recent development of ionic liquid membranes[END_REF][START_REF] Noble | Perspective on ionic liquids and ionic liquid membranes[END_REF]. In addition, high selectivity and low solvent holding of SILMs are also attractive advantages. Whereas, the primary disadvantage is insufficient membrane stability for large scale and long-time operations, which has been proven by several studies [111,[START_REF] Wang | Recent development of ionic liquid membranes[END_REF][START_REF] Tomé | Ionic liquid-based materials: a platform to design engineered CO2 separation membranes[END_REF][START_REF] Liang | Composite ionic liquid and polymer membranes for gas separation at elevated temperatures[END_REF]. The selectivity of SILMs will be strongly decreased because ILs was pushed out of porous support with the over-time operation. For industrial application, the most important property is the process stability. In recently, most researchers focus on improving the stability of SILMs for long-time operation. The strategies to improve SILMs stability are mainly from the following three points: properties of the support membrane, viscosity of ILs and preparation ways. It is important for the stability of SILMs to choose a suited support membrane. Generally, the support membranes are including inorganic and polymeric membranes. For the inorganic membrane as a support membrane, ceramic membranes are the most widely used due to high mechanical strength and thermal stability. In this case, the SILMs with ceramic membranes as supports can be used at relatively high temperature and pressure of operations. For example, Karousos et al. [START_REF] Karousos | Effect of a cyclic heating process on the CO2/N2 separation performance and structure of a ceramic nanoporous membrane supporting the ionic liquid 1-methyl-3-octylimidazolium tricyanomethanide[END_REF] have developed a ceramic membrane with 1-methyl-3-octylimidazolium tricyanomethanide ( [Omim][TCM]), which was subjected to a cyclic heating process up to 453 K. Additionally, a thin ionic liquid membrane with ceramic support that can resist up to 55 bar transmembrane pressure, was presented by Kreiter et al. [START_REF] Kreiter | Pressure resistance of thin ionic liquid membranes using tailored ceramic supports[END_REF]. In addition, carbon materials are also a good choice for inorganic support in SILMs. Chai et al. [START_REF] Chai | Brick-and-mortar" synthesis of free-standing mesoporous carbon nanocomposite membranes as supports of room temperature ionic liquids for CO2-N2 separation[END_REF] According to research of Riso et al. [START_REF] De Los Ríos | A SEM-EDX study of highly stable supported liquid membranes based on ionic liquids[END_REF], they studied the Nylon membrane as a support based on three ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate

([Bmim][PF6]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]
) and 1-butyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]). As shown in Figure I-5, the feed and strip phases were separated by an organic membrane phase. They found that the mass of ILs retained in membrane pores was constant during operation. Cichowska-Kopczynska et al. [START_REF] Cichowska-Kopczyńska | Separation of toluene from gas phase using supported imidazolium ionic liquid membrane[END_REF] investigated the imidazolium ILs supported on PP. They found that maximum pressure possible to apply without membrane damage was 59 kPa. They also revealed that the thickness of PP support was higher after swelling ILs, which could change the structure of the polymer network and enhance its mechanical stability [START_REF] Cichowska-Kopczynska | Wetting processes in supported ionic liquid membranes technology[END_REF]. The mechanical properties of PVDF support on 1-ethyl-3-methylimidazolium ethyl sulfate ( [Emim][EtSO4])

and 1-ethyl-3-mwthylimidazoliun acetate ( [Emim][Ac]) were studied by Gomez-Coma et al.

[125], and these membranes showed better mechanical properties than others. Moreover, to improve the stability of SILMs, PVDF was also used as support [START_REF] Kim | Study on immobilized liquid membrane using ionic liquid and PVDF hollow fiber as a support for CO2/N2 separation[END_REF]. SILMs based on 1-noctyl-3-methylimidazolium hexafluorophosphate ([C8mim] [PF6]) and hydrophobic PVDF were synthesized, in which the ideal selectivity was improved even after 8 cycles under 298 K and 1.2 bar [START_REF] Cserjési | Study on gas separation by supported liquid membranes applying novel ionic liquids[END_REF]. Hanioka et al. [START_REF] Hanioka | CO2 separation facilitated by task-specific ionic liquids using a supported liquid membrane[END_REF] examined the long-term stability of a PTFE membrane supported n-aminopropyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

([C3NH2mim][NTf2]
). They found that membrane kept its permeability and selectivity under atmospheric pressure even after 260 days. Therefore, PS has been used to synthesize support membranes due to excellent mechanical strength, high thermal and chemical stability [START_REF] Korminouri | Surface modification of polysulfone hollow fiber membrane spun under different air-gap lengths for carbon dioxide absorption in membrane contactor system[END_REF][START_REF] Lu | Polysulfone-ionic liquid based membranes for CO2/N2 separation with tunable porous surface features[END_REF].

Ilconich et al. [START_REF] Ilconich | Experimental investigation of the permeability and selectivity of supported ionic liquid membranes for CO2/He separation at temperatures up to 125°C[END_REF] studied the stability of a SILM with 1-n-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Hmim][NTf2]), and a PS membrane used as a support.

They found that membrane was stable up to 398 K. Alkhouzaam et al. [START_REF] Alkhouzaam | High-pressure CO2/N2 and CO2/CH4 separation using dense polysulfone-supported ionic liquid membranes[END_REF] synthesized dense SILMs using PS as a support membrane. They investigated the applicability of these SILMs in industrial gas separation processes under high pressure. Respectively, the membrane showed In addition, the SILMs can tolerate higher transmembrane and pressure by choosing support with suitable pore sizes because ILs extrusion from the large pores of membrane could be mainly contributing to ILs loss of SILMs [START_REF] Close | CO2/N2 separations using nanoporous aluminasupported ionic liquid membranes: Effect of the support on separation performance[END_REF]. Some studies are suggested that supported membranes with pore size range from 100 to 200 nm are suitable for composed SILMs [START_REF] Wang | Recent development of ionic liquid membranes[END_REF][START_REF] Close | CO2/N2 separations using nanoporous aluminasupported ionic liquid membranes: Effect of the support on separation performance[END_REF]. Fatyeyeva et al. [START_REF] Fatyeyeva | Vapour sorption and permeation behaviour of supported ionic liquid membranes: Application for organic solvent/water separation[END_REF] observed that the presence of ILs affects the permeability of the membrane strongly by reducing the pore sizes. Besides, it should be noted that the high porosity of supports provides a more active surface area, which results in a stronger diffusion during the support membrane. However, the mechanical strength of the membrane will be decreased with increasing porosity.

Also, different preparation methods of SILMs affect stability. Preparation methods of SILMs fall into three main categories: immersion, vacuum, and pressure. For the immersion, porous support or substrate is soaked in an IL bath, and then the IL is filled into the pores of the support by capillary forces [START_REF] Wang | Recent development of ionic liquid membranes[END_REF]. This method is the easiest and available way to prepare a SILM. However, the SILMs prepared in this way have less stable. It means the IL within the pores of the supported membrane will be pushed out because of the transmembrane pressure.

Fortunato et al. [START_REF] Fortunato | Supported liquid membranes using ionic liquids: study of stability and transport mechanisms[END_REF] found that the immersion method was not suitable for high viscosity of ILs because capillary forces decrease with increasing viscosity of ILs. For the vacuum, IL was spread out the membrane surface by vacuum. Similarly, when the viscosity of ILs increases, the loss of ILs was increased for SILMs prepared by vacuum [START_REF] Hernández-Fernández | Preparation of supported ionic liquid membranes: Influence of the ionic liquid immobilization method on their operational stability[END_REF]. This phenomenon can be explained by the fact that ILs are on the external surface of the supported membrane by vacuum method. During operation, it is easy for ILs to break away from the support. For the pressure, IL was forced by certain pressure to get into the pores of supports. This method is suitable for high viscosity of ILs due to independence of ILs. Furthermore, SILMs by pressure method was verified by Hernandez-Fernandez et al. [START_REF] Hernández-Fernández | Preparation of supported ionic liquid membranes: Influence of the ionic liquid immobilization method on their operational stability[END_REF]. Recently, the new method (cold plasma) was used to treat SILMs. The loss of ILs by plasma treated was lower than the untreated membrane due to the higher affinity of the support and IL [START_REF] Dahi | Effect of cold plasma surface treatment on the properties of supported ionic liquid membranes[END_REF].

IL-Polymer Membranes (ILPMs)

ILs composite polymer membranes provide a successful method to solve the instability of SILMs [START_REF] Shalu | Thermal Stability, Complexing Behavior, and Ionic Transport of Polymeric Gel Membranes Based on Polymer PVdF-HFP and Ionic Liquid[END_REF]. The IL was stabilized into a polymeric membrane by entrapped it in the space of polymer chains or clusters [START_REF] Lu | Advanced applications of ionic liquids in polymer science[END_REF][START_REF] Dai | Combination of ionic liquids with membrane technology: A new approach for CO2 separation[END_REF], which provides a mechanically stable membrane as shown in Figure I-6. Although polymeric membranes exhibited excellent mechanical stability, which can overcome the main drawback of SILMs, it should be mentioned that PILMs already show a certain trade-off between permeability and selectivity for gas separation. Therefore, several studies were donated to find a solution to reduce the trade-off and to develop a desirable membrane. According to previous studies, the IL loading content and polymeric membranes affect the stability of ILPMs [START_REF] Sasikumar | Recent progress in ionic liquid membranes for gas separation[END_REF][START_REF] Fam | Improving CO2 separation performance of thin film composite hollow fiber with Pebax®1657/ionic liquid gel membranes[END_REF]. Mass transfer in ILs is much faster than in a solid polymeric matrix, resulting in higher gas flux and faster separation for ILPMs with higher ILs loading [START_REF] Dai | Combination of ionic liquids with membrane technology: A new approach for CO2 separation[END_REF][START_REF] Chen | PVDF/ionic liquid polymer blends with superior separation performance for removing CO2 from hydrogen and flue gas[END_REF]. In addition, the polymer matrix is more amorphous with the increase of ILs content which supports the enhancement of the permeability of gas species through polymers.

Furthermore, the stability of the polymeric matrix directly determines the operating pressure and temperature of the ILPMs [START_REF] Mannan | Synthesis, characterization, and CO2 separation performance of polyether sulfone/[EMIM][Tf2N] ionic liquidpolymeric membranes (ILPMs)[END_REF]. In conclusion, the polymer host matrix was selected based on high mechanical strength, high thermal and chemical stability, and the IL was selected in ILPMs mainly based on its high affinity of target absorbed gases and less viscosity [START_REF] Qiu | Poly(amide-6-b-ethylene oxide)/[Bmim][Tf2N] blend membranes for carbon dioxide separation[END_REF].

Ionic Liquids Composited Mixed Matrix Membranes (ILMMMs)

Mixed matrix membranes (MMMs) are comprised of inorganic fillers and polymers. The separation performances of MMMs depend on the selective sorption/diffusion of the fillers, and the mechanical strength relies on polymer matrices. MMMs combine outstanding gas separation performance of inorganic materials and mechanical strength of polymer membranes.

However, there are still some challenges of MMMs that should be solved. For example, selecting an appropriate filler and polymer [START_REF] Ilyas | Effect of zeolite surface modification with ionic liquid [APTMS][Ac] on gas separation performance of mixed matrix membranes[END_REF], the filler dispersion [START_REF] Huang | Pebax/ionic liquid modified graphene oxide mixed matrix membranes for enhanced CO2 capture[END_REF] and the compatibility of filler and polymer [START_REF] Nuhnen | Role of Filler Porosity and Filler/Polymer Interface Volume in Metal-Organic Framework/Polymer Mixed-Matrix Membranes for Gas Separation[END_REF]. Combining the ILs with inorganic fillers in MMMs (Figure I-7) will enhance the membrane separation performance due to the synergistic effect [START_REF] Nasir | Effect of ionic liquid inclusion and aminofunctionalized SAPO-34 on the performance of mixed matrix membranes for CO2 / CH4 separation[END_REF]. In ILMMMs, ILs are used to increase the absorption capacity and combine with polymer matrixes to improve membranes separation performance further [START_REF] Bhattacharya | Synthesis and characterization of ionic liquid based mixed matrix membrane for acid gas separation[END_REF].

Poly(Ionic Liquid)s Membranes (PILMs)

PILs were synthesized by polymerizable ILs. Usually, to obtain high gas permeably and selective, ILs can be directly imbibed into porous membranes. In this case, ILs can be polymerized to form dense Polymerized Ionic Liquid (PIL) membranes to resolve the mechanical stability issue. Poly(ionic liquid)s (PILs) possess many of the unique combination properties of ILs together with intrinsic polymer properties [START_REF] Eftekhari | Synthesis and properties of polymerized ionic liquids[END_REF][START_REF] Men | Poly(ionic liquid) colloidal particles[END_REF][START_REF] Yuan | Poly(ionic liquid)s: Polymers expanding classical property profiles[END_REF][START_REF] Yuan | Poly(ionic liquid)s: An update[END_REF]. When PILs are used for greenhouse gas separation [START_REF] Yuan | Amine-functionalized poly(ionic liquid) brushes for carbon dioxide adsorption[END_REF][START_REF] Cardiano | Synthesis, CO2 sorption and capacitive properties of novel protic poly(ionic liquid)s[END_REF], they exhibited more excellent sorption capacities and desorption rates than the corresponding ionic monomers [START_REF] Tomé | Pyrrolidinium-based polymeric ionic liquid materials: New perspectives for CO2 separation membranes[END_REF][START_REF] Tomé | Polymeric ionic liquidbased membranes: Influence of polycation variation on gas transport and CO2 selectivity properties[END_REF]. Due to polymer macrostructures, PILMs not only have enhanced processability and durability but also improved mechanical stability. In order to overcome low gas permeability and diffusivity, various strategies have occurred to improve the transport properties of PILMs including loading certain amounts of free room temperature ionic liquids (PIL-IL) [START_REF] Zarca | Synthesis and gas separation properties of poly(ionic liquid)-ionic liquid composite membranes containing a copper salt[END_REF][START_REF] Bara | Effect of Anion on Gas Separation Performance of Polymer-Room-Temperature Ionic Liquid Composite Membranes[END_REF][START_REF] Bara | Synthesis and Performance of Polymerizable Room-Temperature Ionic Liquids as Gas Separation Membranes[END_REF], controlling chain packing by synthesizing PIL copolymer membranes [START_REF] Hemp | Comparing Ammonium and Phosphonium Polymerized Ionic Liquids: Thermal Analysis, Conductivity, and Morphology[END_REF] and incorporating inorganic material [START_REF] Şen | Development of polycarbonate based zeolite 4A filled mixed matrix gas separation membranes[END_REF][START_REF] Shu | A General Strategy for Adhesion Enhancement in Polymeric Composites by Formation of Nanostructured Particle Surfaces[END_REF]. The synthesis of composite membranes by blending PILs with free nonpolymerizable ILs seems to be the most promising strategy to obtain membranes that preserve the mechanical and thermal stability of common polymers which providing high permeation rates and separation factors, which are attractive for industrial purposes. Researchers [START_REF] Bara | Effect of Anion on Gas Separation Performance of Polymer-Room-Temperature Ionic Liquid Composite Membranes[END_REF] prepared composite membranes by polymerization of imidazolium-IL monomers in the presence 20 wt% of free ILs, which results showed that the CO2 permeability increased by approximately 40%. Then, PIL-IL composite membranes draw lots of attention of researchers, and several PIL and IL combinations are studied. Recently, there is reported that supported thinfirm (nanolayers) of PIL-IL composites exhibit excellent CO2 permeation rates together with acceptable CO2 / N2 selectivity, thus indicating that there is still many spaces for improvement in the development of this type of membranes. Phosphonium-based PILs have primarily been synthesized by radical polymerization of IL monomers containing a quaternary phosphonium cation with three attached alkyl chains and a vinyl benzyl polymerizable group along with an associated free cation [START_REF] Cowan | Phosphonium-based poly(Ionic liquid) membranes: The effect of cation alkyl chain length on light gas separation properties and Ionic conductivity[END_REF]. Furthermore, prior works showed that the physical properties of phosphonium-based PILs were influenced by the length of alkyl chain length. Combining PILs with inorganic materials to improve the gas separation and permeability is a promising approach [START_REF] Hudiono | Novel mixed matrix membranes based on polymerizable room-temperature ionic liquids and SAPO-34 particles to improve CO2 separation[END_REF].

Ionic Liquid Gel Membranes (ILGMs)

In contrast to chemical polymerization, ILs can be gelled physically using low organic gelators or polymers as a simpler fabrication alternative. Typically, an IL-gel membrane is prepared by mixing small amounts of a Low-Molecular Weight Organic Gelator (LMOG) with the chosen IL at elevated temperatures [START_REF] Vopička | Ethanol sorption and permeation in fluoropolymer gel membrane containing 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid[END_REF][START_REF] Kusuma | Ionic liquid compatibility in polyethylene oxide/siloxane ion gel membranes[END_REF]. When the samples were cooled down, a physical gel forms due to hydrogen-bonding or/and Van der Waals forces from the gelator and the IL to generate a dilute noncovalent network throughout the sample [START_REF] Mahdavi | Improved CO2/CH4 separation using a nanocomposite ionic liquid gel membrane[END_REF]. The IL-gel membranes suffer from a "flux-mechanical stability trade-off", which means increasing the weight fraction of the gelator that will improve the membrane mechanical stability, however, sacrifice the permeability. LMOG-gelled membranes are difficult to be processed into some shapes like a thin film, which inhibits the applications of the membranes. On the contrary, polymers as gelling agents are more attractive as the gelled membranes are capable of being packed into large modules for easy retrofitting. IL-gel materials are booming because they maintain liquid-like gas transport properties in a solid state, which is much easier to handle and to prepare membrane modules for industrial applications. Although some of the separation performances of ILGMs are promising, the numbers of gelator have limited known to gel RTILs.

Moreover, the thermal stability of the IL-gel membranes is another limitation by the temperature at which the gel reversibly becomes a fluid [START_REF] Yan | Development of a new polymer membrane -PVB/PVDF blended membrane[END_REF][START_REF] Cong | Ionic liquid modified poly(2,6-dimethyl-1,4-phenylene oxide) for CO2 separation[END_REF]. Therefore, new gelators could gel ILs with higher thermal stability and gel functionalization RTILs with enhanced target affinity. This kind of gelator is required the further development of the IL-gel membrane platform.

Ionic Liquid Membrane Contactors (ILMCs)

Membrane contactor (Figure I-8) [START_REF] Ulrich | Membrane-assisted VOC removal from aqueous acrylic latex[END_REF][START_REF] Drobek | PVDF-MFI mixed matrix membranes as VOCs adsorbers[END_REF][START_REF] Feng | Volatile organic compound removal by membrane gas stripping using electro-spun nanofiber membrane[END_REF] is a hybrid process that integrates the advantages of membrane separation and absorption, where liquid absorbents provide the selectivity and the porous/unselective membrane acts as the contacting interface between liquid and gas phase. There are lots of advantages of membrane contactors [START_REF] Zhang | Extraction separation of toluene/cyclohexane with hollow fiber supported ionic liquid membrane[END_REF][START_REF] Banazadeh | A novel process for oxygen absorption from air using hollow fiber gasliquid membrane contactor[END_REF][START_REF] Scholes | Regenerating Membrane Contactors for Solvent Absorption[END_REF][START_REF] Zhao | Status and progress of membrane contactors in post-combustion carbon capture: A state-of-the-art review of new developments[END_REF][START_REF] Darestani | Hollow fibre membrane contactors for ammonia recovery: Current status and future developments[END_REF], such as determined interfacial area, independent control of gas and liquid flow rates and avoidance to drop dragging. For most of the cases, membrane contactor is applied for gas capture at relatively low pressure and temperature [START_REF] Nogalska | Ambient CO2 adsorption via membrane contactors -Value of assimilation from air as nature stomata[END_REF][START_REF] Pang | Effect of non-solvent additive concentration on CO2 absorption performance of polyvinylidenefluoride hollow fiber membrane contactor[END_REF][START_REF] Rostami | Experimental study on the effects of an ionic liquid for CO2 capture using hollow fiber membrane contactors[END_REF]. Various aqueous absorbents have been studied in membrane contactors including aqueous amine solutions [START_REF] Snochowska | Ethanol Recovery from Low-Concentration Aqueous Solutions Using Membrane Contactors with Ionic Liquids[END_REF], amino salt solutions [START_REF] Portugal | Carbon dioxide removal from anaesthetic gas circuits using hollow fiber membrane contactors with amino acid salt solutions[END_REF][START_REF] Rezaei | Prediction of CO2 loading of amines in carbon capture process using membrane contactors: A molecular modeling[END_REF][START_REF] Cabral | Kinetics of the Carbon Dioxide Absorption and Desorption with Amino Acid Salt Solutions using Hollow Fiber Membrane Contactors[END_REF],

enzyme solutions [START_REF] Malankowska | Microfluidic devices as gas -Ionic liquid membrane contactors for CO2 removal from anaesthesia gases[END_REF][START_REF] Yong | The resilience of carbonic anhydrase enzyme for membrane-based carbon capture applications[END_REF] and ammonia solutions [START_REF] Bernal | Valorization of ammonia concentrates from treated urban wastewater using liquid-liquid membrane contactors[END_REF][START_REF] Hasanoğlu | Ammonia removal from wastewater streams through membrane contactors: Experimental and theoretical analysis of operation parameters and configuration[END_REF][START_REF] Liu | Separation of ammonia from radioactive wastewater by hydrophobic membrane contactor[END_REF]. Based on liquid flow direction, there are co-current, cross flow and counter-current configurations of membrane contactors [START_REF] Snochowska | Ethanol Recovery from Low-Concentration Aqueous Solutions Using Membrane Contactors with Ionic Liquids[END_REF]. Based on the structures of membranes, there are flat and hollow fiber membranes.

Moreover, there are polymeric and ceramic membranes according to the materials of membrane used. For the type and geometry, hollow fiber membrane contactors are widely applied due to large mass transfer area [START_REF] Zhang | Wetting mechanism of a PVDF hollow fiber membrane in immersed membrane contactors for CO2 capture in the presence of monoethanolamine[END_REF][START_REF] Tantikhajorngosol | A modeling study of module arrangement and experimental investigation of single stage module for physical absorption of biogas using hollow fiber membrane contactors[END_REF][START_REF] Porcheron | Hollow fiber membrane contactors for CO2 capture: From lab-scale screening to pilot-plant module conception[END_REF]. Hollow fiber membrane contactors (HFMCs) have become attractive for gas separation due to high volume, the high ratio of surface area/volume and toleration of long-term operation. [START_REF] Khulbe | Recent progress in polymeric hollow-fibre membrane preparation and applications[END_REF]. The gas separation performance of HFMCs is mainly affected by pore size and its distribution, selective shin layer thickness, membrane materials and fabrication conditions [START_REF] Khulbe | Recent progress in polymeric hollow-fibre membrane preparation and applications[END_REF][START_REF] Ullah Khan | Status and improvement of dual-layer hollow fiber membranes via coextrusion process for gas separation: A review[END_REF]. Many researchers are attention to improve the gas separation performance of HFMCs [START_REF] Tsai | The preparation of polyelectrolyte/hydrolyzed polyacrylonitrile composite hollow fiber membrane for pervaporation[END_REF][START_REF] Wickramanayake | Investigation of transport and mechanical properties of hollow fiber membranes containing ionic liquids for pre-combustion carbon dioxide capture[END_REF][START_REF] Wickramanayake | Mechanically robust hollow fiber supported ionic liquid membranes for CO2 separation applications[END_REF]. The use of ILs in HFMC processes can bring new opportunities in the use of HFMCs in gas separation. For the type of materials, hydrophobic polymeric membranes are popular due to high porosity and wide availability [START_REF] Sethunga | Optimization of hydrophobic modification parameters of microporous polyvinylidene fluoride hollow-fiber membrane for biogas recovery from anaerobic membrane bioreactor effluent[END_REF][START_REF] Ortiz | Separation of propylene/propane mixtures using Ag+-RTIL solutions. Evaluation and comparison of the performance of gas-liquid contactors[END_REF].

Currently, ILs-based membrane contactor is a new concept that needs to be demonstrated. The excellent thermal stability of the IL component will enable higher temperature applications, and the negligible vapor pressure of the IL will sharply reduce solvent loss and regeneration energy, compared to traditional absorbents.

Discussion

Different kinds of membrane processes relating to the use of ILs for gas or liquid removal are discussed, which showed better performance than conventional processes. Table I-5 shows a comprehensive summary on the advantages and disadvantages of membrane processes containing ILs.

Regardless of the limitation of some ILs, the use of them as absorbents for separation processes have become increasingly important. Although great progress has been done on ILs and membrane separation processes, there are still knowledge gaps that need to be filled.

Additional studies are still needing to i) improve absorption capacity of ILs and membrane separation processes; ii) reduce the toxicity of ILs and overcome the limitations related to the stability, which can broaden the range of applications of ILs; iii) increase the selectivity and stability of ILs and membranes; iv) simplify recycling processes of ILs and adsorbed compounds; v) decrease the cost of absorbent and membrane set-up equipment; vi) solve the difficulty of high boiling gases or liquids desorption.

Because of the above-mentioned issues, our goal is to design a new membrane separation process and thus identify the key parameters enhancing the separation performance. The hybrid membrane combinates ILs and a ceramic membrane used to separate gas or liquid in a continuous green process. This membrane can be regenerated by a simple operation. To "built the ideal membrane process", one has to consider the two main conditions for the good separation performance and regeneration of polluted ILMs. One of them is related to the stability of the supported membrane and implies the use of support with very small pores that ensure that the target gas can pass through pores of support membrane, but ILs cannot. A second condition is the physicochemical properties of the selected IL including the affinity to target gas or liquid and a relatively high viscosity to avoid leakage.

Comparison of present separation processes, this membrane can provide long-time and high temperature operation because of the mechanical and thermal stability of the ceramic membrane. Regeneration of polluted ILM is possible and simple, which just need to use pure and dry airflow at the absorption conditions due to this continuous green process. Without the limitations of the material properties (e.g. plasticization and Robeson upper bound line of polymers, limit the selection of gelators, poor compatibility of filters and polymers), the ILMs could maximize the absorption properties of ILs. Moreover, this ILM also provides new thinking that using an inorganic porous membrane as interface materials in ILMCs, which could overcome existing disadvantages of ILMCs such as poor stability and dissolving the polymeric or polymer-based sealing membrane into ILs.

ILGMs

-Liquid-like gas transport properties in a solid state, which is easier to handle and to prepare membrane modules for industrial applications -Gas permeability is increased -Thermal and mechanical stability are limited -Gas permeability and ideal selectivity are low -Gelators are limited -High packing density is required -Suffering the trade-off effect between signal gas permeability and selectivity of gas pair

ILMCs

-Long-time operation -Higher active surface area to volume ratio -Allow the solvent phase to be continuously renewed -The low resistance of gas flow -Self-supporting structure -Ability to perform at high pressure -Determined interfacial area -Independent control of gas and liquid flow rates -Avoidance the drop dragging -Reduce the solvent loss and regeneration energy -Poor stability and processability -Selection of materials is limited -Some ILs can dissolve the polymeric or polymer-based sealing membrane -The low surface tension of ILs

Chapter II. Materials and Methods

Ionic Liquid Membrane (ILM)

Preparation of an ILM

As shown in Figure Ⅱ-1, the support of ILMs is a multichannel tubular ceramic membrane (Alsys Society, Salindres, France). For the first experiment, the ceramic multichannel membrane was divided into 4 parts of 25 cm, and each of them was sealed with the solution normally used to seal the inlet/outlet the ceramic membrane. The coating is a fluoropolymer that is conventionally used for the ends of micro-ultra-nanofiltration membranes. The molecular weight cut off (MWCO) is very low and function of the IL used. The higher viscosity of the IL, the higher the MWCO is. But in all the cases, in this study, a MWCO of 1 kDa ceramic membrane was used (1 Da = 1 g L -1 ). Some channels of the ceramic membrane are filled with ILs, and some channels are empty as gas or liquid access. The methodology describes is optimized after different tests. The channels containing ILs are closed by glue on each extremity to keep the ILs inside. Before preparing the ILM, the dissolved gases into the selected IL are removed by evaporating and heating. For ILM fabrication, first, the channels containing the IL are closed by glue on one extremity, while other channels are closed by rubber plugs on another extremity. Then the IL is filled into the blocked channels until full. The channels filled with the IL are closed on another extremity by glue. The glue is a mixture of alkylamine (R-NH2) and ethylene oxide derivatives (R 1 -CH-O-CH-R 2 ) that was purchased from Sika (Paris, France). It is not dissolved by the selected IL. The specific stainless-steel carter is used to stabilize and connect the ILM. The sealing between inlet/outlet and permeate is ensured by a thoric seal at the inlet and outlet. Full details are given in Table Ⅱ-1. The porous hydrophobic ceramic membrane acts as a fixed interface between the gas or liquid phase and the IL phase without dispersing one phase into another. The membrane offers a flexible modular energy-efficient device with high specific surface area. The absorption process can offer a very high selectivity and a remarkably driving force for mass transfer even at very low concentration.

Channels diameter (mm) 2

Total number of channels 52

Number of channels with IL 32

Surface area (m 2 ) 4.0 × 10 -2

Porosity (%) 35 -37

Molecular weight cut-off (Da) 1000

Innovations and Applications of ILM

The main inventions of this ILM include following points: i) the ILM combines the advantages of membranes (modularity and compactness) with the absorption of ILs (high absorption capacity and selectivity); ii) this ILM can achieve separation and regeneration processes in the single and same unit; iii) this ILM can tolerate long-time operation; iv) membrane can separate the suspended matters or pollutants from liquid or gas mixture and protect the IL; iv) this ILM can be used as a contactor; v) when ILM contains many kinds of ILs in different channels, it can separate several pollutants simultaneously; vi) ILMs can be series, parallel and combination connected based on concentration and flow rate of pollutants stream; viii) this ILM can work at high temperature in agreement with the viscosity of the IL used. Moreover, modules of membranes and membranes into the module can be changed according to the separation tasks, for example, prolong the membrane and increase the numbers of channels.

The research approach proposed in this study is summarized as follows: i) realization of the ILM; ii) selection of the IL according to the physicochemical properties expected to enhance the strong absorption of pollutant and stability with process conditions; iii) optimization of parameters including system pressure, temperature, the concentration of pollutant inlet and flow rate; v) identification of the factors influencing suspended matters or pollutants uptake; v) regeneration of pollutant loaded ILM; vi) proposal of the mechanisms of absorption and simulation of the separation process.

Test Bench

Global Description

The test bench (Figure Ⅱ-2) that was developed for this study consists of three parts, including a gas and humidity generation system, a thermostatically controlled chamber for regulating the temperature during the various trapping processes and a data acquisition system. The concentration of the gas mixture that will go to the membrane process can be calculated by the following equation:

𝐶 𝑔𝑎𝑠 𝑝𝑟𝑜𝑐𝑒𝑠𝑠 = 𝐶 𝑔𝑎𝑠 𝑏𝑜𝑡𝑡𝑙𝑒 × 𝑄 𝑀𝐶𝐹2 𝑄 𝑀𝐶𝐹1 +𝑄 𝑀𝐶𝐹2 (II-1)
where Cgas process is the concentration of gas will go to membrane process (ppm); Cgas bottle is the concentration of gas in the gas bottle (ppm); QMCF1 and QMCF2 are the volume flow rates of pure air and gas respectively (mL min -1 ).

If a humid gas mixture is needed, humidity is generated from pressurized liquid water. The water vapor is injected into the diluted gas by a proportional valve, which keeps the hygrometry of the mixture constant. The vapor pressure is kept sufficiently by heating and regulating the temperature of the vaporization chamber (Figure Ⅱ-3). In order to verify generated humidity values, a second humidity sensor is placed at the output of the reactor.

The thermostatically controlled chamber: It keeps the temperature of the pilot constant during all the trapping processes. Inside the thermostatically controlled chamber, installed the carter contained membrane and connect to process, a flow meter to monitor the flow through all the line of the process, a digital pressure regulator, a humidity sensor and VOC sensor. With the sizeable industrial membrane (length = 1.178 m), it could not register into this thermostatically controlled chamber due to the space limitation. In this specific case, the industrial membrane experiment was conducted at room temperature.

The data acquisition system: it connects to a computer for data collection from the sensors continuously over time.

After the description of the test bench generally, there are also some detailed modifications depending on applications. In this study, the main applications of ILMs can be achieved by this test bench, such as i) humidity removal; ii) VOCs removal.

Humidity Removal Process

As shown in Figure II-4, the process of humidity removal, the different levels relative humidity generation can be completed by gas and humidity generation system. In the thermostatically controlled chamber, a carter is used to stabile membranes and connected to other parts. After the membrane are following a relative humidity sensor (RH sensor), a pressure regulator and a flowmeter. The data acquisition system is connected to the RH sensor.

VOCs Removal Process

Before testing the separation performances of ILMs, it is necessary to check each part of the process to exclude their influences on VOCs removal and to ensure that only selected IL can absorb VOCs. As shown in the following, the carter and the tubular ceramic membrane (the support membrane) were tested on different operating conditions.

For this section, experimental set-up and process improvement are mainly carried out in a thermostatically controlled chamber. The carter can stabilize and connect membranes. The PID sensor monitors the concentration of toluene out of the carter. The pressure regulator is used to control and monitor the pressure of process. All the blank experiments were registered at 70 ppm of toluene inlet with 0.3 L min -1 and 20 ℃ unless otherwise specified. In our experimental conditions, a binary gas mixture of air and toluene was used. Considering the low solubility of air in the selected ILs, and a very low interaction between air and toluene, therefore, the effects of air in the toluene absorption by the ILM was neglected.

The only carter connects to process to check the sensor response (Figure Ⅱ-5(a)).

The pressure regulator was set as 1.00 atm. The result (Table Ⅱ-2) shows sensor worked well with 2 minutes gas flow. However, the flow rate and pressure could not stable. When the gas flow passes from the tube to the carter, the diameter of the gas pipeline increases sharply. And then, from the carter to the tube, the diameter of the gas pipeline decreases rapidly. Therefore, the changes in the diameter of the gas pipeline cause the velocity of gas change resulting in pressure changing. After checking all the devices were connected well, a pressure regulator was placed after the PID sensor and slightly increased system pressure from 1.00 atm to 1.07 atm. Therefore, the difference in the pressure between gas inlet and outlet was reduced or eliminated to obtain a stable flow rate. For all the experiments following, the pressure was set at 1.07 atm. The final process was proposed after checking each device and operating parameters.

Carter contained a ceramic membrane (without ILs) connects to process, as shown in

Experiments show that all devices and normal operating parameters would not influence on PID sensor response. All results of this part are detailed in Appendix 2. For VOCs absorption process (Figure II-8), different concentrations of a target gas with a certain flow rate was generated by the gas generation system. In the thermostatically controlled chamber, there are two ways for a gas mixture. First, the mixed gas to go VOCs sensor to calibrate and check gas sensor response normally. Second, the mixed gas passes through the ILM and then go to VOCs gas sensor to investigate membrane performance. Desorption of toluene from the saturated ILM is a critical issue considering potential applications. The desorption experiments were carried out at the same process with absorption. The only difference between absorption and desorption was feed stream. Desorption experiments carried out with continuous dry air with absorption operating conditions. Desorption of toluene was complete in all the cases, that is, all the toluene absorbed was desorbed at the absorption temperature without heating or vacuum.

Sensors

Humidity Sensor

The relative humidity (RH) sensor (Figure II-9) is a laser trimmed, thermoset polymer capacitive sensing element with on-chip integrated signal conditioning, which was purchased from Honeywell (HIH-4000-004). Accuracy of RH sensor is ± 3.5%. The response is from 0 to 100% RH. The values of RH are calculated from the sensor response by the following equation:

𝑅𝐻 (%) = 𝑠𝑒𝑛𝑠𝑜𝑟 𝑟𝑒𝑠𝑝𝑜𝑛𝑠𝑒 5 ⁄ -0.16 0.0062×(1.0546-0.00216×𝑇) (II-2)
where RH is the value of relative humidity (%); T is working temperature (℃); sensor response (V).

VOCs Sensor

The VOCs sensor is a photoionization detector (PID sensor) (Figure II -10).

Photoionization Detectors (PIDs) are the easiest and most efficient way to detect VOC levels.

Although not as selective without the use of a gas chromatography column, a stand PID provides real-time measurement of many VOCs in a portable format or fixed format. These detectors enable the user to react swiftly to any potential threat, without waiting for the evaluation of a time-weighted average (TWA). Sensitivity can be increased by the selection of ultraviolet (UV) lamp, as well as detector range. The sample gas is exposed to a UV light from a lamp which ionizes the target gases to be detected by the instrument and reported as a concentration. VOC's with an ionization potential (IP) less than the eV of the lamp will be detected by photoionization. The most common lamp is the 10.6 eV, although a 10.0 eV can also be used for increased selectivity. In this study, a piD-POD® from AMETEK MOCON was used. Since a photoionization detector (PID) does not destroy the sample, the piD-POD is a direct way to provide a total volatile organic compounds (TVOCs) measurement. The piD-POD has no moving parts and consists of a cylindrical housing which accommodates the piD-TECH® eVx photoionization sensor and inlet/outlet sample ports. It is engineered for inlet flows of up to 0.3 L min -1 and equipped with a PCBmounted connector with a mating adapter.

Calibration of the PID sensor for toluene:

The VOCs sensor was exposed to a certain concentration of toluene for 2 to 5 minutes with 20 ℃, gas flow rate 0.3 L min -1 and 1.00 atm.

Accuracy of VOCs sensor is ± 10%. The response is from 0 to 90 ppm of toluene. The concentration of gas is calculated from the sensor response by the following equation:

𝐶 𝑔𝑎𝑠 = 28.579 × 𝑉 𝑠𝑒𝑛𝑠𝑜𝑟 𝑟𝑒𝑠𝑝𝑜𝑛𝑠𝑒 -1.228 (II-3)
where Cgas is the concentration of gas (ppm); Vsensor response is sensor response (V).

Operating Conditions

Several studies have been investigated in the fabrication and characterization of support membranes. Moreover, the effects of different absorbents and membrane materials are documented well. However, the research of the effects of operating conditions on the performance of membranes for gas absorption is still rare. In this work, an ILM was used to study the effects of the operating parameters including different ILs, flow rate inlet, pressure, the concentration of gas inlet and temperature on the physical absorption. In addition, a longterm absorption process and regeneration of polluted ILM at optimized conditions were studied.

The choice of the testing pressure range is explained by the pressure at the gas effluent as a function of the IL surface tension, and high pressure can move the IL outside of the channel.

However, it is important to note that the MWCO is small, and the pore diameter is lower than 2.0 nm to reduce this risk. The critical entry pressure of the membrane can be calculated by the Young-Laplace equation [START_REF] Dai | Membrane absorption using ionic liquid for pre-combustion CO2 capture at elevated pressure and temperature[END_REF]. The pressure to push the IL into the small pore is higher than 55.0 atm. The pressure ranges were lower than 55.0 atm (both humidity and VOCs removal)

for the ILM to investigate the effect of the driving force resulting into target gas through the channel walls and reaching to IL channels.

ILs for VOCs (Toluene) Removal

In this section, our aim is to select an IL with high capacities and adequate properties for

Analysis of Experimental Data

In our system, all the inlet parameters were constant including flow rate, inlet concentration of gas (humidity and toluene), pressure and temperature. The concentration of gas outlet the ILM was obtained by a sensor. When the concentration of gas inlet and outlet of the ILM was equal, it means that the ILM has reached its saturation. The mass of gas absorbed by ILM can be calculated by the following equations:

𝑚 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 = ∫ 𝑄 𝑔 (𝐶 𝑖𝑛 -𝐶 𝑜𝑢𝑡 )𝑑𝑡 𝑡 0 ( 1
)
where Qg is the flow rate (L min -1 ), mabsorbed is the amount of absorbed by ILM (mg), Cin and Cout are the inlet and outlet concentration of toluene in the gas flow (mg L -1 ), t is the time (sec or min).

In order to compare the performance of the ILM for gas absorption, the variation of outlet concentration versus time was studied, and the mass of gas absorbed by ILM can be calculated.

Introduction

Humidity has negative effects on various applications. The separation of humidity from a gas mixture is required in numerous industrial processes. It is interesting to study the influence of water vapors on the performance of materials or processes for gas removal because water vapor always exits in the atmosphere and industry processes. For example, water vapors take competitive adsorption between target gas and water molecules [START_REF] Park | Influence of humidity on the removal of volatile organic compounds using solid surfaces[END_REF][START_REF] Liu | Enhanced adsorption of benzene vapor on granular activated carbon under humid conditions due to shifts in hydrophobicity and total micropore volume[END_REF].

For the industrial gas processes, as the temperature and pressure change during the production of the gas, water can condense from the gas stream, which results in the blockage of gas transmission lines [START_REF] Eslamimanesh | Application of gas hydrate formation in separation processes: A review of experimental studies[END_REF]. In this case, it is necessary to separate the moisture from the feed streams.

Metal oxide gas sensors are widely used to monitor the concentrations of harmful gases due to their high sensitivity. However, the sensitivity of metal oxide sensors can be decreased by 50% in the presence of humidity [215,[START_REF] Favard | Ionic Liquids Filter for Humidity Effect Reduction on Metal Oxide Gas Sensor Response[END_REF].

Recently, IL-based humidity removal processes have attracted more attention. Water vapors absorption from air is much higher for more hydrophilic ILs. The research has reported that the imidazolium-based ILs are more hygroscopic than others [START_REF] Cuadrado-Prado | Experimental measurement of the hygroscopic grade on eight imidazolium based ionic liquids[END_REF]. For the application of ILs in separation processes, there are mainly focus on two parts of view. First, IL acts as an absorbent in a contactor [START_REF] Luo | Dehumidification performance of [EMIM]BF4[END_REF]. Second, IL acts as a part of membrane materials in the porous of porous support [START_REF] Zhao | Effect of water in ionic liquid on the separation performance of supported ionic liquid membrane for CO2/N2[END_REF]. However, the efficiency of these ILs processes has not been investigated widely for humidity separation from the gas mixture. According to the previous study, there are several ILs which have high absorption capacities for humidity. Those hygroscopic ILs are a good choice for water vapors uptake. Combination of advantages of a ceramic membrane and unique properties of ILs has brought new opportunities in applications of IL-based membrane processes. In this chapter, the ILMs are used to remove humidity and are believed to be more environmentally friendly and energy-saving compared to other commercial separation processes.

This work presents the application of the hygroscopic ionic liquid 1-butyl-3methylimidazolium bromide ([Bmim]Br) in humidity removal processes. Furthermore, the optimal operating conditions in a green continuous separation process are investigated. It is expected that the stability and separation ability of the ILM for humidity removal will be enhanced due to the strong absorption of the selected IL. The regeneration process of water loaded ILM is efficient and straightforward, and the ILM showed high stability during longtime operation.

IL-based Filter Capturing Humidity to Protect Gas Sensors

The concentration of RH in the atmosphere ranges from 30 to 90% (1.0 atm, 25 ℃). The presence of humidity often limits the performances of metal oxide gas sensors, particularly in terms of sensitivity. Almost all types of metal oxide gas sensors have a tendency to adsorb humidity to their sensitive surface resulting in the degradation of detection performances [215,[START_REF] Favard | Ionic Liquids Filter for Humidity Effect Reduction on Metal Oxide Gas Sensor Response[END_REF]. It is necessary to eliminate or reduce the dependence of metal-semiconductor gas sensors response on humidity. IL-based filters placed upstream of sensors to capture water molecules is a promising method.

IL-based Filter

The

IL-based Filter Capturing Humidity

In order to study the humidity influence on the sensor responses, the metal oxide gas sensor was exposed to 500 ppb of VOCs mixture (Benzene, Toluene, Ethylbenzene and Xylene) for 4 minutes with and without humidity (RH = 0 / 50%). As Because our membrane is a hydrophobic ceramic membrane, the water absorption is only dependent on its affinity with water of the groups compounding the ILs. Normally, water can interact with both the cations and anions. Therefore, the chemical structure of the ILs would affect water absorption [START_REF] Kamimura | Solubility-switchable Ionic Liquids: A Control of Hydrophilicity and Hydrophobicity Using a Protective Group[END_REF][START_REF] Restolho | Moisture Absorption in Ionic Liquid Films[END_REF][START_REF] Zhou | An Overview of Mutual Solubility of Ionic Liquids and Water Predicted by COSMO-RS[END_REF][START_REF] Freire | An overview of the mutual solubilities of water-imidazolium-based ionic liquids systems[END_REF]. The Br -anion is a characteristic group of

[Bmim]Br that interacts with water molecules [START_REF] Kudasheva | Dehumidification of air using liquid membranes with ionic liquids[END_REF][START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF][START_REF] Francesco | Water sorption by anhydrous ionic liquids[END_REF]. In the presence of water, the hydrogen bond involving the Br -was enhanced. In addition, the anions preferentially interact with water, and since the anion promotes water molecule association through hydrogen bonds, the [Bmim]Br was mainly responsible for water absorption [START_REF] Zhang | The Hydrogen Bonding Interactions between the Ionic Liquid 1-Ethyl-3-Methylimidazolium Ethyl Sulfate and Water[END_REF][START_REF] Khalifa | Surface enhancement of water at the ionic liquid-gas interface of [HMIM][Cl] under ambient water vapor[END_REF][START_REF] Lovelock | Influence of the ionic liquid/gas surface on ionic liquid chemistry[END_REF].

For the [Bmim][PF6],
according to the research of Cammarata et al. [START_REF] Cammarata | Molecular states of water in room temperature ionic liquids[END_REF], water molecules dissolved in the anions are not self-aggregated water molecules interacting via hydrogen bonds with the anions in a symmetric complex (anion--H-O-H--anion). This means that water molecules do not interact with themselves, resulting in lower sorption than [Bmim]Br. There are longer alkyl chains in the cation of [3htdp]Cl, which could decrease the water solubility [START_REF] Khalifa | Surface enhancement of water at the ionic liquid-gas interface of [HMIM][Cl] under ambient water vapor[END_REF] leading to a slower sorption rate in the future [START_REF] Broderick | Water at the Ionic Liquid-Gas Interface Examined by Ambient Pressure X-ray Photoelectron Spectroscopy[END_REF][START_REF] Cao | Water Sorption in Functionalized Ionic Liquids: Kinetics and Intermolecular Interactions[END_REF][START_REF] Torrecilla | Effect of Relative Humidity of Air on Density, Apparent Molar Volume, Viscosity, Surface Tension, and Water Content of 1-Ethyl-3methylimidazolium Ethylsulfate Ionic Liquid[END_REF]. The impact of the anion types on the water absorption ability by ILs was found to be even stronger when compared to that of the cation types. Thus,

Optimizing Operating Parameters for Humidity Removal by ILM

In this part, the IL was used as a physical absorbent to separate water vapor from air. The ceramic tubular membrane acts as hydrophobic support. Also, the effects of various parameters were tested, and the results were discussed.

Flow Rates

Flow rate is one of the key operating factors affecting the performance of membrane processes. The tests were carried out from 0.50 to 1.50 L min -1 of feed flow rates, and the other operating parameters were constant.

Pressure and Relative Humidity

In order to investigate the effect of differential pressures on humidity transport in the porous support, the ILM was registered at different pressures from 1.00 to 1.20 atm. One of the advantage of vapor separation is that a much higher pressure can be applied across the membrane, which should translate into a higher driving force [START_REF] Zhao | Vapor pressure measurement for binary and ternary systems containing a phosphoric ionic liquid[END_REF][START_REF] Wang | Vapor pressure measurement for water, methanol, ethanol, and their binary mixtures in the presence of an ionic liquid 1-ethyl-3methylimidazolium dimethylphosphate[END_REF][START_REF] Park | Effect of operating parameters on dynamic response of water-to-gas membrane humidifier for proton exchange membrane fuel cell vehicle[END_REF]. When the feed flow rate and concentration of humidity inlet are constant, from The water vapor concentration inlet is another variable that can affect the membrane's separation performance. In this case, when the inlet flow rate was constant, the higher feed concentration provided a higher driving force. This effect is shown in

Temperature

Separation temperature is an important parameter for vapor separation. A higher temperature means a higher saturated vapor pressure for a certain feed, which means a higher driving force and flux. The diffusivity of gas molecules increases exponentially with temperature, and a higher flux is expected at higher separation temperature [START_REF] Finotello | Room-Temperature Ionic Liquids: Temperature Dependence of Gas Solubility Selectivity[END_REF][START_REF] Hayduk | Temperature coefficient of gas solubility for regular solutions[END_REF]. As shown in Figure Ⅲ-5(a), when the operating temperature increases in the porous media, the thermal motion of water vapor molecules increases and the transfer resistance of supported ceramic membrane decreases [START_REF] Park | Effect of operating parameters on dynamic response of water-to-gas membrane humidifier for proton exchange membrane fuel cell vehicle[END_REF], which results in a stronger diffusion. With the temperature increasing, the flux of water vapor in a gas channel increases, because the saturation pressure of the gas increases dramatically at the higher temperature. Therefore, the vapor mass transfer from a gas channel to the ionic liquid channel increases due to the increased activity difference between the two channels. of water absorbed by the IL was higher when the ILM was registered at a lower temperature than at a higher temperature. The variation of the solubility versus temperature is a function of the solubility [START_REF] Finotello | Room-Temperature Ionic Liquids: Temperature Dependence of Gas Solubility Selectivity[END_REF][START_REF] Hayduk | Temperature coefficient of gas solubility for regular solutions[END_REF][START_REF] Swarnkar | Performance of a vapour absorption refrigeration system operating with ionic liquid-ammonia combination with water as cosolvent[END_REF]. For low-solubility gases, the solubility will increase with increasing temperature, but for larger-solubility gases, the solubility will decrease with increasing temperature. For the IL used in this study, the maximum mass of 1.42 gram of water was absorbed by 10 gram of [Bmim]Br, so the water vapor appears to be larger-solubility (1 gram of solute dissolve into 10 gram of solvent).

If we supposed that there was no phase transformation in the water vapor absorption by the ionic liquid, the water always remains in the gas phase. When increasing temperature, the dissolved water will leave an ionic liquid (in the liquid phase). This can explain why we have a good regeneration of our membrane by increasing the temperature (section 5). It also means that the mass of water absorbed decreases with increasing temperature and a flow of dry air.

The Position of Gas Channels

The position of the gas channels can also affect the separation performance of ILM. As remove humidity from a feed stream faster and more effectively. However, when these two membranes reached their absorption saturation, the total mass of water absorbed was almost equal (2.9 ± 0.5 g) (Table Ⅲ-1). Results showed that the position of the gas channels only affects the absorption rate there is no effect on the final removal mass. On average, for Membrane (a), of the outermost IL channels, only half can be regarded as active (bule arrow -"non-active part"), and the other half is not working at the beginning of absorption.

Oppositely, for Membrane (b), all the IL channels can be regarded as active.

Regeneration of the Water-loading ILM

Processes for the regeneration of rich water loaded ILMs were operated in the same unit with the same conditions, but only the feed stream was changed, from contained humidity to dry air. The flow rate was constant at 0.50 L min -1 , with 1.00 atm and 32 ℃. When carried on the desorption process, the concentration of the feed just changed from 35% to 0of RH ( which results in a weakened mass transfer. The feed concentration only affected the absorption rate, but not the total mass. When the temperature of the operating system increases, the efficiency of the membrane on humidity removal decreased. However, the processes were operated at room temperature. The regeneration process is simplified and available and just needs to change the feed stream from contained humidity to dry air. After absorption and desorption cycles, the absorbing capacity of ILM was not decreased. Moreover, there was no heavy loss of IL observed during experiments realized with the same membrane. IL-based membrane processes will be the dominating green processes for humidity separation.

Introduction

Volatile organic compounds (VOCs), as a class of organic substances, are involved in several environmental pollutions and health damages. For example, the emission of VOCs in the atmosphere causes environmental problems such as greenhouse effect, photochemical smog, and ozone depletion. For human health, VOCs are absorbed by the respiratory system, causing brain and liver damages [START_REF] Soni | Effects of VOCs on Human Health[END_REF][START_REF] Lyu | Elucidating emissions control strategies for ozone to protect human health and public welfare within the continental United States[END_REF][START_REF] Li | A comprehensive classification method for VOC emission sources to tackle air pollution based on VOC species reactivity and emission amounts[END_REF]. It is necessary to reduce the emission of VOCs into the atmosphere. The current processes of VOCs abatement include destructive and recovery processes. Besides, recovery processes show more environmental-friendly. VOCs emissions control can be carried out in recovery processes such as adsorption on porous materials [START_REF] Zhu | A critical review on VOCs adsorption by different porous materials: Species, mechanisms and modification methods[END_REF][START_REF] Liu | A new insight into adsorption state and mechanism of adsorbates in porous materials[END_REF], membrane separation [START_REF] Belaissaoui | Energy efficiency of a hybrid membrane/condensation process for VOC (Volatile Organic Compounds) recovery from air: A generic approach[END_REF][START_REF] Ahmad | Interfacial sealing and functionalization of polysulfone/SAPO-34 mixed matrix membrane using acetate-based ionic liquid in post-impregnation for CO2 capture[END_REF][START_REF] Yan | Ionic liquids combined with membrane separation processes: A review[END_REF], condensation [START_REF] Li | Design and dynamic behaviour investigation of a novel VOC recovery system based on a deep condensation process[END_REF][START_REF] Ayrilmis | Effect of Wood-drying Condensate on Emission of Volatile Organic Compounds and Bonding Properties of Fibreboard[END_REF], and absorption by conventional solvents [START_REF] Uragami | Permeation and separation characteristics in removal of dilute volatile organic compounds from aqueous solutions through copolymer membranes consisted of poly(styrene) and poly(dimethylsiloxane) containing a hydrophobic ionic liquid by pervaporation[END_REF][START_REF] Ortiz-Martínez | Chapter 4 -Separation of volatile organic compounds by using immobilized ionic liquids[END_REF]. Selection of an efficient VOCs treatment process depends on the concentration and flow rate of pollutants, the natural compounds, and other factors. As mentioned in Chapter I, adsorption and absorption processes can treat much higher ranges of concentration and flow rate of pollutants than others. Design and synthesis of porous materials for adsorption of VOCs such as metal organic frameworks [START_REF] Wang | Remarkable adsorption performance of MOF-199 derived porous carbons for benzene vapor[END_REF][START_REF] Xu | A copper based metal-organic framework: Synthesis, modification and VOCs adsorption[END_REF][START_REF] Shafiei | Synthesis and adsorption performance of a modified micro-mesoporous MIL-101(Cr) for VOCs removal at ambient conditions[END_REF], porous polymers [START_REF] Qi | Synthesis of porous carbon beads with controllable pore structure for volatile organic compounds removal[END_REF][START_REF] Satilmis | Electrospinning of Ultrafine Poly(1-trimethylsilyl-1-propyne) [PTMSP] Fibers: Highly Porous Fibrous Membranes for Volatile Organic Compound Removal[END_REF][START_REF] Liu | Porous polymeric resin for adsorbing low concentration of VOCs: Unveiling adsorption mechanism and effect of VOCs' molecular properties[END_REF], zeolites [START_REF] Ikhlaq | Catalytic ozonation of chlorinated VOCs on ZSM-5 zeolites and alumina: Formation of chlorides[END_REF][START_REF] Megías-Sayago | Volatile organic compounds (VOCs) removal capacity of ZSM-5 zeolite adsorbents for near real-time BTEX detection[END_REF][START_REF] Wołowiec | Experimental Study on the Removal of VOCs and PAHs by Zeolites and Surfactant-Modified Zeolites[END_REF], and active carbon [START_REF] Hariz | Absorption of toluene by vegetable oil-water emulsion in scrubbing tower: Experiments and modeling[END_REF][START_REF] Long | VOCs reduction and inhibition mechanisms of using active carbon filler in bituminous materials[END_REF][START_REF] Hunter-Sellars | Adsorption of volatile organic compounds by industrial porous materials: Impact of relative humidity[END_REF][START_REF] Ma | Adsorption of volatile organic compounds on modified spherical activated carbon in a new cyclonic fluidized bed[END_REF], has been extensively studied.

However, this process may be limited when the gas flow with humidity. The presence of humidity has a noticeable impact on the adsorption of gases and volatiles [START_REF] Park | Influence of humidity on the removal of volatile organic compounds using solid surfaces[END_REF][START_REF] Zhou | Combined effects of temperature and humidity on indoor VOCs pollution: Intercity comparison[END_REF][START_REF] Xu | An experimental study of relative humidity effect on VOCs' effective diffusion coefficient and partition coefficient in a porous medium[END_REF]. In addition, because the moisture in the gas could block adsorption sites, it could be a result difficult to reuse the adsorbent [START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF].

The absorption process is the most efficient and straightforward for VOCs removal. In the absorption process, selecting an appropriate liquid absorbent is the key factor to achieve an effective and green separation process. Traditional organic solvents show the disadvantages of their not negligible volatility. A new solution, the addition of a nonaqueous solvent, has been found to enhance affinity for the solutes [START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF][START_REF] Tandjaoui | A combination of absorption and enzymatic biodegradation: phenol elimination from aqueous and organic phase[END_REF]. For example, silicone oils, solid polymers, and n-alkanes are widely used. Recently, ILs have attracted attentions widely as potential solvents to replace volatile organic solvents. The most important feature of ILs is the fact that they can dissolve both organic and inorganic compounds. Broad selecting discretion of their properties allows designation of a liquid solvent which dissolves well compounds from the solvent [START_REF] Kudłak | Selected issues related to the toxicity of ionic liquids and deep eutectic solvents-a review[END_REF]. In addition, the type of anion, as a key factor, influences the gas solubility on ILs.

The length of the alkyl chain of the cation is also significant. The high affinity of imidazoliumbased ILs for VOCs have been confirmed.

In this study, [Bmim][PF6] and [Bmim][NTf2] were used as liquid absorbents solution and were combined with ceramic membranes for the treatment of VOCs. The porous ceramic membrane acts as a contacting device between the gas and liquid phase. The separation of the target gas relied on the solubility of the gas in the IL. Among VOCs, toluene is one of the most widely used gases in the industry [START_REF] Cheng | Hierarchical porous carbon fabricated from cellulose-degrading fungus modified rice husks: Ultrahigh surface area and impressive improvement in toluene adsorption[END_REF][START_REF] Gregis | Characterization of materials toward toluene traces detection for air quality monitoring and lung cancer diagnosis[END_REF]. Therefore, toluene, as a typical aromatic hydrocarbon, was captured as a model of VOCs.

The carter and the support membrane have no influence on the concentration of toluene, which has been demonstrated in Chapter II. The PID sensor calibration was validated. The PID sensor responses are not influenced by the flow rate, system pressure and temperature in our test ranges. Toluene is absorbed by the ILM because of the affinity of toluene and selected IL.

Selection of ILs for Toluene Absorption

The physicochemical properties of ILs like density and viscosity play important roles in the performance of the gas absorption process. Several publications have demonstrated that imidazolium-based ILs have high affinity and capacities for absorbing toluene [START_REF] Wang | Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal[END_REF][START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF][START_REF] Tan | The effect of imidazolium and phosphonium ionic liquids on toluene absorption studied by a molecular simulation[END_REF].

Moreover, the partition coefficients in [Bmim][PF6] and [Bmim]

[NTf2] show comparable or higher than those of typical organic solvents [START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF]. Therefore, these two ILs were selected as due to higher affinity for toluene. This phenomenon was already confirmed by other researchers [START_REF] Wang | Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal[END_REF][START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF]. The toluene absorption capacity on ILs is influenced by both cation structure and anion nature. For cation structure, imidazolium, tetra-substituted phosphonium and ammonium cations show good absorption capacity for toluene. Nevertheless, the viscosity of ILs with tetrasubstituted phosphonium and ammonium cations are higher than imidazolium-based ILs [START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF][START_REF] Gardas | Densities and Derived Thermodynamic Properties of Imidazolium-, Pyridinium-, Pyrrolidinium-, and Piperidinium-Based Ionic Liquids[END_REF][START_REF] Khupse | Dramatic Change in Viscosities of Pure Ionic Liquids upon Addition of Molecular Solvents[END_REF][START_REF]Liquids intermediate between "molecular" and "ionic" liquids: Liquid Ion Pairs? -Chemical Communications[END_REF]. For anion nature, highly halogenated hydrophobic anions can enhance the toluene absorbing [NTf2 -] anion seems to have the best affinities for toluene [START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF][START_REF] Quijano | Potential of ionic liquids for VOC absorption and biodegradation in multiphase systems[END_REF]. Therefore,

[Bmim][NTf2] has been selected as an absorbent for toluene absorption.

Table IV-

Effects of Operating Parameters on Toluene Absorptivity by the ILM

The absorption performance of toluene by the ILM was investigated by studying the influences of variable operating parameters including the concentration of toluene inlet, flow rate, system pressure and temperature. When the concentration of toluene outlet of the ILM equaled to inlet, the ILM was considered to reach its absorption saturation. reach saturation. In gas-liquid absorption process, a toluene film (gas phase) and an IL film (liquid phase) were formed on the interface based on two-film theory [START_REF] Ma | Concentration control of volatile organic compounds by ionic liquid absorption and desorption[END_REF]. Toluene must pass through these films to be dissolved into the IL. The concentration gradient of the interface was increased with toluene concentration increasing due to higher concentration providing a higher driving force. This effect was favorable for the toluene absorption in an ILM. Normally, higher toluene concentration in the gas phase was high results a higher concentration in liquid phase own to vapor-liquid equilibrium. There are two other assumptions that can cause this result. i) not all IL worked during this process. Furthermore, the IL in the center of channels might not absorb toluene because IL was stationary in the channels. ii) the ILM under 50 ppm of toluene still absorbing toluene at experiment stop time, but the absorption rate was very slow, which could not be exhibited clearly on the figure. In conclusion, the absorption performance of ILM under 70 ppm of toluene was better. Therefore, 70 ppm of toluene inlet was selected for the following experiments.

The Concentration of Toluene Inlet

Flow Rate

The effect of different flow rates between 0.10, 0. As Figure IV-3(c) shown, it was confirmed that the toluene absorption rate was increased with flow rate increasing from 0.10 to 0.30 L min -1 . However, when the flow rate increased from 0.10 to 0.15 L min -1 , there was no significant difference of absorption rates. This result indicated that for this ILM, the influences of flow rate should be in a certain range, and if the flow rate too small, the quantity of toluene inlet was limited, resulting in absorption rate reducing.

Pressure

Pressure for the gas phase is an important factor for ILM due to the gas-liquid absorption mechanism. Experiments were performed for effects of pressure on ILM in the operating conditions of 20 ℃, gas flow rate = 0.30 L min -1 , pressure range from 1.07 to 1.17 atm. The experiment data were shown in Figure IV-4. Results showed that pressure significantly influenced the mass transfer. The membrane flux depended on the mass transfer coefficient (Dtoluene-IL) and the driving force (△P) [START_REF] Zhang | Toluene gas treatment by combination of ionic liquid absorption and photocatalytic oxidation[END_REF]. When increase pressure, the driving force was increased, thus membrane flux boosted. As operating conditions, for one ILM, the absorption capacity was constant due to the same quantity of IL contained. According to the mass of toluene absorbed by ILM under different pressures, higher pressure brought faster absorption rate owing to reaching the same absorption capacity of the ILM at the shorter time consumed.

Therefore, higher pressure has a positive effect on toluene absorbing by ILM. However, it should not be ignored that the increasing pressure also can push ILs into porous of the ceramic membrane resulting in ILs leakage. In this work, it is impossible for IL to enter the porous of the ceramic membrane. The critical entry pressure of the porous membrane can be calculated based on the Young-Laplace equation [START_REF] Dai | Membrane absorption using ionic liquid for pre-combustion CO2 capture at elevated pressure and temperature[END_REF]. According to the contact angle between the IL and the ceramic membrane, surface tension of the IL and pore size of the ceramic membrane, the critical entry pressure is around 55.0 atm. Among all experiments, the operating pressure was lower than the critical entry pressure, which indicated that the IL could not enter the porous of the ceramic membrane resulting in the IL leakage. Flow rate = 0.30 L min -1 , P = 1.07 / 1.12 / 1.17 atm, T = 20 ℃)

Temperature

The temperature is a key factor in removal efficiency for toluene removal by the ILM. The effect of temperature was investigated from 20 to 60 ℃. From temperature. The temperature has negative effects on toluene removal, which has been confirmed by several studies [START_REF] Wang | Study on the absorbability, regeneration characteristics and thermal stability of ionic liquids for VOCs removal[END_REF][START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF][START_REF] Vuong | Determination of the Henry's constant and the mass transfer rate of VOCs in solvents[END_REF]. This is agreed by Henry's law that solubility of gases usually decreases with increasing temperature at around room temperature. Faghihi-Zarandi et al. [START_REF] Faghihi-Zarandi | A new method for removal of hazardous toluene vapor from air based on ionic liquid-phase adsorbent[END_REF]. showed that the absorption capacity was increased from 0 to 20 ℃. For the temperature range from 20 to 60 ℃, the toluene removal efficiency and absorption capacity by ILs were a little bit reduced by temperature increasing. However, when temperature increased from 60 to 120 ℃, the toluene absorption capacities by ILs was decreased sharply because the physical interactions between toluene and the IL such as hydrogen bonds and hydrophobic interaction were decreased in high temperature. In addition, some physical properties of ILs were influenced by temperature. For example, the increasing temperature can reduce the viscosity of ILs. Furthermore, a higher viscosity resulted in a lower gas diffusion coefficient and consequently, higher liquid phase mass transfer resistance [START_REF] Fortunato | Supported liquid membranes using ionic liquids: study of stability and transport mechanisms[END_REF][START_REF] Dai | Combination of ionic liquids with membrane technology: A new approach for CO2 separation[END_REF][START_REF] Koller | Viscosity, Interfacial Tension, Self-Diffusion Coefficient, Density, and Refractive Index of the Ionic Liquid 1-Ethyl-3-methylimidazolium Tetracyanoborate as a Function of Temperature at Atmospheric Pressure[END_REF][START_REF] Zhu | Adsorption and diffusivity of CO2 in phosphonium ionic liquid modified silica[END_REF]. Thus, low temperature (20 ℃) was proposed for toluene removal by ILM. Some studies underlined that there are some environmental risks of ILs, which limits their applications in industrial processes. Stability of ILs into a supported media provides a possibility to reduce the negative effects of ILs. Unfortunately, it is rare studies focus on the utilization of ILs combining with support media for organic compounds gas separation. This is of importance, especially in the purification of exhaust air from industrial processes, to provide safety in atmosphere protection and to protect IL from solid in the gas phase. In our process, the saturated mass of toluene captured by ILM with our proposed operating conditions was 0.224 g-toluene g-IL -1 of [Bmim][NTf2] which in agreement with Bedia's result. In addition, the support ceramic membrane can effectively prevent ILs leakage from causing secondary waste and/or protect ILs from suspended matters. The concept of ILM is closer to the concept of green chemical processes and can be mixed as the function of the VOCs in the effluent.

Industrial Ceramic Membrane

Discussing the effect of the support membrane length, an industrial membrane (the length is 1.178 meter) was registered at room temperature, and the pressure was controlled at 1.00 atm.

This experiment was conducted at room temperature due to the space limitations of the thermostatically controlled chamber. The toluene concentration inlet was kept constant on 70 ppm with 0.10 L min -1 gas flow rate. It is well-known that surface area, the quantity of ILs and gas residence time will be increased with length of membrane increasing resulting in higher absorption. From Figure IV-8(a), concentration toluene outlet increased more slowly than the shorter one. This result indicated that total removal toluene using the long membrane was higher than that of shorter due to the larger contact area and the IL quantity. Around 20 hours, the curve of concentration outlet fluctuated regularly up and down because of the diurnal temperature variation of the day (high temperature) and night (low temperature). This variation in agreement with the effect of temperature discussed before. Lower temperature was benefit for gas absorption on liquid absorbents, however, increase the viscosity of the IL which resists the mass transfer. In addition, as The process of treating toluene with industrial ILMs was connected in series. In this section, an industrial length ILM simulates the process of continuous industrial treatment of a toluene-containing exhaust gas stream. growing steadily when the experiment was stop. This result is evidence that the ILM was not saturated. Toluene absorbed mass grows faster at a higher inlet concentration due to the greater driving force was provided, which agrees with section 3.1. The ILM maintains high separation performance and stability (no IL leakage) even after continuously operating for very long periods (the adsorption process lasts 640 hours).

Conclusions

Based on the absorption capacities of ILs for toluene absorbing, [Bmim][NTf2] was selected as an effective and recyclable absorbent combining with a ceramic membrane for toluene removal. In addition, the ILM contained [Bmim][NTf2] was investigated based on different operating conditions including concentration of toluene inlet, flow rate, pressure and temperature. Results demonstrated that higher concentration boosts the mass transfer due to a higher concentration gradient. Flow rate influenced the contact time between toluene and the IL. When the flow rate is increasing, ILM removal efficiency was enhanced because a higher gas flow rate has more effects on the quantity of gas inlet than the residence time. Higher pressure provided a higher driving force to enhance toluene absorption. Temperature is a very critical factor, which could influence both gas absorption and viscosity of the IL. In the industrial ILM experiment, it was confirmed that temperature changes caused gas concentration outlet variation. The lower temperature was a benefit for gas absorption on liquid absorbent, however, increase the viscosity of the IL, which resistance the mass transfer. Comparison with other studies, [Bmim][NTf2] showed good absorption capacity (0.224 g-toluene g-IL -1 ) for toluene, which is with a good agreement for the ratio mVOC/mIL and published results. Moreover, ILM can effectively reduce the possibilities of environmental risk from ILs because the ceramic membrane can prevent ILs leakage and protect IL from suspended matters in the gas phase. The industrial ILM was tested in an industrial absorption process that ILMs were connected in series.

70 ppm of toluene was treated by a same industrial ILM three times continuously, and then the concentration of toluene was decreased to 12 ppm. This result gives an indication of the industrial application and arrangement of ILMs. During 120h, the ILM can treated this effluent without regeneration. For several times absorption-desorption cycles and over long-time operation (more than 1 000 hours), there was no IL leakage observed. It provides a promising method for using ILs as absorbents for the purification of exhaust gases from industrial processes.

Introduction

Membrane-based absorption processes are widely studied for gases removal from a gas mixture because the membrane provides support for the interface of two immiscible compounds.

In addition, ILs act as absorbents offering high absorption capacity for VOCs (toluene) and humidity based on physical absorption. Thus far, simulation has been used to design the membrane-based absorption processes to reduce the cost of processes. In this work, simulation of ILMs for gases removal (both humidity and toluene) using ILs as liquid absorbents at different operating parameters was developed. A porous ceramic membrane with a molecular weight cut off 1 kDa and porosity of 35 -37% was chosen as the support membrane owes to the good mechanism and thermal stability. Moreover, the effects of operation parameters, such as flow rate, temperature, pressure and concentration of gas inlet, on the gas removal were investigated.

Mass Transfer Coefficients

For a gas-liquid membrane, overall mass transfer was determined by three phases based on three steps of target gas absorption by ILs:

The resistance of the gas phase. The target gas moves from the gas mixture bulk to the porous membrane. In this study, the carrier gas is air. The resistance of the gas phase (Rg) is mainly from the gas boundary layer based on the two-film theory, which is very small comparing to the liquid phase. Therefore, Rg can be neglected [START_REF] Mavroudi | A study of mass transfer resistance in membrane gas-liquid contacting processes[END_REF].

The resistance of the membrane phase. Target gas compounds pass through the porous support membrane reach membrane and liquid interface. Normally, target gas passes through the porous support membrane can be divided into two categories depending on support membrane situations: i) non-wetting; ii) wetting. In this study, only the non-wetting support membrane was discussed. For a not-wetted membrane, the pores of the support membrane were filled with the gas mixture. However, mass transfer resistance mainly comes from the membrane pores. The mass transfer coefficient (Km) of a not-wetted membrane can express as:

𝐾 𝑚 = 𝐷 𝑔 ×𝜀 𝑚 𝛿 𝑚 ×𝜏 𝑚 (V-5)
where εm, δm and τm are the porosity, thickness and tortuosity of support membrane; Dg is the target gas move in the carrier gas (air) at experimental conditions.

The resistance of the liquid phase. Mass transfer resistance is mainly contributed by the diffusion of target gas into the bulk liquid. In this work, the liquid absorbent (ILs) was stable into the liquid channels. Therefore, the liquid phase mass transfer coefficient was regarded as target gas diffusion coefficient in ILs, which can be described as following [START_REF] Baghban | Rigorous modeling of CO2 equilibrium absorption in ionic liquids[END_REF][START_REF] Castillo | Assessment of VOC absorption in hydrophobic ionic liquids: Measurement of partition and diffusion coefficients and simulation of a packed column[END_REF]:

𝐷 𝑔𝑎𝑠-𝐼𝐿 = 7.4 × 10 -8 × (∅×𝑀 𝐼𝐿 ) 0.25 ×𝑇 𝜇 𝐼𝐿 ×𝑉 𝑔𝑎𝑠 0.6 (V-6)
where Dgas-IL is the diffusivity (m 2 s -1 ), T is the temperature (K), MIL is molar mass of the IL (g mol -1 ), µIL is the viscosity of IL (mPa s), and Vm is the molar volumes (cm 3 mol -1 ), ∅ is the association parameter (∅ = 1, because IL acts as the unassociated solvent).

ILs viscosity is temperature dependent can be described [START_REF] Dai | Modelling of a tubular membrane contactor for precombustion CO2 capture using ionic liquids: Influence of the membrane configuration, absorbent properties and operation parameters[END_REF][START_REF] Harris | Temperature and Pressure Dependence of the Viscosity of the Ionic Liquid 1-Butyl-3-methylimidazolium Hexafluorophosphate[END_REF][START_REF] Harris | Temperature and Pressure Dependence of the Viscosity of the Ionic Liquid 1-Butyl-3-methylimidazolium Tetrafluoroborate: Viscosity and Density Relationships in Ionic Liquids[END_REF]:

𝜇 𝐼𝐿 = (1.72 -9.4 × 10 -3 × 𝑇) × 1000 (V-7)
Temperature dependency of Henry's constant of the ILs [START_REF] Dai | Modelling of a tubular membrane contactor for precombustion CO2 capture using ionic liquids: Influence of the membrane configuration, absorbent properties and operation parameters[END_REF][START_REF] Dai | Gas solubility in long-chain imidazolium-based ionic liquids[END_REF][START_REF] Lei | Gas Solubility in Ionic Liquids[END_REF]:

𝐻 = exp (5.006 × 10 2 × 1 𝑇 -3.863 × 10 5 × 1 𝑇 2 ) (V-8)
Above all, the total resistance (Rtotal) should come from three parts including gas bulk, porous membrane, and liquid bulk. According to this study, the mass transfer coefficient of gas bulk was neglected. Therefore, Rtotal of ILM can be expressed [START_REF] Boributh | A modeling study on the effects of membrane characteristics and operating parameters on physical absorption of CO2 by hollow fiber membrane contactor[END_REF][START_REF] Mavroudi | A study of mass transfer resistance in membrane gas-liquid contacting processes[END_REF]:

𝑅 𝑡𝑜𝑡𝑎𝑙 = 1 𝐾 𝑡𝑜𝑡𝑎𝑙 = 𝑅 𝑔 + 𝑅 𝑚 + 𝑅 𝑙 = 𝑅 𝑚 + 𝑅 𝑙 (V-4)
where Rg, Rm and Rl denote the gas, membrane, and liquid phase resistance, respectively. Rm, for a non-wetted membrane, is the resistance to mass transfer in the membrane pores.

According to the operating parameters, mass transfer coefficients are including two parts: porous membrane and liquid bulk. The mass transfer in gas bulk was neglected. These two mass transfer coefficients were calculated. From Figure V-1, the mass transfer coefficient in the IL is much lower than the mass transfer coefficient in the porous membrane, which indicated that the mass transfer resistance mainly came from the liquid phase when the two transfers occur. In addition, in our system, the supported porous membrane was nonwetted, in where the mass transfer coefficient only slightly lower than in gas bulk. It is worth mentioning that in a wetted porous membrane, the mass transfer coefficient should be reconsidered.

Effect of the Length of the Support Membrane:

Increasing the support membrane length could increase the surface area and contact time between target gas and the IL to improve the gas absorption. However, the concentration gradient of target gas will decrease with membrane length, and then, the absorption efficiency decrease. Therefore, the length of the membrane should be optimized according to the separation targets. For the first part on the effect of operating parameters, the length is equal to 0.25 m. For the large removal rate, an industrial length of the membrane (1.178 m) is used (i.e. length of commercial ceramic membranes).

Models Development

Some models were also proposed to correlate and to predict the gases (vapors) uptake by ILs (liquid phases) [START_REF] Francesco | Water sorption by anhydrous ionic liquids[END_REF][START_REF] Arellano | Thermal stability and moisture uptake of 1alkyl-3-methylimidazolium bromide[END_REF]. The classical thermodynamic model non-random two-liquid (NRTL) activity coefficient model has been used successfully to fit gas-IL system [START_REF] Zhao | Vapor pressure measurement for binary and ternary systems containing a phosphoric ionic liquid[END_REF][START_REF] Wang | Vapor pressure measurement for water, methanol, ethanol, and their binary mixtures in the presence of an ionic liquid 1-ethyl-3methylimidazolium dimethylphosphate[END_REF][START_REF] Dahi | Water sorption properties of room-temperature ionic liquids over the whole range of water activity and molecular state of water in these media[END_REF]. Besides, the modified BET multilayer adsorption model [START_REF] Carrete | Theoretical model for moisture adsorption on ionic liquids: A modified Brunauer-Emmet-Teller isotherm approach[END_REF], Wilson [START_REF] Dahi | Supported ionic liquid membranes for water and volatile organic compounds separation: Sorption and permeation properties[END_REF], UNIQUAC [START_REF] Simoni | Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC[END_REF], COSMO-RS [START_REF] Iqbal | COSMO-RS predictions, hydrogen bond basicity values and experimental evaluation of amino acid-based ionic liquids for lignocellulosic biomass dissolution[END_REF][START_REF] Sellaoui | Steric and energetic interpretations of the equilibrium adsorption of two new pyridinium ionic liquids and ibuprofen on a microporous activated carbon cloth: Statistical and COSMO-RS models[END_REF] and other models [START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF][START_REF] Cao | Water Sorption in Functionalized Ionic Liquids: Kinetics and Intermolecular Interactions[END_REF]292] are widely studied to describe the gas vapor sorption in ILs.

Based on the investigations above, a modified two steps gas sorption mechanism by the ILM was proposed for this system. Furthermore, gas sorption by the ILM involves two steps:

passing through the ceramic membrane reach and adsorb on the ILs surface and then absorption into the ILs bulk [START_REF] Lovelock | Water adsorption on a liquid surface[END_REF][START_REF] Rivera-Rubero | Influence of Water on the Surface of Hydrophilic and Hydrophobic Room-Temperature Ionic Liquids[END_REF][START_REF] Klähn | What Determines the Miscibility of Ionic Liquids with Water? Identification of the Underlying Factors to Enable a Straightforward Prediction[END_REF]. Two mechanisms were proposed for the gas sorption process by ILM. The process of gas absorbed by ILM could be described with two steps (Figure V-2). In step 1, gas molecules move from the vapor phase, pass through the porous membrane and then be absorbed on the surface of ILs. During this step, only surface sorption is taking account. In fact, others also happen, but surface adsorption is the main phenomena. (Langmuir model) [START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF][START_REF] Cao | Water Sorption in Functionalized Ionic Liquids: Kinetics and Intermolecular Interactions[END_REF]. In step 2, gas molecules move from the surface to the bulk ILs and diffusion takes place.

In fact, bulk and surface sorption takes place simultaneously until reaching an equilibrium state in this step (1D diffusion model) [292,[START_REF] Rocha | Water Sorption and Diffusivity in [C2C1im[END_REF]. Because the gas absorption from vapor to the surface is faster than the diffusion, the gas sorption is mainly controlled by diffusion. For simplification, the surface sorption was neglected for the whole step 2 process, which was the limiting transfer.

Langmuir Adsorption Model (Step 1)

The Langmuir model reflects the monolayer sorption, and the adsorbed layer is one molecule in thickness [START_REF] Abdelrahim | Supported ionic liquid membranes immobilized with carbonic anhydrases for CO2 transport at high temperatures[END_REF]298]. Langmuir refers to homogeneous adsorption and an equilibrium saturation point where once a molecule occupies a site, no further adsorption can occur [START_REF] Foo | Insights into the modeling of adsorption isotherm systems[END_REF][START_REF] Aljeboree | Kinetics and equilibrium study for the adsorption of textile dyes on coconut shell activated carbon[END_REF][START_REF] Saruchi | Adsorption kinetics and isotherms for the removal of rhodamine B dye and Pb+2 ions from aqueous solutions by a hybrid ion-exchanger[END_REF]. The basic assumptions of the model are following: i) the surface containing the adsorbing sites is a perfect flat plane with no corrugations; ii) the absorbing gas adsorbs into an immobile state; iii) all sites are equivalent; iv) each site can hold at most one molecule; v) there are no interactions between adsorbate molecules on adjacent sites. The gas vapor sorption by almost all of the ILMs as the function of time during the initial part is approximately linear [START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF]. In this case, a constant absorption rate (kL) was assumed for the whole first step process.

It means linear absorption kinetics was proposed for surface sorption step. The equation is expressed as:

𝐶 𝑒 𝑄 𝑒 = 1 𝑄 𝑚 × 𝐶 𝑒 + 1 𝑘 𝐿 0 ×𝑄 𝑚 (V-9)
𝐶 𝑒 = 𝐶 0 -𝐶 𝑡 (V-10)

𝑄 𝑒 = 𝑘 𝐿 × 𝑡 + 𝑄 0 , 𝑡 ≤ 𝑡 0 (V-11)
where kL 0 is the Langmuir adsorption rate constant related to the adsorption energy, Ct is the concentration of gas outlet of the ILM at each time (mg L -1 ), Ce is the adsorbed concentration of gas by IL surface at each time (mg L -1 ), C0 is the initial gas concentration, which is constant in this system (mg L -1 ), Qe is the amount of target gas absorbed at each time (mg), Qm is the max amount of target gas absorbed at saturation (mg), Q0 is the quality of residual in ILM (mg), kL is the adsorption rate (mg min -1 ), t is time (min), t0 is the time-dividing point (min), which depends on the IL types and process conditions.

One-dimensional (1D) Diffusion Model (Step 2)

The 1D diffusion model was proposed to determine the binary diffusion coefficient for a gas dissolving into an IL, and the volume of the IL is constant during the process [START_REF] Rocha | Water Sorption and Diffusivity in [C2C1im[END_REF][START_REF] Shiflett | Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids[END_REF][START_REF] Santiago | From kinetics to equilibrium control in CO2 capture columns using Encapsulated Ionic Liquids (ENILs)[END_REF]. The basic assumptions of the model are following: i) no phase changing occur; ii) for one experiment the temperature and pressure remain constant (once gas dissolving occur, the system pressure and IL density are kept constant); iii) the IL-gas system is a dilute solution where the thermophysical properties remain constant; iv) gas dissolves through a vertical diffusion process. The 1D mass diffusion can be expressed as follows:

𝜕𝐶 𝜕𝑡 = 𝐷 𝜕 2 𝐶 𝜕𝑧 2 (V-11)
initial condition: C = C0, when t = 0, and 0 < z < L; boundary conditions: C = Cs, when t > 0, z = 0;

𝜕𝐶 𝜕𝑧 = 0, at z = L.
Quantity of gas dissolved at a specified time is the total mass of dissolved gas in the IL and not the mass profile in the z-axis. The mass of dissolved gas at a given time can be express:

𝐶 𝑚 = ∫ 𝐶𝑑𝑧/𝐿 𝐿 0 (V-12) 𝐶 𝑚 = 𝐶 𝑠 × [1 -2(1 - 𝐶 0 𝐶 𝑠 ) × ∑ exp(-λ 𝑛 2 ×𝐷×𝑡) 𝐿 2 ×λ 𝑛 2 ∞ 𝑛=0 , 𝑡 > 𝑡 0 (V-13)
where Cm is mass of target gas absorbed by per gram of ILs at each time (mg-toluene g-IL -1 ), C0 is the initial concentration (Qm in Step 1) (mg-toluene g-IL -1 ), Cs is the saturate mass of target gas absorbed by per gram of ILs (mg-toluene g-IL -1 ) (Cm ≤ Cs), D is the diffusion coefficient of gas vapor in the selected IL at operational conditions (m 2 s -1 ), t is time (sec), L is the height of IL in one channel of ILM (m) (as Figure V-3 shown). λ = (n+1/2)*π/L (n = 15 for convergence because the summation in Cs will less than 10 -12 ): this equation is an infinite summation, only initial time periods are sufficient in applications [START_REF] Shiflett | Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids[END_REF]).

Effects of Operating Conditions on Humidity Absorption

For humidity absorption, [Bmim]Br was selected as an absorbent ([Bmim]Br is regarded as a liquid sorbent at experimental conditions). Since the water sorption, the water and ILs interactions and the correlations between the sorption and interactions are very significant.

Effects of structural factors of ILs affecting the water sorption by ILs are investigated widely.

Water interacts with the anion, which is a main factor to determine water sorption, followed by the length of the alkyl side chain at the cation and cation type [START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF][START_REF] Tran | Absorption of Water by Room-Temperature Ionic Liquids: Effect of Anions on Concentration and State of Water[END_REF][START_REF] Freire | An overview of the mutual solubilities of water-imidazolium-based ionic liquids systems[END_REF][START_REF] Roth | Ionic Liquids Can Be More Hydrophobic than Chloroform or Benzene[END_REF][START_REF] Seddon | Influence of chloride, water, and organic solvents on the physical properties of ionic liquids[END_REF].

Furtherment, some researchers demonstrated that water absorbed in ILs due to attractive physical forces like hydrogen bonding and van der Waals force [START_REF] Cuadrado-Prado | Experimental measurement of the hygroscopic grade on eight imidazolium based ionic liquids[END_REF]292]. Besides the structure of ILs, the external factors also have a strong influence on the water sorption. In this study, we focus on studying the influence of operating parameters including RH inlet, pressure, flow rate and temperature.

Relative Humidity (RH) Inlet

RH is the amount of water vapor in a mixture of air and water vapor. The water sorption in [Bmim]Br at 32 ℃ and 1.0 atm with RH inlet of 35% and 45% were determined. With the 0.5 L min -1 gas flow rate, the amount of water vapor inlet at operating conditions were 5.91 and 7.60 mg min -1 for 35% and 45% of RH. When increasing the RH inlet, a larger amount of water vapor inlet to the membrane during the same time, thus the ILM can be hydrated easily, leading to less time to reach surface sorption equilibrium [START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF][START_REF] Cao | Water Sorption in Functionalized Ionic Liquids: Kinetics and Intermolecular Interactions[END_REF]. As shown in Table V shows the parameters of 1D diffusion simulation (step 2). The saturation mass of water absorbed by ILM has a little bit increased with the concentration of humidity inlet increasing due to a higher quantity of water inlet at the same time. However, the higher concentration inlet has no significant influence on water vapor diffusion into the IL bulk because of the same diffusion coefficient (Dwater-IL) and the only 6% difference of saturation water quantity (msaturation) between 35% and 45% RH inlet. Therefore, the concentration of humidity inlet mainly affects surface adsorption.

Table V-

Pressure

When RH inlet and temperature are constant, higher system pressure means higher driving force for water molecules [START_REF] Chen | Absorption of methylbenzene in 1-butyl-3methylimidazolium ionic liquids[END_REF][START_REF] Kumar | Fouling control on microfiltration/ultrafiltration membranes: Effects of morphology, hydrophilicity, and charge[END_REF]. Theoretically, the increase in operating pressure could reduce the mass transfer resistance in step 1, as the gas sorption rate increase with the increase of pressure. It can be clearly seen that the ILM under higher pressure was much faster to reach the surface sorption equilibrium. As well as, from the Table V-3, Langmuir model (step 1) results, the surface adsorption saturation (Qm) are similar values with these three pressure systems. This result means that the system pressure only increases the sorption rate during the first step. However, during step 2 (Figure V-5 and Table V-4), for water vapors diffusion in the ILs bulk showed a different result when increasing system pressure. In addition, the gas solubility increases with operating pressure increasing, which indicated that the equilibrium concentration of water vapor in the IL was enhanced with pressure increasing. Furthermore, the molar volume of the water vapor will be decreased with pressure increases, which result in a faster gas diffusion rate into bulk IL. The diffusion process is the rate-determining step, above all, higher pressure has positive effects on gas absorption by the ILM because both diffusion rate and equilibrium concentration are boosts.

Flow Rate

To investigate the influence of feed flow rate on water sorption, the ILM was investigated at an inlet flow rate from 0.50, 1.00 to 1.50 L min -1 and other conditions kept constant.

Increasing gas flow rate could enhance the mass transfer in the gas phase, which is a good agreement with the duration of step 1 (as shown in Table V-5). As Figure V-6 and Table V-6 shown, at a low flow rate, the ILM efficiency was high. Because at low flow rate the water vapor residence time on the sorbent (ILs) was higher compared to a high flow rate, resulting in effective interaction of water molecules with the IL sorbent [START_REF] Severa | SO2 sorption by activated carbon supported ionic liquids under simulated atmospheric conditions[END_REF]. As well as increase the feed flow rate was increasing the quantity of water inlet at the same time, which reduced the mass transfer coefficient of the liquid phase. This result exhibited that the equilibrium concentration and diffusion rate were increased with flow rate increases. Therefore, a high flow rate is a benefit of humidity absorption by ILM during our testing range. As

Temperature

The effect of temperature on the ILM humidity sorption is shown in Figure V-7, Table V-7 and V-8. In this study, the sorption analysis was performed at 25, 32 and 39 ℃ whilst maintaining other parameters constant. As shown in Table V-7, the sorption capacity and diffusion rate were lower at low temperature. Viscosity factor acts the key role for gas diffusion into the bulk IL [START_REF] Freire | Mutual Solubilities of Water and Hydrophobic Ionic Liquids[END_REF][START_REF] Freire | Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids[END_REF][START_REF] Freire | Mutual Solubility of Water and Structural/Positional Isomers of N -Alkylpyridinium-Based Ionic Liquids[END_REF]. Moreover, from the Figure V-8, the viscosity of selected IL ([Bmim]Br) decrease with temperature increasing, which results in a faster water vapor diffusion in the ILs bulk [START_REF] Harris | Temperature and Pressure Dependence of the Viscosity of the Ionic Liquid 1-Butyl-3-methylimidazolium Hexafluorophosphate[END_REF][START_REF] Zhou | Densities and Viscosities of 1-Butyl-3-methylimidazolium Tetrafluoroborate + H2O Binary Mixtures from (303.15 to 353.15K[END_REF][START_REF] Jacquemin | Density and viscosity of several pure and watersaturated ionic liquids[END_REF][START_REF] Martins | Densities, viscosities and derived thermophysical properties of water-saturated imidazolium-based ionic liquids[END_REF]. It has been reported that temperature affects the viscosity of pure as well as saturated in the water of ILs [START_REF] Tshibangu | Density, Viscosity and Conductivity Study of 1-Butyl-3-Methylimidazolium Bromide[END_REF][START_REF] Jacquemin | Density and viscosity of several pure and watersaturated ionic liquids[END_REF]. In this study, the [Bmim]Br was regarded as a liquid sorbent at the testing temperature range. Generally, the water vapors prefer to stay in the gas phase under high temperature, which indicated that the saturation concentration of water was smaller with a higher temperature. Figure V-7 shows that at higher temperature ILM more accessible to reach water sorption equilibrium. This result exhibited that the high temperature has the negative effect on humidity absorption by the ILM.

Table V-

Effects of Operating Conditions on Toluene Absorption

For toluene absorption, [Bmim][NTf2] was selected as an absorbent. The chemic-physical properties of the liquid absorbent effect the toluene absorption, besides, the effects of different operational parameters on toluene removal by ILMs also significant. In this section, the sorption mechanism for toluene absorption by ILMs with different operating conditions were discussed.

Toluene absorption by ILMs was simulated with two steps model following simulations: i) toluene absorbed by the ionic liquid was physical absorption, and there was non-reacting occurs;

ii) the diffusion coefficients of toluene into the IL were calculated by the equation V-6.

Based on this diffusion coefficient and operating conditions, the ILM saturated mass and time were predicted based on 1D model. The saturated time was the ILM reached 95% of the maximum mass. The 1D model indicated that when t → ∞, Cm was equal to Cs. Within the engineering permissible range (± 5%), when the mass of toluene absorbed by ILM reached 95% of the maximum mass, the ILM could be regarded as saturation at the given operating conditions.

Concentration Inlet

The ILM was registered at 0.30 L min -1 flow rate with different concentrations inlet 50 and 70 ppm of toluene. Quantity of toluene inlet were respectively 0.057 and 0.080 mg min -1 at operating conditions (20 ℃ and 1.07 atm). For the surface adsorption (step 1), toluene molecules passed through the porous ceramic membrane and reached the IL surface. As Table V-9 shown, a higher concentration of toluene inlet resulted in a faster surface absorption rate (kL) because of a higher driving force provided. Therefore, it was clear that the first step took longer time with lower concentration inlet. For gas diffusion into the liquid phase (step 2), this step was a rate control step. The diffusion coefficient was a key parameter for the second step.

According to the Wilke-Chang equation (equation V-6), the diffusion coefficient of toluene into ILs was influenced by the temperature and pressure [START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF]. From Figure V-7, the simulated results were fit well on experimental results, and it demonstrated that the diffusion coefficient was not affected by concentrations. It was observed that ILM absorbed toluene much faster with higher concentration inlet, because the increasing concentration of toluene inlet, the mass transfer resistance of the liquid phase was reduced. Based on this diffusion coefficient and operating conditions, the ILM saturated mass and time were predicted, as shown in Table V-10.

The result confirmed that the ILM under higher concentration inlet took less time to reach its saturation, which matched the experimental data.

Pressure

To investigate the pressure effects, the ILM was tested with different pressures from 1.07 to 1.17 atm and other parameters constant. For gases absorbed by a liquid sorbent, the pressure was mainly influenced by the gas phase. As above mentioned, the difference of toluene pressure between the gas phase and liquid phase (△P) provided a driving force for mass transfer. For both surface adsorption (step 1) and diffusion (step 2), Table V-11 and V-12 showed that the higher pressure increased the sorption capacities, but the sorption rates kept constant. The ILM took longer time in surface adsorption with higher pressure (Table V -11). However, it was inversed in diffusion. bulk with different pressures from the experimental results. With pressure = 1.17 atm, at the beginning of diffusion, the simulated line is not in good agreement with the experimental result.

Higher pressure results over saturated of surface adsorption and excessed gas vapors cannot be diffusion into the bulk IL efficiently. Therefore, parts of gas vapors desorbed from the surface of the IL and exit [START_REF] Koller | Viscosity, Interfacial Tension, Self-Diffusion Coefficient, Density, and Refractive Index of the Ionic Liquid 1-Ethyl-3-methylimidazolium Tetracyanoborate as a Function of Temperature at Atmospheric Pressure[END_REF]. Table V

Flow Rate

To study the influence of flow rate on toluene sorption, the ILM was investigated at inlet flow rates as 0.10, 0.15 and 0.30 L min -1 and other conditions were constant. The gas flow rate influence on both contact time and quantity of target gas inlet when the concentration of gas kept constant. The surface adsorption parameters were shown in Table V-

Temperature

The effects of temperature were tested in a range from 20 to 60 ℃, and results are shown in Figure V-12. Generally, increasing the temperature will reduce gas solubility, which has a negative influence on gas removal [START_REF] Dai | Modelling of a tubular membrane contactor for precombustion CO2 capture using ionic liquids: Influence of the membrane configuration, absorbent properties and operation parameters[END_REF][START_REF] Dai | Gas solubility in long-chain imidazolium-based ionic liquids[END_REF][START_REF] Lei | Gas Solubility in Ionic Liquids[END_REF]. Moreover, increasing temperature will also decrease the liquid viscosity (Table V-15) and enhance the gas diffusion, which has a positive influence on gas removal [START_REF] Vuong | Determination of the Henry's constant and the mass transfer rate of VOCs in solvents[END_REF][START_REF] Dai | Modelling of a tubular membrane contactor for precombustion CO2 capture using ionic liquids: Influence of the membrane configuration, absorbent properties and operation parameters[END_REF][START_REF] Myers | High temperature separation of carbon dioxide/hydrogen mixtures using facilitated supported ionic liquid membranes[END_REF]. The effects of temperature on toluene removal by ILM were discussed both on surface sorption and diffusion. For the surface adsorption, the temperature only affects the gas solubility. From Table V-16, the surface sorption parameters showed that the surface adsorption capacity was slightly increased. At the same time, the surface adsorption rate also enhanced with temperature increasing due to toluene molecular motion increasing. From the pressure of gas diffusion into liquid bulk (Figure V-12 and Table V-17), it is observed that the effect of temperature on toluene absorption is negative. Higher temperature resulted in a higher residual toluene concentration on the liquid surface, which reduced mass transfer resistance in the liquid. In addition, the viscosity of the IL was reduced resulting mass transfer resistance reduction. The toluene concentration differences outlet of ILM over the testing temperature range was not large because the temperature effect on toluene removal was limited. Therefore, the optimized temperature selected should consider based on both gas solubility and viscosity of the liquid.

Toluene Absorbed by the ILM on Proposed Operating Conditions

Toluene absorbed by an ILM at proposed operating conditions was studied on an experiment. The proposed operating conditions are concentration of toluene inlet = 70 ppm, flow rate inlet = 0.10 L min -1 , pressure = 1.17 atm and temperature = 20 ℃. According to the experimental result, the ILM needed 32 hours to reach saturation at proposed operating conditions. Therefore, the simulated process just used to fit the ILM saturation. As Figure V-13

shown, the simulated results were agreed to experimental results both surface adsorption (step 1) and diffusion (step 2). From the insert figure (step 1), surface adsorption rate (kL) was 0.0008, which was higher than 0.10 L min -1 gas flow rate and 1.07 atm (kL = 0.0003) but lower than 0.30 L min -1 gas flow rate and 1.17 atm (kL = 0.0012). This result indicated that the gas flow rate played a relatively important role than the system pressure. Surface saturated adsorption (Qm) was 0.25*10 -3 g-toluene g-IL -1 . For gas diffusion into bulk IL (step 2), the diffusion coefficient (Dtoluene-IL) was 4.12*10 -11 m 2 s -1 , which was same with 1.17

Industrial Ceramic Membrane

In the experimental part, the use of an industrial ceramic membrane on ILM absorption performance was also discussed. However, the 1D diffusion model could not be used to fit this result due to the temperature variation of the day (high temperature) and night (low temperature).

The difference between the highest and lowest temperature is around 10 ℃. One critical assumption of the 1D model is temperature and pressure keep constant during one experiment.

Because of the thermostatically controlled chamber limited, the ILM with long support membrane could not be placed into the chamber, resulting in temperature variation. In addition, the window of the testing room always kept open during the whole experiment due to safety.

These factors caused the 1D model could not be used to fit and calculate the saturation mass (Cs) and diffusion coefficient (D) based on a longer support membrane.

Effects of Different Parameters of the 1D model on Simulated

Results

The 1D diffusion model was first obtained and used to analyze gas-IL pairs by Shiflett et al. [START_REF] Shiflett | Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids[END_REF] The saturated concentration (Cs) and diffusion coefficient (D) can be calculated at the given temperature and pressure. Researchers indicated that when the critical parameters (e.g.

the critical pressure and temperature of pure compounds) are not available for the cubic equation of state (EOS) [START_REF] Yokozeki | Solubility of Refrigerants in Various Lubricants[END_REF], this simple diffusion model is good enough to fit and analyze time-dependent absorption data, especially binary diffusion coefficients of gas in the ionic liquid. This model was widely used and confirmed proper to analyze binary diffusion coefficients of any dissolving gas in the ILs [START_REF] Castillo | Assessment of VOC absorption in hydrophobic ionic liquids: Measurement of partition and diffusion coefficients and simulation of a packed column[END_REF][START_REF] Anderson | Measurement of SO2 Solubility in Ionic Liquids[END_REF][START_REF] Bara | Guide to CO2 Separations in Imidazolium-Based Room-Temperature Ionic Liquids[END_REF][321]. It should be mentioned that the parameter of n in this model is for convergence, which is not a sensitive parameter. In our case, n = 15 because when n is greater than 15, the fit result is no longer improved and the value of D and Cs are essentially unchanged. On the contrary, this model is very sensitive in some parameters, for example, the height of liquid sorbents (L), the initial value of the initial concentration (C0), numbers of experimental data (sufficient time of an experiment). Castillo et al. [START_REF] Castillo | Assessment of VOC absorption in hydrophobic ionic liquids: Measurement of partition and diffusion coefficients and simulation of a packed column[END_REF] also found that some sensitivity parameters of this diffusion model. Unfortunately, they made a mistake when they used the wrong formula for this model.

Effect of the height of liquid sorbents (L):

the simulated results are very sensitive to the height of liquid sorbents [START_REF] Shiflett | Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids[END_REF]321]. The author mentioned that the simulated saturation mass of gas absorbed would be increased with increasing liquid sorbent height [START_REF] Shiflett | Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids[END_REF]. This sample diffusion model was established based on one important assumption: the gas-dissolved liquid is a highly dilute solution. In this case, the volume expansion from dissolved gas was ignored.

This factor could be well avoided when the gas-liquid pair and liquid sorbent container were decided. For example, the gas usually dissolved small quantity into the liquid sorbent, which could not cause significant volume expansion of the solution. Moreover, once the container and amount of liquid sorbent were decided, the height of liquid sorbent could not be changed during the experiment.

The initial value of concentration (C0):

For the initial value of concentration (C0), the author was clearly mentioned that C0 should be known when using the 1D model to analyze experimental data [START_REF] Shiflett | Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids[END_REF]. However, the analysis using Mathematica requires nonlinear regression [START_REF] Stephen | The MATHEMATICA ® Book[END_REF], and the best fitting could be obtained by giving a proper initial value for C0.

In this study, all the initial value used to fit the 1D model was calculated from the Langmuir model (step 1).

Numbers of experimental data (experimental time):

The effect of numbers of experimental data on simulated results was first discussed. In this part, the ILM studied on proposed operating conditions was used to discussed (section 5. Therefore, it is very essential to ensure that using sufficient experimental data to calculate the final saturated concentration (Cs) by 1D diffusion model.

Conclusions

The aim of this chapter is to study the ILM for gas absorption process including humidity and toluene. A comprehensive two steps mass transfer model was developed and solved different gas absorption processes with non-wetted conditions and the selected IL as an absorbent. The effects of operating parameters on gases removal were systematically discussed and evaluated. Results show that for an ILM based on physisorption based ILs, the liquid side resistance is the limiting factor for the gas overall mass transfer due to its much higher than the gas and membrane side resistances. The gas flow rate and concentration of gas inlet have a large impact on gas removal. These are mainly contributed to the driving force based on the concentration gradients. The operational pressure should not too high to a wet membrane, which will result in mass transfer coefficient in porous membrane increasing and ILs leakage. The temperature has influenced on gas solubility and liquid viscosity. Liquid viscosity has a relatively smaller effect on gas absorption by ILs than the gas solubility.

In addition, the two steps model can be used to predict membrane absorption performances. For humidity removal, based on this study optimized conditions such as relative humidity inlet was 45% with 0.10 L min -1 flow rate and pressure and temperature are 1.20 atm and 25 ℃, the humidity saturation capacity of the ILM was 0.142 g-water g-IL -1 of the [Bmim]Br. For toluene absorption, the toluene absorption capacity of the ILM was 0.224 g-toluene g-IL -1 of

[Bmim][NTf2] with the optimized operational conditions based on our experiments including the concentration of toluene inlet is 70 ppm with 0.10 L min -1 , and pressure and temperature are respectively 1.17 atm and 20 ℃. For the surface adsorption (step 1), the saturation concentration was around 0.18*10 -3 g-toluene g-IL -1 , which was not affected by the operating conditions. For the diffusion (step 2), the ILM absorption capacity of toluene was around 0.224 g-toluene g-IL -1 using [Bmim][NTf2] as an absorbent. This value also confirmed by experimental result. It should be mentioned that the 1D diffusion model is very sensitive on some parameters such as the height of liquid sorbents, initial values of concentration and the experimental time (experimental data). Special emphasis on reconstituted experimental data is necessary to obtain accurate fitting results. Simulated saturation concentration will be underestimated when the experimental data is insufficient. For example, when the experimental data is enough (around 120 000 points), the simulated saturated concentration (Cs) is the agreement with the stat-of-the-art result, and that value reaches to the maximum adsorption capacity of the selected IL. Conversely, when the experimental data was not enough (only 60 000 points), the simulated Cs was heavily underestimated, and the maximum reach to 40% underestimated for the same experiment. According to the simulation and experiment results, the ILMs can be considered as promising methods for gas capture at proper pressure and temperatures by optimization of operation parameters, absorbents and support membranes properties.

A new hybrid process, membrane-ionic liquid (ILM), was developed for gas or liquid treatment. This ILM combines the advantages of ILs and ceramic membranes. For example, the ILM exhibits the thermal, mechanical and chemical stability of ceramic membranes for long-

Effect of gas concentration inlet.

Gas concentration inlet mainly influences on the amount of target gas inlet the ILM. Higher gas concentration inlet provides a higher quantity of gas inlet, which results in a bigger difference of gas concentration between the gas phase and liquid phase. For humidity removal, 35% and 45% relative humidity inlet were studied on the effects of gas concentration let. Results indicated that 45% relative humidity inlet was enhanced mass transfer. For toluene removal, 50 ppm and 70 ppm of toluene inlet were discussed. The same results were obtained that higher concentration provided a higher mass transfer, which can reduce experiment time effectively. In addition, other factors also should take into accounting, for example, the measure ranges of detecting devices and energy consumption.

Effect of gas flow rate. Flow rate affects both contact time and the quantity of gas.

Generally, higher flow rate provides a larger quantity of gas inlet when gas concentration keeps constant. The contact time between the target gas and the selected IL will be decreased with the flow rate increases. It is important to strike a balance between the contact time reduction and mass of gas inlet increment when the flow rate is increasing. Among the testing ranges of both humidity and toluene removal, the relative lower flow rate was proposed. 0.50 and 0.10 L min - 1 flow rate were proposed for humidity and toluene removal.

Effect of pressure. Pressure provides a driving force for gas absorbed by liquid sorbents.

Higher pressure results in a higher driving force which benefits to gas absorption. In addition, higher pressure could surpass the critical entry pressure of the porous support membrane, which results in a higher mass transfer resistance of membrane phase and the leakage of ILM.

According to the experimental parameters and physicochemical properties of solvents, the slightly higher pressure could enhance the gas absorption. The pressure ranges tested in this article also take practical industrial conditions into account. Moreover, the IL leakage from the ILM was not observed on the different pressures even for long-time operation.

Effect of temperature. High temperatures can enhance the thermal motion of gas molecules, which decreases the mass transfer of gas phase and membrane phase (no wetted membrane). Moreover, the viscosity of liquid solvents also is reduced with higher temperature resulting in the mass transfer coefficient of liquid phase decrement. However, a higher temperature can reduce the gas solubility in ILs. According to experiments, the solubility of gases in a liquid solvent acts a key factor on gas absorption by ILMs. Low temperature is favorite on gas removal by this ILMs.

Effect of other parameters. For humidity removal, the position of gas channels was also studies. The experiment was lanced at same operating conditions with the same quantity of the IL. Results showed the position of gas channels influenced the absorption rate of the ILM, but the absorption capacity of the ILM was not affected by the gas channels position for constant parameters. Because the number of channels for the gas pass was constant, the contact area was the same. For toluene removal, the contact area between gas and sorbents was researched by using an industrial ILM. The increase of the length of the membrane, using an industrial membrane, results in both surface area and residence time increasing, which is an advantage for toluene removal. Furthermore, three industrial ILMs were connected in series to continuous treatment of toluene. 70 ppm of toluene passed through three industrial ILMs in succession and the concentration was eventually reduced to 12 ppm. During 120 h, the ILM reached the maximum value of the stabilized outlet concentration for these three experiments. The ILM operated four times and ultra-long absorption-desorption cycles (more than 1 000 hours) without any additional treatments during the cycle interval, which still maintains the high absorption capacity and stability. This result provides a good guide to the development of ILMs application from lab scale to industrial scale.

Regeneration and stability of ILM.

The ILM can achieve regeneration by a simple process.

The polluted ILM is carried out at the same operating conditions with absorption, but the feed stream changed to purified dry air. After several times absorption and desorption, the absorption capacity of ILM was not clearly reduced. High temperature and low pressure are favorable for the desorption process. This result exhibit that ILM can be regenerated by a simple process, and it is stable for long-time operation because IL leakage of ILM was not observed during the longtime operation. For the industrial length membrane testing, the one adsorption process operates for up to 160 hours. Moreover, one ILM was investigated several times absorption/desorption continuously for three weeks, and the ILM retains its high adsorption performance and stability.

In addition, a two-step model was proposed to simulate the experimental data and calculate the saturation station of the ILM at given operating conditions. The two-step model indicated For the 1D model (step 2), the simulated results are very sensitive on the height of liquid solvents, the initial concentration of gas absorbed and the numbers of experimental data. If the experimental data are insufficient, the fitted results will be underestimated. According to our experimental results, the simulated saturation concentration of the ILM is underestimated by up to 40% when the experimental results are not enough.

To conclude, all the above indicates that one act upon several parameters to enhance gases absorption by ILMs. According to the experimental and modeled results, the ILMs can be considered as promising devices for gas capture efficiently by optimization of operating parameters, properties of liquid absorbents and support membranes. Consequently, the challenge is more to define the requirements of a specific application for gases absorption by ILMs and them find an absorbent allowing the best trade-off.

The research on gas or liquid separation using membranes contained ILs is far from exhausted and still represents the object of research of many groups. Some thoughts on directions of research related to the gas or liquid separation using ILs and membranes are proposed.

Although the ILM can exhibit good gas separation performances on the laboratory-scale, discussed are needed to evaluate its capability for larger applications. It is not simple to use industrial ILM. The arrangement of membrane modules should be a detailed discussion. In particular, the ILMs can be series or/and parallel connected to reach the specific separation tasks. Moreover, it is possible to mix different ILs in the same membrane or in the same module as the function of the number of pollutants. The membrane area can be increased, but in this case, the channel diameter decreases, and it will be necessary to optimize the filling of the channels. The industrial length membrane will be tested during very long-time operation, and this ILM showed stabile enough for regeneration several times. In addition, these results provide a reference for the calculation of the capital and operating expenditures associated with the target application.

In the presented work, the absorption of gases (humidity and toluene) from a binary mixture were studied. The only potential competitive absorption considered was dry air. It could thus be interesting to extend that study to the absorption of gases mixtures and separation of industrial gases. For example, the effects of the humidity on the VOCs removal, CO2 / CH4 / H2S mixture and others. This could provide some interesting information on the selectivity of the ILM described.

In addition, the applications of ILMs also can be extended to liquid-liquid extraction. ILs as a membrane solution can be utilized for liquid separation by using ILMs. The instability of ILMs on liquid separation should be addressed. For example, the hydrophilic IL [Bmim]Br as a membrane solution was used to extract water from methanol aqueous solution based on the difference of solubility on the IL. Because of the IL loss heavy, a good removal was not obtained.

ILMs are still attractive on liquid-liquid extraction because they combine the process of extraction and stripping. The ILMs can be used in harsh chemical conditions due to the chemical stabile of the ceramic membrane. Moreover, ILs as a membrane solution can be utilized for liquid separation by using an ILM without any carriers.

The sustainability of the ILMs is in part dictated by the possibility of its regeneration or recycling. The first option relies on the fact that products of gas separation or purification can be removed without or with a minor alteration of the absorbents. According to results, a higher temperature could help to ILMs regeneration. Due to the physical absorption between gases and ILs, this might be possible.

Gas-liquid contactors, especially containing ILs as absorbents, are widely studied.

However, it is mainly investigated on CO2 absorption. It also could be interesting to use gasliquid contactors absorption of VOCs, or other gas and liquid mixtures. The ILM also can be used as a contactor achieving separation of gas or liquid mixtures. Effects of some parameters, such as gas flow rate, temperature and pressure, on PID sensor response were tested. From above results, sensor response on a certain concentration of toluene has a sight change according to gas flow rate and temperature. Considering the error range of this sensor (± 10%), the differences could be ignored. The pressure has not affected on sensor response. Therefore, this PID sensor can be used to detect on gas concentration changing before and after the ILM.

List of Figures

  separation processes. For each process, the treatment of concentration and flow rate ranges are shown in Figure Ⅰ-2.

Figure I- 1 .

 1 Figure I-1. Main VOCs removing and CO2 separation processes

Figure I- 2 .

 2 Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)]

Figure I- 3 .

 3 Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56]

Figure I- 4 .

 4 Figure I-4. Common organic cations of ILs

Figure I- 5 .

 5 Figure I-5. Schematic of SILMs[START_REF] De Los Ríos | A SEM-EDX study of highly stable supported liquid membranes based on ionic liquids[END_REF]

  used a carbon-graphitic carbon nanocomposite membrane to support imidazolium-based RTILs (1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][TNf2], n = 2, 4, and 6). This supported membrane greatly enhanced the stability of SILMs. The SILMs can operate under transmembrane pressures much higher to 1000 kPa without degrading their separation performances. For the polymeric membrane as support, Nylon, Polypropylene (PP), Polyvinylidene fluoride (PVDF), Polytetrafluoroethylene (PTFE) and Polysulfone (PS), are widely used to prepare SILMs.

  only 30% and 20% IL loss with 5 wt% tributylmethylphosphonium formate ([P444][formate]) and tributylmethylammonium formate ([N444][formate]) at 10 bars after 12 hours. Moreover, there were even not loss of ILs for di-iso-propyl 1-alkyl-3-methylimidazolium bistriflamide ([DIP-C4mim][NTf2]) and 1-alkyl-3-methylimidazolium bistrifamide ([C4mim][NTf2]) at the same operating conditions.

Figure I- 6 .

 6 Figure I-6. Schematic of polymer membranes and ILPMs[START_REF] Alkhouzaam | High-pressure CO2/N2 and CO2/CH4 separation using dense polysulfone-supported ionic liquid membranes[END_REF]

Figure I- 7 .

 7 Figure I-7. Schematic of ILMMMs selective separation of toluene[START_REF] Bhattacharya | Synthesis and characterization of ionic liquid based mixed matrix membrane for acid gas separation[END_REF]

Figure I- 8 .

 8 Figure I-8. Hollow fiber supported ILMs by Zhang et al.[START_REF] Zhang | Extraction separation of toluene/cyclohexane with hollow fiber supported ionic liquid membrane[END_REF]

Figure II- 1 .

 1 Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM)

Figure II- 2 .

 2 Figure II-2. The schematic diagram of the test bench

Figure II- 3 .

 3 Figure II-3. The schematic diagram of the gas and humidity generation system

Figure II- 4 .

 4 Figure II-4. The schematic diagram of the humidity removal process

Figure II- 5 .

 5 Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane

Figure Ⅱ- 5 (

 5 Figure Ⅱ-5(b).This experiment aims to check the porous support membrane could not absorb toluene. The same operating conditions with the first experiment, pressure and flowmeter worked well, and each parameter displays normally. In order to eliminate the influence of all other possible factors, the real ILM was recreated maximally in the following two conditions:

Figure II- 6 .

 6 Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃)

Figure II- 8 .

 8 Figure II-8. The schematic diagram of VOCs removal process

Figure II- 9 .

 9 Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and 5 V (voltage supply)

Figure II- 10 .

 10 Figure II-10. The different measure ranges of VOCs sensor

  The data is showing in Figure Ⅱ-11.

Figure II- 11 .

 11 Figure II-11. VOCs sensor calibration for toluene

  ∆P represents the critical entry pressure (breakthrough pressure), γL, θ and σ represent the surface tension of the liquid, the contact angle between the liquid phase and the membrane and the membrane pore diameter, respectively.The humidity and VOCs removal experiments are carried out in a continuous green process and discussed the effects of different operating parameters. The ranges of different operating parameters are summarized in Table Ⅱ-4.

5 . 1

 51 ILs for Humidity RemovalAmong the available ILs, 1-butyl-3-methylimidazolium bromide ([Bmim]Br), 1-butyl-3methylimidazolium hexafluorophosphate ([Bmim][PF6]), and trihexyl(tetradecyl)phosphonium chloride ([3htdp]Cl) were selected in this study for humidity removal. All ILs used in this work was purchased from Solvionic (Toulouse, France). They have been chosen for their hydrophilic-hydrophobic behaviors and their viscosity properties. As far as the selection of IL was concerned, water solubility was an important factor for consideration. The rate of water solubility in an IL is governed by many factors including the operating pressure, temperature and chemical structure of ILs[START_REF] Kamimura | Solubility-switchable Ionic Liquids: A Control of Hydrophilicity and Hydrophobicity Using a Protective Group[END_REF][START_REF] Restolho | Moisture Absorption in Ionic Liquid Films[END_REF][START_REF] Cao | Water sorption in ionic liquids: kinetics, mechanisms and hydrophilicity[END_REF][START_REF] Francesco | Water sorption by anhydrous ionic liquids[END_REF]. According to previous studies, the solubilities of an IL are primarily defined by the anion, followed by the cation alkyl side chain length. Regarding cations, short and mono-branched alkyl chains are recommended for increasing the miscibility of ILs with water. Higher electronic acidity of the cation is preferable for achieving higher water solubility[START_REF] Cammarata | Molecular states of water in room temperature ionic liquids[END_REF][START_REF] Tran | Absorption of Water by Room-Temperature Ionic Liquids: Effect of Anions on Concentration and State of Water[END_REF][START_REF] Bowen | Fundamentals and applications of pervaporation through zeolite membranes[END_REF]. According to the mutual solubilities of water and ILs, the anions were classified into three families. Group 1 comprises decanoate, acetate, halogen, alkyl-phosphinate /phosphate/sulfonate and sulfate, which usually have large miscibility with water.Group 2 has intermediate solubility of ILs with water. It includes fluoroalkyl-phosphinate, fluoroalkylsulfonate, and polar borates. Group 3 contains the most hydrophobic anions, namely the less polar borates, [PF6], [AsF6], [SbF6], (fluoroalkylsulfonyl)-amide, -imide, -methane, -methide and fluoroalkyl-phosphate [210]. Based on those researches, the hydrophobicity of the anions for imidazolium-based ILs increases in the order [Br -] < [Cl -] < [I -] < [BF4 -] < [PF6 -] < [OTf -] < [NTf2 -]. Other than that, [Bmim][Br] could promote a greater solubility of water. The ILs were used after removing dissolved gases under a vacuum and heating. The saturated masses of water absorbed by each IL were tested under room temperature and atmospheric pressure in an open flask. The flasks contained different ILs (10 g) that were put in a humid condition (RH = 90%). In addition, the weights of the flasks were recorded each week until the weights remained constant. The additional final weight of each flask is regarded as the maximum water absorbed by ILs. ILs show competitive water absorption performance, especially imidazolium-based ILs. The results were exhibited in Table Ⅱ-5.

  toluene absorbing. According to Bedia's study, toluene absorption capacity by ILs is determined by the structure of both cation and anion [211]. As shown in Figure Ⅱ-12, toluene absorption capacity is improved by ILs with long-chain imidazolium cations and tetra-substituted longchain phosphonium or ammonium cations. Anions with highly halogenated hydrophobic can enhance toluene absorption. Considering the physical properties of ILs, commercially available imidazolium-based ILs (1-butyl-3-methylimidazolium bis(trifluoromethylsulfony)imide [Bmim][NTf2] and [Bmim][PF6]) were selected as absorbents for the ILM to remove toluene.

Figure II- 12 .

 12 Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K)[START_REF] Bedia | Optimized ionic liquids for toluene absorption[END_REF]

  Figure Ⅲ-1(a) shown, the sensor response to 500 ppb of VOCs is 24% without humidity. When the introduction of 50% of RH,the sensor response reduced to 12%. This result demonstrated that metal oxide gas sensor response is vulnerable due to the presence of humidity. Therefore, a humidity removal filter was used to eliminate this influence on the sensor response. The IL filter was placed upstream of the sensor, and then the sensor was exposed to 500 ppb of VOCs for 4 minutes with 50% RH.In FigureⅢ-1(b), it is clearly showing that sensor response kept its performance even in the presence of 50% RH when IL-based filter was placed upstream. A new solution was proposed to protect metal oxide gas sensors from the influence of humidity. More importantly, this filter does not disturb the normal response of the gas sensor.

Figure III- 1 .

 1 Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter

Figure III- 2 .

 2 Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 )

  the absorption of water by the [Bmim]Br, [Bmim][PF6] and [3htdp]Cl was 0.142, 0.033 and 0.055 g-water g-IL -1 . Hence, based on our experimental data, the water absorption capacity of the ILs was as follows: [Bmim]Br > [Bmim][PF6] > [3htdp]Cl. Therefore, [Bmim]Br was selected and used to remove humidity in this study.

  Figure Ⅲ-3(a) shows levels of humidity outlet as a function of time. Absorbing capacities are almost similar under different inlet flow rates becausethe flow rate is affected the hydrodynamic gas channels. From the diffusion point of view, the driving force of water vapor removal is mainly determined by the differences in relative humidity partial pressure across the membrane[START_REF] Dahi | Supported ionic liquid membranes for water and volatile organic compounds separation: Sorption and permeation properties[END_REF][START_REF] Liang | Robust thin film composite PDMS/PAN hollow fiber membranes for water vapor removal from humid air and gases[END_REF][START_REF] Chen | An experimental study of membranes for capturing water vapor from flue gas[END_REF][START_REF] Wang | Vapor separation of methanol-dimethyl carbonate mixture on SAPO-34 zeolite membrane[END_REF] between the feed gas and the IL surface. An ILM under a higher flow rate is faster to reach its absorption saturation. Even the contact time decreases with a flow rate increase from 0.50 to 1.50 L•min -1 ; the mass of water vapor sieving through the membrane increases with a higher feed flow rates, as shown in FigureⅢ-3(b). For the same concentration, when the feed flow rate increased, the quantity of water feed increased, so the mass of water absorbed by the ILM was higher during the same time before saturation. Furthermore, to verify the absorption process, the inlet RH and pressure were modified based on a constant inlet flow rate and concentration of RH.

Figure III- 3 .

 3 Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm)

  , at the given feed flow rate, it can be clearly seen that the ILM under lower pressure is much faster to reach to its absorption saturation. Furthermore, before the absorption saturation, during the same time, higher pressure provides more water absorbed by ILM (Figure Ⅲ-4(b)). A higher driving force is provided by higher partial pressure which results in a stronger diffusion during the porous ceramic membrane, and more water vapor reaches the ionic liquid and completes the absorption process.

  Figure Ⅲ-4(c). By increasing the water vapor concentration inlet, a higher amount of water vapor reaches the ILM provides a higher concentration gradient, which increases the driving force of mass transfer, resulting in the increase of mass transfer flux. According to Figure Ⅲ-4(d), the mass of water absorbed with different feed concentrations of RH inlet are similar, while the total mass of water absorbed by the ILs was the same, even with different feed concentrations.

Figure III- 4 .

 4 Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM ([Bmim]Br, T = 32 ℃, pressure = 1.00 atm, flow rate = 0.50 L min -1 )

Figure III- 5 .

 5 Figure III-5. (a) The effect of temperature on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different temperatures ([Bmim]Br, RH% inlet = 35%, pressure = 1.00 atm, flow rate = 0.50 L min -1 )

  Figure Ⅲ-7(a), Membrane (b) was much faster to reach its absorption saturation than Membrane (a). When the level of humidity outlet was equaled to the inlet, for Membrane (a) it took 180 hours, while for membrane (b), it only needed 71 hours. This result demonstrates that the position of the gas channels can influence the separation performance of the ILM. Furthermore, based on the mass of water absorbed by the ILMs, Membrane (b) can obtain more water within a shorter time than Membrane (a), which suggests that the Membrane (b) can

Figure III- 6 .

 6 Figure III-6. The position of the gas channels (channels with IL are grey, channels without IL are white)

Figure III- 7 . 4 . 5

 745 Figure III-7. (a) The effect of the gas channel position on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with the different position of gas channels ([Bmim]Br, RH% inlet = 35%, pressure = 1.00 atm, temperature = 32 ℃, flow rate = 0.50 L min -1 )

Figure Ⅲ- 8

 8 (a)). As shown in Figure Ⅲ-8(b), results indicate that the water contents of ILs decreased with time under the dry airflow. After three times absorption and desorption, the capacity of under high temperature for long-time operation. This means that this process is simple and efficient.

Figure III- 8 .

 8 Figure III-8. (a) The schematic diagram of removing and regeneration processes. (b) Three-time recycling of the ILM ([Bmim]Br, RH% inlet = 35%, remove humidity (green) / RH% inlet = 0 regeneration (black), T = 32 ℃, pressure = 1.00 atm, flow rate = 0.50 L min -1 )

  absorbents for ILMs. The physicochemical properties of [Bmim][PF6] and [Bmim][NTf2] are shown in Table IV-1. The ceramic membrane contained [Bmim][PF6] and [Bmim][NTf2] as absorbent was carried out at a continuous process to test the abilities of toluene removal. The concentration of toluene inlet was constant to 70 ppm at 0.30 L min -1 flow rate with 1.07 atm and 20 ℃.Figure IV-1 showed the concentration of toluene outlet of ILM as a function of time, and the quantity of toluene absorbed by ILM. From Figure IV-1(a), the concentration of toluene outlet of ILM exhibited lower than initial concentration. This result demonstrated that ILM could absorb toluene. Moreover, during the same absorption time and before ILM saturation, ILM with [Bmim][NTf2] showed better absorption ability on toluene than ILM with [Bmim][PF6] because the concentration of toluene outlet was much lower. Combination of the amount of toluene absorbed by ILMs (Figure IV-1(b)), during the same time and with same operating conditions, ILM with [Bmim][NTf2] absorbed toluene was 1.5 times higher than [Bmim][PF6] absorbed

1 .Figure

 1 Figure IV-1. (a) Effects of different ILs filled into ILM; (b) Mass of toluene absorbed by ILM with different ILs as absorbents. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.30 L min -1 , P = 1.07 atm, T = 20 ℃)

Figure IV- 2

 2 Figure IV-2 showed the effects of the initial concentration of toluene on the absorption capacity at 1.07 atm, 20 ℃ and flow rate of 0.30 L min -1 . The absorption capacity of ILM increase was observed with increasing the toluene concentration inlet. According to Figure IV-2(a), the absorption process can be divided into two stages. First, toluene passes through the porous support membrane very fast. This stage is shown at the beginning, the concentration of toluene outlet of ILM increasing rapidly. Second, the absorption went to a slow stage. The effect of inlet concentration was observed clearly during this stage. At the experiment stop time, the ILM at 50 ppm of toluene almost reached saturation, whereas the same ILM at 70 ppm did not

  When temperature and pressure were constant, the absorption capacity of toluene should be the same for the same quantity of [Bmim][NTf2]. From Figure IV-2(b), it is clearly that mass of toluene absorbed by ILM under 50 ppm of toluene inlet was much lower than ILM under 70 ppm. ILM under 50 ppm of toluene stop absorbing toluene during the experiment time.

Figure IV- 2 .

 2 Figure IV-2. (a) Effects of inlet toluene concentration on ILM absorption performance; (b) Mass of toluene absorbed by ILM with different inlet toluene concentrations. ([Bmim][NTf2], The concentration of toluene inlet = 50 / 70 ppm, Flow rate = 0.30 L min -1 , P = 1.07 atm, T = 20 ℃)

  15 and 0.30 L min -1 was studied. The flow rate of gas flow passing ILM was measured by a digital flowmeter in input and output of ILM. From Figure IV-3(a), there was a distinct downtrend for the concentration of toluene outlet with the acceleration of flow rate. This result demonstrated that absorptivity significantly influenced by the contact time between toluene and the IL. At high flow rate, toluene might be blown out without fully contacting with the IL. From the total mass of toluene absorbed by ILM as a function of time (Figure IV-3(b)), it was observed that ILM captured same mass of toluene with 0.10 and 0.15 L min -1 flow rate. In addition, at the experiment stop time, ILM with lower flow rate took three times than ILM with high flow rate. The higher flow rate could enhance the toluene absorption rate because of the higher quantity of toluene inlet during the same time.

Figure IV- 3 .

 3 Figure IV-3. (a) Effects of different flow rates on ILM absorption performance; (b) Mass of toluene absorbed by ILM with different flow rates; (c) Absorption rate of ILM at each time with different flow rates. ([Bmim][NTf2], The concentration of toluene inlet = 70 ppm, Flow rate =0.10 / 015/ 0.30 L min -1 , P = 1.07 atm, T = 20 ℃)

Figure IV- 4 .

 4 Figure IV-4. (a) Effects of different pressures on ILM absorption performance; (b) Mass of toluene absorbed by ILM with different pressures. ([Bmim][NTf2], the concentration of toluene inlet = 70 ppm, Flow rate = 0.30 L min -1 , P = 1.07 / 1.12 / 1.17 atm, T = 20 ℃)

  Figure IV-5(a), there was no significant effect of temperature on toluene removal by ILM in our testing range. However, from Figure IV-5(b), the amount of toluene absorbed by ILM increased with decreasing

Figure IV- 5 . 4 .

 54 Figure IV-5. (a) Effects of different temperatures on ILM absorption performance; (b) Mass of toluene absorbed by ILM with different temperatures. ([Bmim][NTf2], The concentration of toluene inlet = 70 ppm, Flow rate = 0.30 L min -1 , P = 1.07 atm, T = 20 / 40 / 60 ℃)

  atm and temperature = 20 ℃. From Figure IV-6(a), the concentration of toluene outlet of the ILM increased with time going. Around 32 hours, the concentration of toluene outlet was stable at the range from 63 to 64 ppm. Considering the accuracy of the VOCs sensor (± 10%), the ILM could be regarded at saturation. In addition, as Figure IV-6(b) shown, the mass of toluene absorbed increased by 0.22 mg-toluene g-IL -1 from 31 to 32 hour (1 hour). While this value only increased by 0.04 mg-toluene g-IL -1 from 32 to 33 hour (1 hour). And from 33 to 64 hour (31 hours), the mass of toluene absorbed by the ILM was 0.05 mg-toluene g-IL -1 . These results also demonstrated the ILM took 32 hours to reach saturation at proposed operating conditions, and the toluene absorption capacity of the ILM is 0.224 g-toluene g-IL -1 .

Figure IV- 6 .

 6 Figure IV-6. (a) Absorption of toluene at proposed operating conditions; (b) Mass of toluene absorbed by ILM at proposed operating conditions. ([Bmim][NTf2], The length of support membrane = 0.25 m, The concentration of toluene inlet = 70 ppm, Flow rate = 0.10 L min -1 , P = 1.17 atm, T = 20 ℃)

Figure IV- 7 .

 7 Figure IV-7. Toluene absorption capacities of different ILs at 20 ℃ and atmospheric pressure (toluene partial pressure was 0.02 atm for absorption). (a) ILs with [NTf2] anion; (b) other ILs [211]

   shown, the less quantity of toluene absorbed by the long membrane compared to the shorter one before 3.5 hours. The absorbed mass of long membrane increased linearly. While the short membrane grew faster and then slower in absorbed mass because mass transfer decrease with the concentration gradient decreasing. At the beginning of the experiment, for industrial length ILM, only the inlet part of the ILM is involved into the absorption process at the beginning of absorption process, while for the outlet part the ILM did not start absorbing because of the decreasing toluene concentration gradient. The concentration gradient between the gas phase and liquid phase provided a driving force for absorption. The toluene concentration in the gas phase dropped with membrane length, resulted in a reduction of mass transfer driving force and efficiency[START_REF] Tantikhajorngosol | A modeling study of module arrangement and experimental investigation of single stage module for physical absorption of biogas using hollow fiber membrane contactors[END_REF][START_REF] Dai | Modelling of a tubular membrane contactor for precombustion CO2 capture using ionic liquids: Influence of the membrane configuration, absorbent properties and operation parameters[END_REF][START_REF] Boributh | A modeling study on the effects of membrane characteristics and operating parameters on physical absorption of CO2 by hollow fiber membrane contactor[END_REF]. This figure only compared 5 hours of absorption because the absorption process of the short membrane was a relatively short duration compared to the long one. From Figure IV-8(c), the industrial length ILM was still on absorption at this experimental stop (around 160 hours) due to a clear tendency to stabilize the mass of toluene absorbed.

Figure IV- 8 .

 8 Figure IV-8. (a) Industrial length of support membrane on ILM absorption performance (Length = 1.178 m); (b) Mass of toluene absorbed by different lengths of ILM (within 5 hours of absorption); (c) Mass of toluene absorbed by ILM with a long support membrane. ([Bmim][NTf2], The length of support membrane = 0.25 / 1.178 m, The concentration of toluene inlet = 70 ppm, Flow rate = 0.10 L min -1 , P = 1.00 atm, T = 20 ℃ / Room temperature)

  Figure IV-9(a) exhibits the industrial ILM treated the different inlet concentrations of toluene, i.e. the inlet concentrations were selected based on the stabilized values: for an inlet concentration of 70 ppm, an outlet concentration of 50 ppm is stabilized during a long time: an inlet concentration of 50 ppm was tested for another experiment. Each absorption process lasted between 160 and 200 hours, and the ILMs did not reach saturation. The desorption process is simply blowing out the physically absorbed toluene with clean air, and other operating condition kept constant with the absorption process. It is noteworthy that the four experiments were performed consecutively, which means that an ILM operated continuously for more than 1 000 hours including the absorption and desorption processes (Figure IV-9(b). Each absorption and desorption are regarded as a complete treatment of toluene. No additional treatment of the ILM is performed between each completed process. Combined with Figure IV-9(c), the mass of toluene absorbed by the industrial ILM was still

  Figure IV-9(d) details an industrial treatment of an effluent containing. 70 ppm of toluene was continuously passed through three industrial membrane modules during 120 h. This duration is the maximum value of the stabilized outlet concentration for the three experiments. Each module contains only one ILM. The concentration of toluene decreased from 70 to 50 ppm after passing the first module. For the second module connected in series, the inlet concentration become 50 ppm toluene. After the gas passes through the second module, the concentration was dropped again to 25 ppm, which is considered the inlet concentration for the third module. The final experimental results show that 70 ppm toluene was reduced to 12 ppm after passing through three successive ILMs of the same industrial length. For practical industrial applications, the modules mentioned above may be multiple ILMs connected in series or in parallel to treat more flow rates. Furthermore, different modules also can contain different ILMs to achieve stepwise removal of different gases. This experiment is instructive for realizing the industrial application of ionic liquid membranes.

Figure IV- 9 .

 9 Figure IV-9. (a) Compared the industrial length of support membrane with the different concentration of toluene inlet on ILM absorption performance; (b) Arranged in series of the large membrane with the different concentration of toluene inlet as a function of time; (c) Mass of toluene absorbed by ILM with a long support membrane; (d) Scheme of the industrial length membranes arrange in series. ([Bmim][NTf2], Length of support membrane = 1.178 m, The concentration of toluene inlet = 70 / 50 / 25 ppm, Flow rate = 0.10 L min -1 , P = 1.00 atm, Room temperature)

Figure V- 1 .

 1 Figure V-1. Mass transfer coefficients in gas and IL bulk[START_REF] Harris | Temperature and Pressure Dependence of the Viscosity of the Ionic Liquid 1-Butyl-3-methylimidazolium Hexafluorophosphate[END_REF]

Figure V- 2 .

 2 Figure V-2. Proposed two steps sorption mechanisms for water sorption by the ILM [205]

Figure V- 3 .

 3 Figure V-3. The elevation view of one ILM channel (Green: the channel with the selected IL; Grey: the channel without ILs)

1 .

 1 Figure V-4. A comparison between experimental data and simulation fit by two steps model with different RH inlet. The insert figure shows the Langmuir model (step 1) results. ([Bmim]Br = 49.0 g, pressure = 1.00 atm, temperature = 32 ℃, flow rate = 0.50 L min -1)

Figure V- 5 .

 5 Figure V-5. A comparison between experimental data and simulation fit by1D diffusion model with different pressures. ([Bmim]Br = 49.0 g, RH% inlet = 35%, temperature = 32 ℃, flow rate = 0.50 L min -1 )

  Figure V-6. A comparison between experimental data and simulation fit by1D diffusion model with different flow rates. ([Bmim]Br= 49.0 g, RH% inlet = 35%, temperature = 32 ℃, pressure = 1.00 atm)

7 .Figure V- 7 .

 77 Figure V-7. A comparison between experimental data and simulation fit by 1D diffusion model with different temperatures. ([Bmim]Br = 49.0 g, RH% inlet = 35%, flow rate = 0.50 L min -1 , pressure = 1.00 atm)

Figure V- 9 .

 9 Figure V-9. A comparison between experimental data and simulation fit by 1D model with different concentrations inlet. ([Bmim][NTf2] = 42.4 g, pressure = 1.07 atm, temperature = 20 ℃, flow rate = 0.30 L min -1 )

  Figure V-10 gave the tendency of toluene gas diffusion into [Bmim][NTf2]

  -12 obtained from 1D diffusion model (step 2) based on this tendency. When the pressure increased 0.10 atm, the absorption capacity increased around 7% with the same diffusion coefficient. Higher pressure pushed more quantity of toluene into the IL bulk, which reduced the step 2 duration. It should mention that the absorption capacity increased due to higher pressure of gas phase should not regard as the real solubility of toluene into [Bmim][NTf2] because the parts of dissolved toluene will be released when pressure decreased.

Figure V- 10

 10 Figure V-10. A comparison between experimental data and simulation fit by 1D model with different pressure. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, temperature = 20 ℃, flow rate = 0.30 L min -1 )

13 .

 13 It observed that surface sorption rate was enhanced with a higher gas flow rate because the influences of the quantity of toluene inlet have a dominant role compared to contact time reduction. Therefore, the time consumption of surface adsorption was greatly reduced. As Figure V-11 and Table V-14 shown, the toluene concentration outlet was increased with a larger gas flow rate inlet due to shorter residual time on the porous membrane. The toluene flux across the membrane was also increased with larger gas flow rate.

Figure V- 11

 11 Figure V-11. A comparison between experimental data and simulation fit by 1D model with different flow rates. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, temperature = 20 ℃, pressure = 1.07 atm)

Figure V- 12

 12 Figure V-12. A comparison between experimental data and simulation fit by 1D model with different temperatures. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, pressure = 1.07 atm, flow rate = 0.30 L min -1 )

  atm and 20 ℃ because this value was depended on temperature and pressure. At proposed operating conditions, the ILM needed 31.47 hours to reach its saturation, and the saturated mass of toluene captured by the ILM was around 0.224 g-toluene g-IL -1 of [Bmim][NTf2].

Figure V- 13 .

 13 Figure V-13. Mass of toluene absorbed by the ILM at proposed operating conditions including experimental and simulated results. The insert figure shows the Langmuir model (step 1) results. ([Bmim][NTf2] = 42.4 g, The concentration of toluene inlet = 70 ppm, Flow rate = 0.10 L min -1 , P = 1.17 atm, T = 20 ℃)

  [START_REF] Qian | Carbon quantum dots decorated Bi2WO6 nanocomposite with enhanced photocatalytic oxidation activity for VOCs[END_REF]. During this experiment, the data was collected each second until the ILM saturation. The whole absorption experiment took around 71 hours to ensure the ILM saturation, and it was showed that the ILM reached saturation at 32 hours. The different numbers of experimental data were used to simulate the final saturated concentration (Cs) based on the same diffusion coefficient (D). The results were shown in Table V-18 (0.224 g g -1 of [Bmim][NTf2], in agreement with Bedia's result, is the value used as a reference. According to the simulated results, the calculated Cs was decreased with numbers of experimental data used decreasing. Generally, the Cs was underestimated when the experimental data was not enough. At the above parts, when the operating parameters were discussed according to this 1D model, almost all the final saturated concentration was underestimated because experimental time was not enough to reach the ILM saturation.

  time operation and high absorption capacity of ILs. The physical absorption of ILs provides simple desorption. It is expected to overcome the traditional contacting devices due to its nondispersive gas-liquid contact. The extremely high interfacial area and the modular structure can reduce equipment size and provides process intensification. ILMs can operate nearly at atmospheric pressure because the driving force of mass transfer is provided by a concentration gradient rather than pressure difference, which allows energy conservation. The hydrophobic surface coating of the ceramic membrane to protect the ILMs from wetting and suspended matters by low pore size used. Some advantages and applications have been achieved and studied by experimental and modeling methods in this study. The ILM was developed by a simple and handle method. Different processes with different separate tasks were proposed and discussed. The design and analysis of the blank experiments were investigated. The influence of process components and operating conditions including temperature, pressure and gas flow rate on the sensor response was eliminated: results are shown in Appendix 2. The separation of this ILM mainly based on the high affinity between the target gas or liquid pollutants and the selected IL. Therefore, the IL selection is the key factor for separation. From our experimental results and previous studies, most of ILs have been researched as absorbents. The results indicated that both cationic and anionic structures of ILs are affected absorption ability. The selection ranges of ILs are focused on a set of commercially available imidazolium-based ILs. Selection ILs for humidity removal. For humidity removal, ILs were selected to test mainly based on their hydrophilic-hydrophobic behaviors and viscosity properties at room temperature. Solubilities of IL are primarily defined by the anion followed by the cation alkyl side chain length. For cations, short and mono-branched alkyl chain is recommended for increasing the miscibility of ILs with water. For anions, the hydrophilicity of the anions for imidazolium-based ILs increases in the order [Br -] > [Cl -] > [I -] > [BF4 -] > [PF6

  that the gas absorption by the ILM could be divided into surface adsorption (step 1) and diffusion (step 2). The proposed model was good fitting on different operating parameters. For humidity removal, based on proposed optimized conditions (RH inlet = 45%, gas flow rate = 0.10 L min -1 , pressure = 1.20 atm, temperature = 25 ℃), the humidity saturation capacity of the ILM was 0.142 g-water g-IL -1 using [Bmim]Br as an absorbent. For toluene absorption, the toluene absorption capacity of the ILM was 0.224 g-toluene g-IL -1 of [Bmim][NTf2] with the optimized operational conditions based on our experiments (concentration of toluene inlet = 70 ppm, gas flow rate = 0.10 L min -1 , pressure = 1.17 atm, temperature = 20 ℃). As far as we know, the adsorption capacity of the ILM for toluene reaches the maximum capacity of the [Bmim][NTf2], which in agreement with the state-of-the-art result. Based on the experimental results, the effects of different parameters on the 1D diffusion model results were discussed.

Figure A2- 4 .

 4 Figure A2-4. Sensor response on different concentrations of toluene with different pressures (flow rate = 1.0 L min -1 , temperature = 32 ℃)

Figure I- 1 .

 1 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure I- 5 .

 5 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure I- 6 .

 6 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure I- 7 .

 7 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure I- 8 .

 8 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure II- 1 .

 1 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure II- 2 .

 2 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure II- 3 .

 3 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure II- 4 .

 4 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure II- 5 .

 5 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure II- 12 . 66 Figure IV- 4 . 85 Figure V- 5 .

 12664855 Figure I-1. Main VOCs removing and CO2 separation processes ................................................................... Figure I-2. The treatment of concentration and flow rate ranges of separation processes [Traitement d'air charge en COV hydrophobes par un procé dé hybride: absorption -pervaporation, Frederic Heymes 1 1 LGEI -Laboratoire de Gé nie de l'Environnement Industriel (2008)] .................................................. Figure I-3. Schematic drawing of a porous and a nonporous membrane and the transfer of solute across the membranes [56] ..................................................................................................................................... Figure I-4. Common organic cations of ILs ..................................................................................................Figure I-5. Schematic of SILMs [119] ..........................................................................................................Figure I-6. Schematic of polymer membranes and ILPMs [132] ..................................................................Figure I-7. Schematic of ILMMMs selective separation of toluene [146] .................................................... Figure I-8. Hollow fiber supported ILMs by Zhang et al. [172] ................................................................... Figure II-1. Photos of the combination of an ionic liquid and a ceramic membrane (ILM) ......................... Figure II-2. The schematic diagram of the test bench ................................................................................... Figure II-3. The schematic diagram of the gas and humidity generation system .......................................... Figure II-4. The schematic diagram of the humidity removal process ..........................................................Figure II-5. Different processes of blank experiments with the same operating conditions. (a) carter; (b) carter with ceramic membrane .............................................................................................................. Figure II-6. Some channels were closed at one end of a ceramic membrane. (a) channels were closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ......................................... Figure II-7. Sensor responses for a ceramic membrane with some channels closed. (a) channels are closed at gas enter end; (b) channels were closed at the gas outlet end. (Concentration of toluene inlet = 70 ppm, Flow rate = 0.3 L min -1 , Pressure = 1.00 / 1.07 atm, Temperature = 20 ℃) ................................ Figure II-8. The schematic diagram of VOCs removal process .................................................................... Figure II-9. (a) The photo of humidity sensor; (b) Typical output voltage vs relative humidity at 25 °C and V (voltage supply) ................................................................................................................................. Figure II-10. The different measure ranges of VOCs sensor ......................................................................... Figure II-11. VOCs sensor calibration for toluene ........................................................................................ Figure II-12. Map of predicted Henry's law constants for toluene. (102 MPa, T=298 K) [211]................... Figure III-1. (a) The sensor response to 500 ppb of VOCs with and without 50% RH; (b) comparison of sensor response to 500 ppb of VOCs under 50% RH with and without IL filter .................................. Figure III-2. (a) The effect of ionic liquids filled into an ILM on its humidity separation performance. (b) the mass of water absorbed by an ILM with different ionic liquids. (RH% inlet = 35%, T = 32 ℃, Pressure = 1.00 atm and flow rate = 0.50 L min -1 ) ............................................................................... Figure III-3. (a) The effect of flow rate on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM with different flow rates. ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, pressure = 1.00 atm) .............................................................................................................................. Figure III-4. (a) The effect of system pressure on the humidity separation performance of the ILM. (b) The mass of water absorbed by the ILM under different system pressures ([Bmim]Br, RH% inlet = 35%, T = 32 ℃, flow rate = 0.50 L min -1 ). (c) The effect of feed concentrations of relative humidity on the humidity separation performance of the ILM. (d) The mass of water vapor absorbed by the ILM

Figure V- 9 .

 9 Figure V-5. A comparison between experimental data and simulation fit by1D diffusion model with different pressures. ([Bmim]Br = 49.0 g, RH% inlet = 35%, temperature = 32 ℃, flow rate = 0.50 L min -1) ..................................................................................................................................................... Figure V-6. A comparison between experimental data and simulation fit by1D diffusion model with different flow rates. ([Bmim]Br= 49.0 g, RH% inlet = 35%, temperature = 32 ℃, pressure = 1.00 atm) ...............................................................................................................................................................Figure V-7. A comparison between experimental data and simulation fit by 1D diffusion model with different temperatures. ([Bmim]Br = 49.0 g, RH% inlet = 35%, flow rate = 0.50 L min -1 , pressure = 1.00 atm) ............................................................................................................................................... Figure V-8. Viscosity of pure [Bmim]Br as a function of temperature [309] ................................................ Figure V-9. A comparison between experimental data and simulation fit by 1D model with different concentrations inlet. ([Bmim][NTf2] = 42.4 g, pressure = 1.07 atm, temperature = 20 ℃, flow rate = 0.30 L min -1 ) .......................................................................................................................................... Figure V-10. A comparison between experimental data and simulation fit by 1D model with different pressure. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, temperature = 20 ℃, flow rate = 0.30 L min -1 ) ..................................................................................................................................................... Figure V-11. A comparison between experimental data and simulation fit by 1D model with different flow rates. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, temperature = 20 ℃, pressure = 1.07 atm) .. Figure V-12. A comparison between experimental data and simulation fit by 1D model with different temperatures. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, pressure = 1.07 atm, flow rate = 0.30 L min -1 ) .................................................................................................................................................. Figure V-13. Mass of toluene absorbed by the ILM at proposed operating conditions including experimental and simulated results. The insert figure shows the Langmuir model (step 1) results. ([Bmim][NTf2] = 42.4 g, The concentration of toluene inlet = 70 ppm, Flow rate = 0.10 L min -1 , P = 1.17 atm, T = 20 ℃) ....................................................................................................................................................

Figure V- 12

 12 Figure V-5. A comparison between experimental data and simulation fit by1D diffusion model with different pressures. ([Bmim]Br = 49.0 g, RH% inlet = 35%, temperature = 32 ℃, flow rate = 0.50 L min -1) ..................................................................................................................................................... Figure V-6. A comparison between experimental data and simulation fit by1D diffusion model with different flow rates. ([Bmim]Br= 49.0 g, RH% inlet = 35%, temperature = 32 ℃, pressure = 1.00 atm) ...............................................................................................................................................................Figure V-7. A comparison between experimental data and simulation fit by 1D diffusion model with different temperatures. ([Bmim]Br = 49.0 g, RH% inlet = 35%, flow rate = 0.50 L min -1 , pressure = 1.00 atm) ............................................................................................................................................... Figure V-8. Viscosity of pure [Bmim]Br as a function of temperature [309] ................................................ Figure V-9. A comparison between experimental data and simulation fit by 1D model with different concentrations inlet. ([Bmim][NTf2] = 42.4 g, pressure = 1.07 atm, temperature = 20 ℃, flow rate = 0.30 L min -1 ) .......................................................................................................................................... Figure V-10. A comparison between experimental data and simulation fit by 1D model with different pressure. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, temperature = 20 ℃, flow rate = 0.30 L min -1 ) ..................................................................................................................................................... Figure V-11. A comparison between experimental data and simulation fit by 1D model with different flow rates. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, temperature = 20 ℃, pressure = 1.07 atm) .. Figure V-12. A comparison between experimental data and simulation fit by 1D model with different temperatures. ([Bmim][NTf2] = 42.4 g, concentration = 70 ppm, pressure = 1.07 atm, flow rate = 0.30 L min -1 ) .................................................................................................................................................. Figure V-13. Mass of toluene absorbed by the ILM at proposed operating conditions including experimental and simulated results. The insert figure shows the Langmuir model (step 1) results. ([Bmim][NTf2] = 42.4 g, The concentration of toluene inlet = 70 ppm, Flow rate = 0.10 L min -1 , P = 1.17 atm, T = 20 ℃) ....................................................................................................................................................

Table Ⅰ

 Ⅰ

-2 exhibits the main difference of features between RTILs and other traditional solvents.

Table I -

 I 2. Comparison of RTILs and traditional organic solvents[START_REF] Egorova | Fundamental importance of ionic interactions in the liquid phase: A review of recent studies of ionic liquids in biomedical and pharmaceutical applications[END_REF][START_REF] Marsh | Room temperature ionic liquids and their mixtures-a review[END_REF]

	Features	RTILs	Traditional solvents
	Applicability	Multifunctional	Single functional
	Chirality	Tunable	Rare
	Vapor pressure	Negligible	Follow C-Clapeyron equation
	Flammability	Non-flammable	Flammable
	Solvation	Strongly solvating	Weakly solvating
	Polarity	Polarity depends	Conventional polarity
	Tuneability	Designer solvents	Limited range
	Recyclability	Economic imperative	Green imperative
	Viscosity (cP)	22-40 000	0.2-100
	Density (g.cm -3 )	0.8-3.3	1.3-1.6

Table I -

 I 3. Common anions of ILs

	Organic anions	Mineral anions

Table I -

 I

	X -	r (Å)	Na + X -	Melting point (K)	Emim + X -
	Cl -	1.7	1074		360
	PF6 -	2.4	> 473		333
	AlCl4 -	2.8	458		279
	Alkyl

4. Effects of ILs characterizes on their properties

Effects of the cation/anion asymmetry on the melting point

length effects on the melting point of the bromide salts

		Cations		Melting point (K)
		[NMe4] +		> 573
		[Net4] +		557
		[NBu4] +		399
	[NHex4] +		373
	[NOct4] +		368
		Physicochemical values of some ILs
	ILs	M (g mol -1 )	T (K)	Density (g cm 3 )	Viscosity (cP)
	[Bmim][BF4]	226	193	1.12	233
	[Bmim][AlCl4]	321	-	1.33	19
	[Bmim][NTf2]	419	267	1.44	69
	[Bmim][PF6]	284	265	1.37	257
	[Bmim][OP(O) (OBu)2]	348	-	1.04	1896
	[Mmim][OP(OMe)2]	222	-	1.26

Table II -

 II 2. PID sensor responses on carter connecting with different parameters

	Devices	Ctoluene inlet (ppm)	Time (min)	Sensor response (ppm)	Flow rate set (L min -1 )	Real flow rate (L min -1 )	Pset (atm)	Preal (atm)
	Carter	0 70 0 70	2	1.44 70.71 1.31 71.38	0.3	0.318-0.321 0.319-0.323 0.305 0.307	1.00 1.07	0.97-1.03 0.97-1.03 1.07 1.07

Table II -

 II

3. Different parameters for a ceramic membrane with some channels closed. ((a) channels are closed at gas inlet end; (b) channels are closed at gas outlet end) Figure

IV-2 Ctoluene inlet (ppm) Time (min) Sensor response (ppm) Flow rate set (L min -1 ) Real flow rate (L min -1 ) Pset (atm) Preal (atm)

	(a) (b) (a) (b)	0 70 0 70 0 70 0 70	5	2.28 66.98 3.51 69.26 2.24 67.26 2.61 72.17	0.3	0.324 0.324 0.322 0.301-0.324 0.307 0.309 0.305 0.305	1.00 1.07	1.00 1.01 1.00 1.00 1.07 1.07 1.07 1.07

Table II -

 II 4. Operating parameters for gas removal processes

	Operating parameters	Ranges
		0.50
	Humidity	1.00
	Flow rate	1.50
	(L min -1 )	0.10
	VOCs	0.15
		0.30
		1.00
	Humidity	1.10
	Pressure	1.20
	(atm)	1.07
	VOCs	1.12
		1.17

Table II -

 II 5. Chemical structures of the ionic liquids (ILs) used

	Contents	[Bmim]Br	[Bmim][PF6]	[3htdp]Cl
	Name	1-butyl-3-methylimidazolium Bromide	1-butyl-3-methylimidazolium Hexafluorophosphate	Trihexyl(tetradecyl)phosp honium Chloride
	Chemical structure
	Molar mass (g• mol -1 )	219.13	284.19	519.32
	Water affinity	hydrophilic	hydrophobic	hydrophobic
	Mass of IL used (g)	49.0	53.4	34.1
	Mass of water
	absorbed by per gram	0.142	0.033	0.055
	of IL (g)

Table III -

 III 1. Summary on the position of the gas channels

	Contents	Membrane (a)	Membrane (b)
	Total channels	19
	Channels with IL	13
	Channels without IL	6
	Mass of IL (g)	38.7	38.4
	Total mass of water absorbed by ILM (g)	2.95	2.85

Table III -

 III 2. Summary of the mass of water absorbed by the same ILM under different operating conditions

	Operating Conditions		Mass of Water Absorbed (g)	y* (%)
		0.50	0.42	0.86
	Flow rate (L min -1 )	1.00	0.65	1.33
		1.50	1.22	2.59
		1.00	0.42	0.86
	Pressure (atm)	1.10	0.53	1.08
		1.20	2.33	4.76
	Feed concentration	35	2.34	4.78
	(%)	50	2.33	4.76
		25	2.00	4.08
	Temperature (℃)	32	0.41	0.84
		39	0.43	0.88

* 𝑦 = 𝑚 𝑡ℎ𝑒 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝐼𝐿𝑀 𝑚 𝑡ℎ𝑒 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑡ℎ𝑒 𝐼𝐿 𝑢𝑠𝑒𝑑 × 100%

  -1, the simulated results of surface sorption showed that the RH of 35% inlet needed around 40 minutes (t0 = 40 mins) to reach the surface sorption equilibrium. While the RH 45% inlet only took 25 minutes. However, a different phenomenon was observed in step 2. Figure V-4 shows that the mass of water absorbed by [Bmim]Br increases with an increasing RH inlet (1D diffusion model, step 2). The ILM reached its sorption saturation about 33 hours with RH 45% inlet, while during the same time, the RH outlet value was only 91% of the RH 35% inlet. It means the ILM with RH 35% inlet did not reach its sorption saturation during the experimental time.Table V-2

Table V -

 V

	RH inlet (%)	msaturation (g-water g-IL -1 )	Dwater-IL (m 2 s -1 )	R 2
	35	0.121	4.16*10 -9	0.993
	45	0.129		0.999

2. 1D diffusion model parameters of different RH inlet

Table V -

 V 6. 1D diffusion model parameters of different feed flow rates

	Flow rate (L min -1 )	msaturation (g-water g-IL -1 )	Dwater-IL (m 2 s -1 )	R 2
	0.50	0.121	4.16*10 -9	0.977
	1.00	0.141	4.32*10 -9	0.996
	1.50	0.139	4.32*10 -9	0.991

Table V -

 V 9. The surface sorption parameters of different concentrations inlet

	Concentration (ppm)	Mass of toluene inlet (g min -1 )	kL	Qm (g-toluene g-IL -1 )	t (min)	R 2
	70	0.080*10 -3	0.0012	0.17*10 -3	2.33	0.990
	50	0.057*10 -3	0.0004	0.11*10 -3	4.50	0.992

Table V -

 V 10. ILM saturated with different concentrations inlet based on 1D model

	Concentration (ppm)	Time (h)	msaturation (g

-toluene g-IL -1 ) Dtoluene-IL (m 2 s -1 ) R 2

	70 50	27.78 30.56	0.119 0.037	4.12*10 -11	0.986 0.998

Table V -11. The surface sorption parameters of different pressures Pressure (atm) Mass of toluene inlet (g min -1 ) kL Qm (g-toluene g-IL -1 )

 V

					t (min)	R 2
	1.07	0.085*10 -3	0.0012	0.17*10 -3	2.33	0.990
	1.12	0.089*10 -3	0.0012	0.19*10 -3	2.63	0.989
	1.17	0.093*10 -3	0.0012	0.21*10 -3	2.92	0.990
	Table V-12. ILM saturated with different pressures based on the 1D diffusion model
	Pressure (atm)	Time (h)	msaturation (g-toluene g-IL -1 )	Dtoluene-IL (m 2 s -1 )	R 2
	1.07	30.46	0.129		4.12*10 -11	0.986
	1.12	29.09	0.174		4.32*10 -11	0.990
	1.17	28.28	0.219		4.42*10 -11	0.995

Table V -

 V [START_REF] Liu | Catalytic removal of volatile organic compounds using ordered porous transition metal oxide and supported noble metal catalysts[END_REF]. The surface sorption parameters of different flow rates

	Flow rate (L min -1 )	Mass of toluene inlet (g min -1 )	kL	Qm (g-toluene g-IL -1 )	t (min)	R 2
	0.10	0.028*10 -3	0.0003	0.15*10 -3	8.33	0.983
	0.15	0.042*10 -3	0.0004	0.14*10 -3	5.83	0.982
	0.30	0.085*10 -3	0.0012	0.17*10 -3	2.33	0.986

Table V -

 V [START_REF] Gallegos | Removal of VOCs by catalytic process. A study of MnZnO composites synthesized from waste alkaline and Zn/C batteries[END_REF]. ILM saturated with different flow rates based on the 1D model at given operating conditions

	Flow rate (L min -1 )	Time (h)	msaturation (g-toluene g-IL -1 )	Dtoluene-IL (m 2 s -1 )	R 2
	0.10	29.73	0.078	4.12*10 -11	0.992
	0.15	29.38	0.073	4.12*10 -11	0.996
	0.30	30.46	0.129	4.12*10 -11	0.986

Table V

 V

	-15. The viscosity of [Bmim][NTf2] with different temperatures [317]
	Temperature (℃)	Pressure (atm)	Viscosity (mPa s)
	20		62.0
	40	1.07	27.8
	60		15.1

Table V -

 V [START_REF] Piumetti | Mesoporous manganese oxides prepared by solution combustion synthesis as catalysts for the total oxidation of VOCs[END_REF]. The surface sorption parameters of different temperatures

	Temperature
	(℃)

Mass of toluene inlet (g min -1 ) kL Qm (g-toluene g-IL -1 )

					t (min)	R 2
	20	0.085*10 -3	0.0012	0.17*10 -3	2.33	0.990
	40	0.079*10 -3	0.0013	0.20*10 -3	2.50	0.995
	60	0.075*10 -3	0.0015	0.22*10 -3	2.45	0.991

Table V -

 V [START_REF] Ji | Mesoporous TiO2 under VUV irradiation: Enhanced photocatalytic oxidation for VOCs degradation at room temperature[END_REF]. ILM saturated with different temperatures based on the 1D model at given operating conditions

Temperature (℃) Time (h) msaturation (g-toluene g-IL -1 ) Dtoluene-IL (m 2 s -1 ) R 2

	20	30.46	0.129	4.12*10 -11	0.986
	40	11.03	0.071	1.10*10 -10	0.983
	60	7.36	0.053	1.63*10 -10	0.981

Table V -

 V [START_REF] Yang | Deep oxidation of chlorinated VOCs over CeO2-based transition metal mixed oxide catalysts[END_REF]. The effect of numbers of experimental data used on simulated results

	Numbers of experimental data used	Cs (g-toluene g-IL -1 )	D (m 2 s -1 )	Difference (%)
	255 600 (71.00 h -all data)	0.224		-
	120 000 (33.33 h)	0.224		0.00
	80 000 (22.22 h) 40 000 (11.11 h)	0.217 0.202	4.12*10 -11	3.13 9.82
	10 000 (2.78 h)	0.156		30.36
	6 000 (1.67 h)	0.134		40.18

  According to the water solubility of ILs and commercial availability, the high absorption capacity of [Bmim]Br for water vapor was 0.142 g-water g-IL -1 , which is much higher than the water absorption capacity of [Bmim][PF6] and [3hdpt]Cl. Therefore, [Bmim]Br was selected as an absorbent for humidity removal.The different operational conditions, including concentration inlet, flow rate, pressure and temperature, have been investigated. It is worth to mention that when the effects of one parameter were discussed, other operational parameters were kept constant.

	Selection ILs for toluene removal. For toluene removal, ILs were selected to test mainly
	based on toluene absorption capacities. For cations, long chain imidazolium cations can
	enhance toluene absorption. For anions, highly halogenated hydrophobic anions can improve
	toluene absorption. Toluene absorption capacity of [Bmim][NTf2] is 0.224 g-toluene g-IL -1 . In
	addition, [Bmim][NTf2] is commercially available. Compared to toluene absorption capacities
	of other available ILs, [Bmim][NTf2] was selected as an absorbent for toluene removal.

-] > [OTf -] > [NTf2 -].

Conclusions and Perspectives

wonderful atmosphere both diligent and relaxed.

Thanks to China Scholarship Council (CSC) who gave me the scholarship (N o

List of Tables

List of ILs

Abbreviations

List of Abbreviations Abstract

The elimination of pollutants from a gaseous or liquid mixture is a major challenge in terms of reducing the environmental impact of many industrial processes. The industrial application of supported liquid membranes based on conventional organic liquids is limited due to their instability and service life. Ionic liquids are promising alternative solvents in selective separation due to their negligible vapor pressure and their chemical-physical properties. In this study, a new hybrid process, the combination of ILs and a tubular ceramic membrane (ILM), was developed for the treatment of gases or liquids. Compared to conventional processes, ILM offers high stability and mechanical strength over a long operating period. In addition, the specific properties of ILs ensure selectivity and high absorption capacities. This concept is modular and adaptable to a wide range of industrial problems for the removal of harmful gases or liquids, the separation of biogases and the removal of moisture. In the case of gas treatment, the removal of moisture to protect the gas sensor and the treatment of industrial gas containing toluene are the two parts developed in this manuscript. The effects of several operating parameters, including gas flow rate, temperature, pressure, feed concentration, effective membrane area, were investigated on both moisture removal and toluene removal in the gas phase. A two-step model was used to model the experimental results and evaluate the LIM separation performance. Finally, tests with an industrial-scale ILM confirmed the small-scale results.

Keywords

Ionic liquid; Membrane process; Gas purification; Humidity removal; Modelisation Résumé L'élimination des polluants d'un mélange gazeux ou liquide est un enjeu majeur en termes de réduction de l'impact environnemental de nombreux procédés industriels. Les liquides ioniques sont des solvants de remplacement prometteurs dans la séparation sélective en raison de leur pression de vapeur négligeable et de leurs propriétés chimico-physiques. Dans cette étude, un nouveau procédé hybride, la combinaison des IL et d'une membrane céramique tubulaire (ILM), a été développé dans le but de traiter des gaz ou des liquides. Par rapport aux procédés conventionels, l'ILM offre une grande stabilité et une résistance mécanique élevée pendant une longue période de fonctionnement. De plus, les propriétés spécifiques des ILs assurent la sélectivité et de fortes capacités d'absorption. Dans le cas des traitements de gaz, l'élimination de l'humidité pour protéger le capteur de gaz et le traitement du gaz industriel contenant du toluène sont les deux parties développées dans ce manuscrit. Les effets de plusieurs paramètres de fonctionnement, notamment le débit de gaz, la température, la pression, la concentration d'alimentation, la surface effective de la membrane ont été étudiés à la fois sur l'élimination de l'humidité et du toluène en phase gaz. Un modèle mathématique en deux étapes a été utilisé pour modéliser les résultats expérimentaux et évaluer la performance de séparation des ILM. Enfin des essais avec un ILM de taille industrielle ont confortés les résultats à petite échelle.

Mots-clés

Liquide ionique; Procédé membranaire; Purifiaction des gaz; Élimination de l'humidité; Modélisation