Bo Han
email: han.bo@ntu.edu.sg

Sarah M Chevrier

Qingyu Yan

Jean-Christophe P Gabriel
email: jean-christophe.gabriel@cea.fr

Tailorable metal-organic framework based thin film nanocomposite membrane for lithium recovery from wasted batteries

Keywords: Lithium recovery, MIL-101 (Cr), Ionic liquid, TFN membrane, Nanofiltration

This paper presents a tailorable method for the preparation of hierarchically structured membranes for efficient lithium recovery. Firstly, a metal-organic framework (MOF), namely MIL-101 (Cr), is grafted with different ionic liquids (ILs) onto its coordinate unsaturated site (CUS). The modified MOF (IL-MOF) is then used as nanoparticles to fabricate the hydrophilic polyvinylidene fluoride (PVDF) based thin film nanocomposite (TFN) membrane. Secondly, comprehensive characterizations of both the nanoparticle and the IL-MOF based TFN membrane are carried out. Thirdly, lithium recovery is performed experimentally using simulated lithium-ion batteries (LIBs) leaching solution with the as-synthesized membrane.

The first order ageing test of TFN membrane is conducted by MOF detachment tendency investigation and ILs leaching tendency evaluation. The results show that IL-MOF nanoparticles have a significant effect on lithium recovery. Compared with the original membrane, the IL-MOF-TFN membrane exhibits a fourfold lithium selectivity enhancement for 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ (from 1.73 to 8.91), 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ (from 1.75 to 9.94) and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ (from 1.69 to 10.09), as well as improved regeneration behavior, permeability (up to 45.0 L/(m 2 •h•bar)) and antifouling performance (flux recovery rate FRR up to 96.39%). It is found that 98.9% of the lithium was recovered from the feed solution over five repeated filtration cycles with maintained membrane integrity. This work highlights the advances in the design, modification and integration of MOFs into mechanically and chemically stable membrane technology for lithium recovery.

Introduction

Lithium is a strategic metal that is key to many applications, such as glass, ceramics and polymer production, lubricants and battery technologies [START_REF] Harper | Recycling lithium-ion batteries from electric vehicles[END_REF]. The lithium market is already under pressure as lithium-ion batteries (LIBs) are the most widely used rechargeable batteries in many electronic products, such as portable computers, electric vehicles, and mobile phones. This market is further stressed by the centralization of production in only a few mines and the 6% annual increase in consumption reported over the last decade [START_REF] Li | Membrane-based technologies for lithium recovery from water lithium resources: A review[END_REF]. Over-consumption, price increases and improper disposal of lithium compounds are leading to lithium scarcity and environmental pollution [START_REF] Choi | The impact of anthropogenic inputs on lithium content in river and tap water[END_REF][START_REF] Turcheniuk | Ten years left to redesign lithium-ion batteries[END_REF], making it necessary to develop efficient recycling processes. In general, industrial lithium extraction is mainly achieved by lithium recovery from aqueous resources such as salt-lake brine and spent lithium-ion batteries (LIBs) leach liquor, due to its higher reserves and lower cost [START_REF] Li | Membrane-based technologies for lithium recovery from water lithium resources: A review[END_REF]. It should be noted that the conventional precipitation method is not applicable for lithium recovery when low amounts of lithium (in terms of mass ratio) are present in the feed solution [START_REF] Li | A positively charged composite nanofiltration membrane modified by EDTA for LiCl/MgCl2 separation[END_REF][START_REF] Ciez | Examining different recycling processes for lithium-ion batteries[END_REF]. Other Li recovery approaches such as lithium ion-sieve (LIS) [START_REF] Xu | Extraction of lithium with functionalized lithium ion-sieves[END_REF] and solvent extraction [START_REF] Lei | Solvent extraction for recycling of spent lithium-ion batteries[END_REF] result in large amounts of wastewater. In addition, LIS and solvent extraction require multiple steps such as adsorption/desorption and extraction/stripping, respectively. These shortcomings add to the complexity of lithium recovery. In the recent decades, many researchers have proved that membrane technology-based lithium recovery process such as ion-imprinted membrane [START_REF] Sun | Synthesis of ion imprinted nanocomposite membranes for selective adsorption of lithium[END_REF], supported liquid membrane [START_REF] Zante | Highly selective transport of lithium across a supported liquid membrane[END_REF], electrodialysis [START_REF] Song | Recovery of lithium from spent lithium-ion batteries using precipitation and electrodialysis techniques[END_REF] and membrane distillation crystallization [START_REF] Quist-Jensen | A study of membrane distillation and crystallization for lithium recovery from high-concentrated aqueous solutions[END_REF] is less energy intensive, environmentally friendly and does not change the state of lithium. Therefore, research on membrane technology for lithium recovery is of industrial and environmental importance. Among all the membranebased technologies, nanofiltration (NF) membrane has been widely used for the separation of low molecular weight organics and divalent ions from aqueous environments due to its relatively high selectivity [START_REF] Nativ | Separation of divalent and monovalent ions using flowelectrode capacitive deionization with nanofiltration membranes[END_REF]. It should be noted that NF is the only membrane technology for large-scale lithium recovery applications [START_REF] Li | Membrane-based technologies for lithium recovery from water lithium resources: A review[END_REF]. The main separation mechanisms of NF membranes are steric exclusion and electrostatic effect [START_REF] Zhu | MOF-positioned polyamide membranes with a fishnet-like structure for elevated nanofiltration performance[END_REF][START_REF] Feng | Recent advances of loose nanofiltration membranes for dye/salt separation[END_REF]. However, NF membranes have an unavoidable trade-off defect: a high solvent permeability is accompanied by a low solute selectivity and vice versa. The trade-off defect of NF membranes has hindered their further industrial and commercial development. In addition, problems such as non-selective interfacial voids, poor dispersion and nanoparticle aggregation are common, resulting in poor separation performance.

Recently, the use of the thin film composite (TFC) membrane has gradually increased [START_REF] Zhang | A review on polyester and polyester-amide thin film composite nanofiltration membranes: Synthesis, characteristics and applications[END_REF]. As an energy-efficient NF membrane [START_REF] Golpour | Preparation and characterization of new PA-MOF/PPSU-GO membrane for the separation of KHI from water[END_REF], the TFC membrane consists of a porous support substrate and a thin polyamide film (ultrathin selective layer) [START_REF] Ji | Polyamide membranes with net-like nanostructures induced by different charged mofs for elevated nanofiltration[END_REF][START_REF] Golpour | Development of a new nanofiltration membrane for removal of kinetic hydrate inhibitor from water[END_REF]. The typical configuration of TFC membranes could be subdivided into : 1) a top ultrathin skin polyamide (PA) layer which controls the separation performance; 2) a middle porous support layer which provides the necessary mechanical support and functions as a platform for IP process; and 3) a bottom nonwoven fabric layer which gives further mechanical support. The ultrathin selective layer is prepared by interfacial polymerization (IP) in situ on the surface of the porous support substrate. IP is a diffusion reaction process and mainly occurs between organic monomers (acyl chlorides) and aqueous diamine monomers, where the aromatic polyamide (PA) is formed at the oil-water interface as a result of polycondensation of acyl chlorides and diamines. The diffusion rate of IP can be well-controlled and highly permeable polyamide films is obtained by using advanced techniques such as low temperature reaction [START_REF] Liu | One-step constructed ultrathin Janus polyamide nanofilms with opposite charges for highly efficient nanofiltration[END_REF], macromolecule incorporation [START_REF] Tan | Polyamide membranes with nanoscale Turing structures for water purification[END_REF], nano-foaming [START_REF] Ma | Nanofoaming of polyamide desalination membranes to tune permeability and selectivity[END_REF] and electro-spraying [START_REF] Chowdhury | 3D printed polyamide membranes for desalination[END_REF]. Typically, polyamide films formed by IP should have either an ultrathin layer with reduced mass transfer resistance or a robust surface with abundant free transport sites [START_REF] Han | Ionic liquid modified COF nanosheet interlayered polyamide membranes for elevated nanofiltration performance[END_REF][START_REF] Xie | Fabrication of novel thinfilm nanocomposite polyamide membrane by the interlayer approach: A review[END_REF]. Both of these characteristics result in improved water permeability. As for the polymer substrate, polyvinylidene fluoride (PVDF) membrane is always an attractive choice due to its promising chemical stability, excellent compatibility and high mechanical strength. However, the lack of unsaturated functional groups on the surface results in poor separation performance [START_REF] Lu | Multilayered ion-imprinted membranes with high selectivity towards Li+ based on the synergistic effect of 12-crown-4 and polyether sulfone[END_REF]. In addition, the foremost problems with the TFC membrane is its interfacial defects and low retention/poor selectivity of multivalent salts [START_REF] Zhu | Elevated performance of thin film nanocomposite membranes enabled by modified hydrophilic MOFs for nanofiltration[END_REF]. One way to overcome these problems is to incorporate nanomaterials into TFC membranes to form thin film nanocomposite (TFN) membranes. The embedded nanofillers create additional channels for the transfer of target molecules through their inherent interfacial voids and nanopores within the PA layer. This unique structure gives TFN membranes both outstanding solvent permeability and excellent solute selectivity. To date, various nanomaterials such as graphene oxide (GO) [START_REF] Yin | Graphene oxide (GO) enhanced polyamide (PA) thin-film nanocomposite (TFN) membrane for water purification[END_REF], carbon nanotubes (CNTs) [START_REF] Son | Thin-film nanocomposite membrane with CNT positioning in support layer for energy harvesting from saline water[END_REF], zeolite [START_REF] Dong | A thin-film nanocomposite nanofiltration membrane prepared on a support with in situ embedded zeolite nanoparticles[END_REF] and nanoclay [START_REF] Bojnourd | Preparation and characterization of a nanoclay/PVA/PSf nanocomposite membrane for removal of pharmaceuticals from water[END_REF] have been employed for the preparation of TFN membrane.

Recently, metal-organic frameworks (MOFs) are attracting increasing attention as nanofillers.

MOFs are crystalline porous materials composed of metal ions (or clusters) and organic ligands.

Benefiting from the presence of organic ligands, MOFs show higher affinity/compatibility with polymer chains than inorganic porous nanomaterials such as zeolite [START_REF] Sorribas | High flux thin film nanocomposite membranes based on metal-organic frameworks for organic solvent nanofiltration[END_REF]. Consequently, high affinity/compatibility leads to controllable MOFs-polymer interfacial interactions, which has a favorable effect on the formation of relatively ideal interfacial cavities, while solute rejection is largely maintained [START_REF] Sorribas | High flux thin film nanocomposite membranes based on metal-organic frameworks for organic solvent nanofiltration[END_REF]. In addition, MOFs show superiority over other nanomaterials due to their versatile functional organic linkers, ordered porous cavities, high specific surface area and tailorable structures. The incorporation of porous MOFs with specific pore size could enhance the size exclusion effect of the TFN membrane, thus achieving high selectivity or rejection rate of metal ions [START_REF] Abdollahzadeh | Designing Angstrom-Scale Asymmetric MOF-on-MOF Cavities for High Monovalent Ion Selectivity[END_REF][START_REF] Xiao | A lithium ion selective membrane synthesized from a double layered Zrbased metalorganic framework (MOF-on-MOF) thin film[END_REF][START_REF] Zhao | Preparation and Lithium-Ion Separation Property of ZIF-8 Membrane with Excellent Flexibility[END_REF]. Besides that, additional water transfer pathways are usually created within the unique MOF channels, which brings favorable effect on the water permeance [START_REF] Park | Selective lithium and magnesium adsorption by phosphonate metal-organic framework-incorporated alginate hydrogel inspired from lithium adsorption characteristics of brown algae[END_REF][START_REF] Mohammad | Metal-Phenolic network and metal-organic framework composite membrane for lithium ion extraction[END_REF]. In addition, the use of hydrophilic MOFs on the TFN membrane would also improve the surface wettability, which also leads to the higher water permeability [START_REF] Raggam | Advances in metal organic framework (MOF)-Based membranes and adsorbents for lithiumion extraction[END_REF][START_REF] Liu | Application of Nanofiltration Membrane Based on Metal-Organic Frameworks (MOFs) in the Separation of Magnesium and Lithium from Salt Lakes[END_REF]. Therefore, the trade-off defect in NF membranes is addressed. Such phenomenon has also been reported in other works [START_REF] Ma | Thin-film nanocomposite (TFN) membranes incorporated with super-hydrophilic metal-organic framework (MOF) UiO-66: toward enhancement of water flux and salt rejection[END_REF][START_REF] Xiao | Improvement of thin-film nanocomposite (TFN) membrane performance by CAU-1 with low charge and small size[END_REF]. Among all the MOFs, a chromium terephthalate-based MOF, namely MIL-101 (Cr) [START_REF] Férey | A chromium terephthalate-based solid with unusually large pore volumes and surface area[END_REF], has been considered as a potential candidate for TFN membrane technology.

Structurally, MIL-101 (Cr) is a micro-mesoporous material with giant pore size (~ 30 to 34 Å), high pore volume (~ 702,000 Å 3 ) and large Langmuir surface area (~ 5900 ± 300 m 2 /g). In addition, MIL-101 (Cr) is chemically stable in aqueous environments due to the strong coordination bonds between carboxylate-type linkers and high-valence metal ions Cr 3+ [START_REF] Wang | Applications of water stable metal-organic frameworks[END_REF].

One of the main advantages of MIL-101 (Cr) is that it has two mesoporous cages with internal free diameters of ~ 29 Å and 34 Å, respectively. These large openings always result in high solution flux. In a study, Sorribas et al. [START_REF] Sorribas | High flux thin film nanocomposite membranes based on metal-organic frameworks for organic solvent nanofiltration[END_REF] used MIL-101 (Cr) based TFN membrane for organic solvent nanofiltration and an exceptional increase in permeance from 1.7 up to 11.1 L•m -2 •h -1 •bar -1 for tetrahydrofuran/styrene oligomer solution is observed. To date, although several works have reported the remarkable permeability of MIL-101 (Cr) based TFN membranes in organic solvent nanofiltration application, the study of MIL-101(Cr)-based TFN membranes used for metal ion separation has rarely been directly investigated. This is mainly due to the main characteristic of the original MIL-101 (Cr): oversized cages. In general, the large cavities in cage-type MOFs such as MIL-101 (Cr) are separated by smaller windows.

During the ion separation process, the diffusion of the target ions through the cavities could be controlled by the size-sieving effect of the windows [START_REF] Xiao | UiO-66-(COONa) 2 membrane with programmable ionic channels for lithium ion-selective transport[END_REF]. A competent MOF should have window sizes that allow target ions to pass and prevent larger non-target ions from passing [START_REF] Zhao | Metal-organic framework based membranes for selective separation of target ions[END_REF]. Unfortunately, the smaller cages of the MIL-101 (Cr) have pentagonal windows with a free aperture of ~ 12 Å, while the larger cages have both pentagonal and hexagonal windows with a free aperture of ~14.5 Å by 16 Å [START_REF] Férey | A chromium terephthalate-based solid with unusually large pore volumes and surface area[END_REF]. Compared to the size of the hydration diameter of many typical target ions (such as Li + 7.64 Å, Ni 2+ 8.08 Å, Ca 2+ 8.24 Å and Al 3+ 9.60 Å), these large windows almost make the passage for all ions. This results in poor metal ion separation performance.

To overcome this drawback, modification on the parent MIL-101 (Cr) is required. Approaches such as organic ligand functionalization [START_REF] Zhu | MOF-positioned polyamide membranes with a fishnet-like structure for elevated nanofiltration performance[END_REF], nanocomposite fabrication [START_REF] Song | Doping MIL-101 (Cr)@ GO in polyamide nanocomposite membranes with improved water flux[END_REF], and temperature adjustment [START_REF] Polyukhov | Precise measurement and controlled tuning of effective window sizes in ZIF-8 framework for efficient separation of xylenes[END_REF] have been applied for the controllable tuning of the porosity of MOFs, which will further modify the properties (such as hydro-stability, selectivity of different gases/ions) of MOFs. Beyond these methods, an alternative option to solve this problem is the encapsulation of ionic liquids (ILs). ILs encapsulation is a post-synthetic modification process, in which organic cations and organic/inorganic anions are encapsulated onto the CUS (coordinate unsaturated site) of MOFs. By encapsulating these ionic liquid guests onto the MOF framework, the CUS is occupied, the pore size distribution is tailored, the ion exchange property as well as the ionic conductivity is improved and the electrostatic repulsion between the target ions and the charged membrane surface is enhanced [START_REF] Zhao | Metal-organic framework based membranes for selective separation of target ions[END_REF]. Nowadays, ILs encapsulation on MOFs (referred to as IL-MOFs) based membranes have been widely used in many applications, such as IL-MOF-5 membrane for biogas upgrading [START_REF] Sampaio | Impact of MOF-5 on pyrrolidiniumbased poly (ionic liquid)/ionic liquid membranes for biogas upgrading[END_REF], IL-IRMOF-1 membrane for CO2 capture [START_REF] Gupta | Metal-organic framework supported ionic liquid membranes for CO 2 capture: anion effects[END_REF], IL-ZIF-8 membrane for gas screening, and IL-UiO-66-NH2 membrane for air-dehumidification [START_REF] Park | Highly H 2 O permeable ionic liquid encapsulated metal-organic framework membranes for energy-efficient air-dehumidification[END_REF]. However, no study has focused on the lithium recovery using IL-MOFs based TFN membranes. All these limitations mentioned above

Experimental section

Materials and chemicals

Commercially available hydrophilic polyvinylidene fluoride (PVDF) substrate was purchased from Merck, all chemicals were of analytical grade and used without further purification.

Chromic nitrate nonahydrate (Cr(NO3)3•9H2O, 99%), terephthalic acid (H2BDC, C6H4-1,4-(CO2H)2, 98%, H2BDC), ammonium fluoride (NH4F, ≥ 98%), piperazine (C4H10N2, 99%, PIP), 1,3,5-Benzenetricarbonyl Trichloride (C6H3(COCl)3, 98%, TMC), dimethylformamide (DMF, 99.8%), ethanol (C2H5OH, ≥ 99.8%), concentrated hydrochloric acid (HCl, 37%), hexane (CH3(CH2)4CH3, ≥ 97%) and all the ionic liquids (ILs) were purchased from Merck. S1.

MOF synthesis

Original MIL-101 (Cr)

Hydrothermal reaction method was used for the synthesis of original MIL-101 (Cr) [START_REF] Férey | A chromium terephthalate-based solid with unusually large pore volumes and surface area[END_REF]. Firstly, equimolar (0.01 mol) of chromic nitrate nonahydrate (Cr(NO3)3•9H2O), terephthalic acid (H2BDC, C6H4-1,4-(CO2H)2) and concentrated HCl were mixed in 48 ml of deionized water.

The mixture was stirred for 30 mins under ambient condition. Secondly, the mixture was transferred into the liner, tightly sealed in the Teflon-lined stainless-steel autoclave reactor, and heated under 220 °C for 16 h. Thirdly, the autoclave was cooled down naturally. The mixture was filtrated from the solution and crystalline green solid was obtained. It was noted that a certain amount of recrystallized or unreacted H2BDC was trapped both inside/outside the pores of MIL-101 (Cr). These impurities always lead to a low yield and poor quality of the final product; therefore, rigorous purification procedures were needed. Initially, the mixture was filtered consecutively through the large pore fritted glass filter (no.2) and small pore (no.5) paper filter. Next, the green solid was eluted with hot dimethylformamide (DMF) and ethanol (three times). Finally, the as-synthesized MIL-101 (Cr) was dried at 80 °C overnight and activated at 160 °C for 5 h under vacuum conditions. The activation process was designed to remove water vapour, residual reagent and any other impurities. Dehydration 1 g of activated MIL-101 (Cr) was immersed in 200 ml of ammonium fluoride (NH4F, 1 M) and stirred at 80 °C for 24 h. This dehydration process aimed to create the coordinatively unsaturated chromium sites (CUS) at the secondary building unit (SBU) of the MIL-101 (Cr).

The dehydrated MIL-101 (Cr) was directly washed with hot ethanol (3 x 50 ml) without cooling, dried at 80 °C overnight and vacuum-heated at 160 °C for 5 h.

Ionic liquid encapsulation

The wet-impregnation method was used to encapsulate the ionic liquids onto MIL-101 (Cr), typically using 1 g of activated dehydrated MIL-101 (Cr) and 1 g of 1-Butyl-3-Methylmidazolium chloride ([BMIM] + [Cl] -) dispersed in 100 ml of ethanol liquor. The mixture was stirred for 24 h at ambient pressure and temperature to encapsulate the ILs onto the CUS of the dehydrated MIL-101 (Cr). To make a better ILs encapsulation in the MOFs, the original MOFs are first dispersed in 50 ml of ethanol liquor and stirred for 15 min, and the ILs are dispersed in 50 ml of ethanol liquor and stirred for 15 min. Next, these two solutions are mixed together and stirred at 200 rpm (the stirring speed can neither be too slow nor too furious). The IL-MOFs sample was then filtrated, washed with ethanol (2 x 50 ml), dried at 80 °C overnight, and activated at 160 °C for 5 h, to obtain [BMIM] + [Cl] -type ILs encapsulated MIL-101 (Cr) with an impregnation weight ratio of 1:1, nominalized as "1:1 [BMIM][Cl]-MIL-101 (Cr)". It is noted that the ILs encapsulation procedures remained the same for all the IL-MOFs materials, but with varying types and amounts of ILs.

MOF-TFN membranes fabrication

The development of MOF-TFN membranes involved four main steps: (i) solution preparation.

Solution A: 100 ml aqueous solution containing 0.1% (w/v) original or modified MIL-101 (Cr), 0.2% (w/v) piperazine (PIP) and deionized water was prepared by sonication. Solution B: 100 ml of organic solution was prepared by dissolving 1,3,5-benzenetricarbonyl trichloride (0.15% (w/v)) in hexane; (ii) vacuum filtration. 10 ml of solution A was poured onto the vacuum filtration vessel and filtered through the PVDF substrate; (iii) interfacial polymerization (IP): 6 ml of solution B was added to the PIP-MOFs-embedded PVDF substrate for 1 min. Thus, the polyamide layer of the MOF-TFN membrane was obtained by interfacial polymerization of a PIP (piperazine)/MOF aqueous phase and a TMC (1,3,5-benzenetricarbonyl trichloride/trimesoyl chloride) organic phase; and (iv) thermal treatment. Excess organic liquids were removed, the membrane was heated at 70 °C for 5 min (annealing treatment). To test the effect of the MOF loading amount, different amounts of MOF nanofillers were added to the PVDF substrate by varying the volume (5 ml, 10 ml and 15 ml) of solution A, and the as-prepared MOF-TFN membranes were designated as M5, M10 and M15, respectively.

Characterization

MIL-101 (Cr) based MOFs

The crystallographic structure of the MIL-101 (Cr) based MOFs was determined by X-ray diffraction (XRD). The microstructure, morphology and particle size of the MOFs were investigated by FESEM (Field Emission Scanning Electron Microscopy). The functional groups of the MOFs were tested by FTIR (Fourier Transform Infrared Spectroscopy) characterization. The thermal stability of the original and modified MOFs was tested by TGA (Thermal Gravimetric Analysis) and their charging properties were investigated by Zeta potential analysis. In addition, the N2 adsorption/desorption experiment are conducted by ASAP Tri-star II 3020 at 77 K to determine the porosity of the MOFs. To remove any undesirable adsorbed vapours and water, the sample is outgassed at 160 ℃ for 3 h before N2 adsorption experiment. The N2 isotherms data can be deduced to calculate adsorbent-surface area by using BET (Brunuer-Emmet-Teller) equation. Total pore volume is obtained under saturation conditions (𝑃/𝑃 𝑠 = 1), which is equivalent to the total liquid N2 adsorbed in the MOF sample. The liquid volume is calculated by

𝑉 𝑙𝑖𝑞 = 𝑃 𝑎 𝑉 𝑎𝑑𝑠 𝑉 𝑚 𝑅𝑇
, where 𝑃 𝑎 is the ambient pressure, 𝑉 𝑎𝑑𝑠 is the volume of N2 adsorbed, 𝑉 𝑚 is the molar volume of liquid of N2 with a value of 3.47 × 10 -5 m 3 /mol, R defines the gas constant and T is the temperature. Moreover, the average pore size (𝑟 𝑝 ) is calculated by

𝑟 𝑝 = 2𝑉 𝑙𝑖𝑞 𝐴 𝑠
, where 𝐴 𝑠 is the BET surface area of the adsorbent sample. In addition, the micropore volume is calculated as Vmicropore = (YINT cm 3 /g STP) x (D cm 3 liquid/cm 3 STP), where YINT is the Y-intercept obtained from the Langmuir surface area transformation model and D is the density conversion factor.

MOF-TFN membranes

The MOF additive layer as well as the chemical composition of the uppermost surface of the TFN membrane were verified by XPS (X-ray Photoelectron Spectroscopy). ATR-FTIR (attenuated total reflection-Fourier transform infrared) technique was used to determine the MOF-TFN membrane's functional groups for wavenumbers 4000 to 650 cm -1 . X-Ray Fluorescence Spectrometry was applied to determine the elemental composition (Cr) of the TFN membrane. The MOF-TFN membrane's surface morphology and thickness were measured by FESEM, its wettability (surface hydrophilicity) was tested via contact angle analysis, and its surface roughness was analyzed by AFM (atomic force microscopy) technique using a scan size of 10 µm × 10 µm under NCM (non-contact) mode.

Lithium recovery experiments

Metal ion separation

The metal ion separation experiments were carried out using the commercially available high pressure (HP4750) stirred cell apparatus from STERLITECH (Figure S2). In general, the IL-MOF enabled TFN membrane was placed on the porous stainless steel membrane support and fixed to the cell bottom. Feed solution (simulated LIBs leaching solution) was added to the cell body. After the whole apparatus was well sealed, dry nitrogen gas (99.999%, 2.5 to 15 bar) was supplied from the top of the cell. The feed solution was then flushed through the membrane, discharged through the permeate tube and collected in the beaker. During the experiment, the beaker was placed on the balance, which was connected to built-in weight-time analysis software. This automatically recorded the change in weight of the permeate solution as a function of time for further derivation of water flux and permeability. The concentration of metal ions in the permeate solution was measured by ICP (Inductively Coupled Plasma) analysis.

Regeneration and fouling test

Regeneration and fouling test: After the metal ion separation experiments, the used MOF-TFN membrane was placed in the deionized water and stirred at ambient conditions for regeneration purposes. During stirring in deionized water, the hydrodynamic shear stress generated by the stirring tends to detach the contaminants from the membrane surface as well as from the pores of the MOF. Therefore, the recovered membrane can then be used for the next cycle. Metal ion rejection experiment, water flux and permeability were compared after each regeneration cycle at 7.5 bar. The fouling performance of TFN membranes was mainly influenced by two factors, namely feed solution composition (type/concentration of foulant) and hydrodynamic operating conditions (such as cross-flow velocity). In this work, the fouling performance of the asmanufactured membrane was tested using BSA (bovine serum albumin, 200 mg/L) as a foulant in a multi-ion solution at 10 bar for 4 h continuously. The contaminated membrane was then repeatedly rinsed in water for 1 h.

Ageing test

The first order ageing test of TFN membrane was conducted in two ways: (i) the detachment tendency of nanoparticles was tested using a modified quantification method as reported by Ng et al. [START_REF] Ng | GO/PVA-integrated TFN RO membrane: Exploring the effect of orientation switching between PA and GO/PVA and evaluating the GO loading impact[END_REF] and (ii) the leaching tendency of ionic liquids from MOFs was tested for four filtration cycles. For detachment tendency evaluation, IL-MOF-TFN membrane (M15) was placed in the deionized water (𝑉 𝐻 2 𝑂 = 100 ml) and constantly stirred at the room temperature for 12 h. This procedure aimed to investigate the stability and adhesion of MOF nanoparticles within the TFN membranes. If the interaction was poor, hydrodynamic shear stress created from the agitation tends to detach MOF-based nanoparticles from the membrane. The concentration of chromium ions (𝐶 𝐶𝑟 ) in the solution was tested every 1 h by ICP analysis.

Knowing that the weight percentage of Cr (Cr%) inside MIL-101 (Cr3O(OH)(H2O)2(bdc)3, bdc = benzene-1,4-dicarboxylate) is 21.74% and the total mass of MIL-101 nanoparticle (𝑀 𝑀𝑂𝐹 ) on M15 TFN membrane is 15 mg, the detachment percentage of MOF (DMOF (%)) is calculated as

𝐷 𝑀𝑂𝐹 (%) = 𝐶 𝐶𝑟 •𝑉 𝐻 2 𝑂 𝐶𝑟%•𝑀 𝑀𝑂𝐹 × 100% (1)
In addition, for leaching tendency test of ionic liquids from MOFs, in each cycle, 250 ml of simulated LIBs leaching solution was purged through the membrane at the transmembrane pressure of 5 bar. The lithium concentration of the permeate solution was measured by ICP and the transmittance intensity of the IL-MOF-TFN membranes were evaluated by ATR-FTIR characterization before and after each filtration cycle. The area of each ATR-FTIR band has been calculated using OriginPro software between the ATR-FTIR profile and a baseline corresponding to the maximum transmittance.

Membrane performance evaluation

Separation factor (Selectivity, 𝑺 𝑴 𝟏 ,𝑴 𝟐 )

𝑆 𝑀 1 ,𝑀 2 = 𝑐 𝑀 1 ,𝑝 /𝑐 𝑀 2 ,𝑝 𝑐 𝑀 1 ,𝑓 /𝑐 𝑀 2 ,𝑓 (2)
where 𝑐 𝑀 1 ,𝑝 and 𝑐 𝑀 1 ,𝑓 stand for the concentration of metal ion M1 in the permeate and feed solution, respectively. 𝑐 𝑀 2 ,𝑝 and 𝑐 𝑀 2 ,𝑓 indicate the concentration of metal ion M2 in the permeate and feed solution, respectively. Hence, 𝑆 𝑀 1 ,𝑀 2 = 1 means that the membrane has no separation effect for M1 and M2 ions. On the other hand, 𝑆 𝑀 1 ,𝑀 2 > 1 suggests that M1 ions penetrate the membrane preferentially over M2 ions [START_REF] Li | A positively charged composite nanofiltration membrane modified by EDTA for LiCl/MgCl2 separation[END_REF].

Water flux (Jw, L/(m 2 •h) or LMH)

𝐽 𝑤 = ∆𝑉 𝐴 𝑚 •∆𝑡 ( 3
)
where ∆V is the changing volume of permeate solution (L), Am denotes the effective membrane surface area (0.0009 m 2 ) and ∆t stands for the permeation time (s) [START_REF] Vital | Treatment of acid mine drainage by forward osmosis: Heavy metal rejection and reverse flux of draw solution constituents[END_REF].

Water permeability (A, L/(m 2 •h•bar))

𝐴 = ∆𝑉/(𝐴 𝑚 • ∆𝑡 • ∆𝑃) ( 4
)
where ∆V is the volume of permeate solution (L), Am stands for the effective surface area of the membrane, ∆𝑡 indicates the permeation time (s) and ∆P represents the system pressure (bar) [START_REF] Ni | Highly hydrophilic thin-film composition forward osmosis (FO) membranes functionalized with aniline sulfonate/bisulfonate for desalination[END_REF].

Flux recovery rate (FRR, %)

𝐹𝑅𝑅 = ( 𝐽 𝑤2 𝐽 𝑤1 ) × 100 ( 5
)
where Jw1 is the initial water flux of the fresh membrane and Jw2 is the subsequent water flux of the membrane after fouling [START_REF] Khoo | Eco-friendly surface modification approach to develop thin film nanocomposite membrane with improved desalination and antifouling properties[END_REF].

Results and discussion

Characterization on MIL-101 (Cr) based MOFs

In this section, 2:1 [BMIM][AlCl4]-MIL-101 (Cr) is selected as an example, other characterization results such as PXRD, FTIR, SEM, N2 adsorption and TGA for all the ionic liquid modified MIL-101 (Cr) are elaborated in the supporting document (Figure S3, Figure S4, Figure S5, Table S2 and Figure S6, respectively). Figure 1(a) shows the PXRD (powder X-ray diffraction) profiles of the pristine MIL-101 (Cr) and IL-MOF. Based on the result, peaks appearing near 5.5°, 6.1°, 8.8°, 9.4°,10.7°, 16.9° and 18.9 ° agree with those reported in the literature [START_REF] Férey | A chromium terephthalate-based solid with unusually large pore volumes and surface area[END_REF], which proves that the original MOF is well developed. Similar XRD profiles are found between original and modified MOFs. Therefore, the structure integrity of the MIL-101 (Cr) nanoparticle is not distorted by the ionic liquid encapsulation work. The FTIR plots of the parent MIL-101 (Cr) and IL-MOF are shown in Figure 1(b). Peak at 577 cm -1 is ascribed to the Cr-O vibration. The band appearing near 749 cm -1 and 1117 cm -1 is related to the 𝛾(C-H) and 𝜎(C-H) vibrations of aromatic rings, respectively. Additionally, C=O group vibration is responsible for the band near 1635 cm -1 . Furthermore, due to the existence of dicarboxylate linker inside the MOF structure, band appearing at 1392 cm -1 corresponds to the symmetric (O-C-O) vibration. These FTIR peaks are consistent with those reported by other work [START_REF] Vu | Isomorphous substitution of Cr by Fe in MIL-101 framework and its application as a novel heterogeneous photo-Fenton catalyst for reactive dye degradation[END_REF][START_REF] Niknam | Metal-organic framework MIL-101 (Cr) as an efficient heterogeneous catalyst for clean synthesis of benzoazoles[END_REF].

It is observed that besides the original distinct peaks, few extra peaks at certain wavenumber are detected for the modified MIL-101 (Cr). This is mainly because of the new generated chemical bonding from the ionic liquid additives and MOF framework.

The morphology as well as the particle size of the original MIL-101 (Cr) are displayed in Figure 1(c.1), from where discrete octahedron with smooth surface is found. It is noted that some crystals with lack angles or split morphology are due to the fabrication defect and a few rodlike shape crystals are faulty MOF particles or recrystallized organic ligand [START_REF] Huang | Adsorption characteristics of metalorganic framework MIL-101 (Cr) towards sulfamethoxazole and its persulfate oxidation regeneration[END_REF]. It is found that the as compared with the parent MOF, IL-MOF exhibits similar octahedral shape with comparable size (Figure 1 Majority of the weight loss (55.87%) is found during this process, the MOF framework collapses and decomposition near 350 °C is observed. Finally, material is carbonized at higher temperature (~ 600 °C) and around 35.52% weight residue is obtained. A similar weight loss profile is observed for the IL-MOF, where a higher weight loss (8.72%, due to the high water affinity of the ionic liquids) is obtained in the first stage and a lower weight residue (28.05%, due to the removal of the ionic liquid at higher temperature) is obtained. These results demonstrate the successful encapsulation of the ionic liquid in the MIL-101 (Cr).

Characterization on MOF-TFN membranes

Chemical structures

The S7. Next, to improve the uniform distribution of IL-MOFs in water, the IL-MOFs based aqueous suspension is prepared by sonication instead of general stirring or shaking before IP reaction.

In addition, during the vacuum filtration, the vacuum suction is operated under a moderate and controllable pressure, and the colloidal suspension is subsequently filtered. All these procedures ensure the homogeneity of the TFN membrane. Furthermore, the homogeneity of the TFN membrane is also supported by the surface outlook of the as-prepared membrane (as shown in Graphical Abstract) as well as the surface morphologies of the TFN membranes (as shown in Figure 4(b.2)). Furthermore, the elemental composition analysis on the original and IL-modified MOF is performed via EDS/elemental mapping technique, and the results are given in Table S8. For reference, TGA curves for pure PVDF substrate, MOF loaded PVDF membrane (without IP reaction) and MOF based TFN membrane (with IP reaction) are shown in Figure S9, where promising thermal stability up to 400 °C are found for all the membranes. and M15, respectively 1, 2 and 3).

Surface roughness

The AFM 3D representation of original MOF based TFN membranes is shown in Figure 5, and the overall surface roughness analysis of all membranes are shown in Figure S10 and Table S3, where the surface roughness is evaluated by root mean square roughness (Rms), average roughness (Ra) and maximum vertical distance (Rz). Table 1 shows that the surface roughness of the membrane increases as the amount of MOF encapsulation increases. The lower roughness value of membrane represents a smoother dispersion of MOF nanofillers on the PVDF substrate. As the amount of MOF encapsulation increases, an obvious aggregation of MOF particles is observed, and the average surface roughness (M15) increases to 0.572 µm (Figure S10 and Table S3). This increased roughness indicates a larger surface area of the MOF-TFN membrane, which has favorable effects on water permeation [START_REF] He | Novel polydopamine/metal organic framework thin film nanocomposite forward osmosis membrane for salt rejection and heavy metal removal[END_REF]. However, this makes it easier for the foulant to adhere to the membrane surface compared to surfaces with lower roughness, thus degrading the antifouling performance of the TFN membrane [START_REF] Vrijenhoek | Influence of membrane surface properties on initial rate of colloidal fouling of reverse osmosis and nanofiltration membranes[END_REF][START_REF] Bi | Thin film nanocomposite membranes incorporated with graphene quantum dots for high flux and antifouling property[END_REF].

Wettability

To test the effect of MOF loading on membrane performance, solution A, as discussed in the Methods section, is used with different volumes (5 ml/10 ml/15 ml) to fabricate the original MOF-based TFN membranes, designated M5, M10 and M15, respectively. Theoretically, the smaller the contact angle, the greater the hydrophilicity (wettability) of the fabricated membrane [START_REF] Guo | Conductive thin-film nanocomposite nanofiltration membrane comprising N-doped graphene quantum dots with relieved concentration polarization for sulfate separation from high-salinity solution[END_REF][START_REF] Mousavi | Water decolorization and antifouling melioration of a novel PEBA1657/PES TFC membrane using chitosan-decorated graphene oxide fillers[END_REF]. From Figure 6(a.1-a.4), it can be observed that as the MOF loading increases, the water contact angle of the membrane decreases and hence the surface wettability increases. Figure 6(b) shows the average water contact angle analysis of TFN membranes, with the pure PVDF substrate tested for comparison. It is reported that the increased hydrophilicity would improve the antifouling performance and water permeability of the membrane [START_REF] Wang | Solvent resistant hydrolyzed polyacrylonitrile membranes[END_REF]. The overall water contact angles of all membranes are shown in the supporting documents (Figure S11 and Table S4). performance is obtained at the median encapsulation ratio (2:1). This is mainly due to the fact that the large ionic liquid encapsulation ratio of 2:1 has already reached the MOF encapsulation limit. After that, any more ionic liquid will not be successfully encapsulated into the MOF framework and it may also degrade the ionic liquid-MOF interaction. The overloaded ionic liquid will also occupy excess pore space, preventing lithium ions from permeating through the membrane surface. Therefore, decreased lithium selectivity is found for both the 3:1 Taken together, these results suggest that the lithium recovery performance of the modified MOF-based TFN membrane is closely related to the type and amount of encapsulated ionic liquid, which is internally controlled by the ionic liquid property (such as size and compatibility)

Lithium recovery performance

Effect of ionic liquid

[BMIM][MeSO3]-MOF
as well as the ionic liquid-MOF interaction. Based on the solubility-diffusivity theory, there are two continuous steps in pressure-driven ion transfer across TFN membranes: (i) adsorption and dissolution of ions at the membrane surface and (ii) diffusion through the membrane channels [START_REF] Zhao | Electric field-based ionic control of selective separation layers[END_REF]. The electrostatic repulsion between the ions and the membrane plays a crucial role in the selective separation of metal ions. The surface charge of the TFN membrane affects the retention and transport of metal ions. Based on zeta potential analysis (Figure 9(c.1)), the TFN membrane surface is positively charged under acidic condition (2 ≤ pH ≤ 6). Theoretically, due to the electrostatic repulsion force, a more positively charged membrane surface tends to provide a stronger rejection effect for positive ions, especially divalent ions such as Ni 2+ /Co 2+ /Mn 2+ . In fact, many works have pointed out that positively charged membranes with enhanced electrostatic repulsion are suitable for removal of multivalent cations from wastewater [START_REF] Li | Membrane-based technologies for lithium recovery from water lithium resources: A review[END_REF][START_REF] Campbell | Hybrid polymer/MOF membranes for Organic Solvent Nanofiltration (OSN): Chemical modification and the quest for perfection[END_REF]. MOFs with cationic functional groups and positively charged metal centers are usually adopted for the preparation of positively charged membranes. ILs often contain such cationic functional groups (such as hydroxy and amine

Separation mechanism

Effect of other relevant factors

Overall, the lithium recovery efficiency of the nanofiltration (NF) system is controlled by three factors: (i) membrane properties (such as surface roughness, wettability and antifouling behavior); (ii) metal ion properties (such as diffusivity and size); and (iii) operating conditions (such as filtration pressure, temperature and time). In addition to the revised membrane properties discussed above, the difference in rejection efficiency between Li + and other divalent metal ions (such as Ni 2+ , Co 2+ and Mn 2+ ) is also attributed to the properties of these ions.

Properties related to metal ion separation in aqueous environments, such as hydration radius and diffusivity, are presented in Table S5 for a comprehensive understanding. It can be observed that Li + has the smallest hydrated radius and Stokes radius compared to the divalent metal ions. Due to the sieving mechanism (or size exclusion effect) of the TFN membrane, smaller Li + easily permeate through the membrane while the majority of larger divalent metal ions are blocked. In addition, the highest diffusivity of Li + result in the lowest retention by the TFN membrane. Furthermore, it has been reported by Zheng et al. [START_REF] Zheng | Selective removal of heavy metals from saline water by nanofiltration[END_REF] that the precipitation of the metal hydroxides would also affect the lithium recovery efficiency. In that work, they report that based on the solution-diffusion model, the solute firstly sorbs on the membrane surface on the feed side and diffuses through the membrane matrix. Finally, the solute desorbs at the permeate side of the membrane. Thus, the separation efficiency is governed by the solubility and diffusivity of the solutes. It should be noted that the anions of the heavy metal salts used in that work are chloride and nitrate (in our work it is chloride). Compared with divalent heavy metal cations, H3O + has a smaller charge and a smaller size, making it is easier to pass through the membrane to achieve the charge balance with Cl -or NO3 -in the permeate solutions. As the majority of the larger divalent metal ions are retained on the feed side, H + (also of smaller size) preferentially diffuse across the membrane to balance the anions in the permeate solution. Therefore, both divalent metal ions and OH -ions concentrations increase at the porous surface. Consequently, precipitation of divalent metal hydroxide occurs when Ksp (solubility product constant) is reached and rejection of metal ions occurs. In addition, other factors such as pH and concentration of the feed solution, transmembrane pressure, and operating time also affect the lithium recovery efficiency. For example, Wu et al. [START_REF] Wu | Three-dimensional macroporous wood-based selective separation membranes decorated with well-designed Nd (III)-imprinted domains: A high-efficiency recovery system for rare earth element[END_REF] reported that a low pH (< 7) was favorable for lithium ions to pass through the membrane because the Li + recognition sites on the membrane surface were protonated at low pH and prevent Li + from binding to the membrane. In another study, Bi et al. [START_REF] Bi | Separation of magnesium and lithium from brine with high Mg2+/Li+ ratio by a two-stage nanofiltration process[END_REF] reported that low pH (< 7) was preferable for the separation of Li + and Mg 2+ , due to the elevated dielectric exclusion to multivalent ions. The pH of our LIB leaching solution is 3.51, making it suitable for the recovery of lithium from other divalent metal ions. On the other hand, Kumar et al. [START_REF] Kumar | Downstream recovery of Li and value-added metals (Ni, Co, and Mn) from leach liquor of spent lithium-ion batteries using a membrane-integrated hybrid system[END_REF] reported that increasing the transmembrane pressure from 5 to 10 bar resulted in about a 6% increase in rejection efficiency for divalent metal ions (such as Ni 2+ , Co 2+ and Mn 2+ ) and a marginal retention effect for monovalent metal ions (Li + ). This study showed an increased separation efficiency of Li + over these divalent metal ions. A reasonable explanation for this phenomenon is that the uncoupling of the solvent and solute fluxes, as well as the solutiondiffusion mechanism, caused the solvent flux to increase at higher pressures and the solute flux to remain almost the same. Thus, for a constant feed solution concentration, the rejection rate of the solution was increased (especially for divalent metal ions with larger size and lower diffusivity). In addition, it is known that membrane fouling would reduce the rejection efficiency for all metal ions over long periods of operation. However, this problem could be overcome by applying membrane regeneration. In this study, the transmembrane pressure is maintained at 5 bar to achieve both the promising lithium recovery and relatively fast water flux at low pressure. Membrane fouling is mainly attributed to the accumulation of heavy metal ions on the surface of the TFN membrane. It is well known that the fouling susceptibility of TFN membrane is related to the interplay of surface electrostatic repulsion, steric hindrance, surface tension and wettability. [78] The improved fouling resistance and reversibility of the TFN membrane is mainly attributed to two facts: (i) the selective coating of the polyamide with hydrophilic IL-MOF nanoparticle additives creates a hydrated thin film. The hydrated thin film prevents the foulant from adsorbing on the membrane as the water movement consumes the free energy of the system; [79] and (ii) the enhanced electrostatic interaction between the charged membrane surface and the BSA foulant prevent the BSA from depositing on the membrane. Both factors result in improved fouling control and extended TFN membrane life.

Water permeance, regeneration, antifouling performance

Antiaging performance

The investigation on the leaching tendency of ILs from MOFs was performed on 2:1

[BMIM][AlCl4]-MOF TFN membrane after multiple separation cycles by ATR-FTIR analysis, and have been compared to the fresh IL-MOF TFN membrane. As shown in Figure 11(a), the peak at 1617 cm -1 is more intense because of C=C and N=C=N stretching of the imidazolium cation ring of the IL. C=C and C=N stretching of the imidazolium ring are also responsible of the bands at 1545 and 1509 cm -1 . Symmetric and asymmetric stretching of CH2 and CH3 in the IL cause the intensification of the bands at 1470 cm -1 and 1440 cm -1 . The peak at 1166 cm -1 also covers the CH3-N stretching of [BMIM] + in addition to the CF2 stretching of PVDF. C-N stretching vibration is present in the band at 829 cm -1 . The peak at 747 cm -1 and the one appearing at 659 cm -1 are related to plane and out-of-plane imidazolium bending, respectively.

For each ATR-FTIR bands, the more the membrane was used, the more the intensity of the band decreases (transmittance increases). This may indicate that the IL-MOF layer is slightly washed and becomes thinner after separation test. Areas of characteristic ATR-FTIR bands have been calculated and compared between each membrane before and after filtrations, as illustrated in Figure 11(b). The calculated areas are also given in the supporting documents Table S6. Averaged over all peaks, after the 1 st filtration the membrane lost 1.6% for each FTIR band, 5.8% more between the 1 st and the second filtration, 5.9% after the 3 rd one and 1.5% between the 3 rd and the 4 th filtration. One can also note that the decrease of ATR-FTIR intensity and area are not constant from one separation test to another.

Detachment of nanoparticles not only results in surface defects of membrane, but also causes pollution to the permeate solution.

Comparison study

The state-of-the-art membrane-based technologies for lithium recovery from water resources are classified into seven categories, namely permselective exchange membrane capacitive deionization (PSMCDI) [START_REF] Shi | Efficient lithium extraction by membrane capacitive deionization incorporated with monovalent selective cation exchange membrane[END_REF], selective electrodialysis (S-ED) [START_REF] Zhao | Separating and recovering lithium from brines using selective-electrodialysis: Sensitivity to temperature[END_REF], membrane distillation crystallization (MDC) [START_REF] Cerda | Recovering water from lithium-rich brines by a fractionation process based on membrane distillation-crystallization[END_REF], ion sieve membrane (ISM) [START_REF] Zhao | Synthesis of porous fiber-supported lithium ion-sieve adsorbent for lithium recovery from geothermal water[END_REF], ion imprinted membrane (IIM) [START_REF] Yang | An effective lithium ion-imprinted membrane containing 12-crown ether-4 for selective recovery of lithium[END_REF], supported liquid membrane (SLM) [START_REF] Zante | Highly selective transport of lithium across a supported liquid membrane[END_REF] and nanofiltration (NF) membrane [START_REF] Wang | Novel positively charged metal-coordinated nanofiltration membrane for lithium recovery[END_REF].

Compared to other membrane technologies, NF is the only commercially available large-scale lithium recovery process due to its high technological maturity, high cost efficiency and low operational complexity [START_REF] Li | Membrane-based technologies for lithium recovery from water lithium resources: A review[END_REF]. Criteria such as lithium selectivity, permeability, stability, antifouling, antiaging and regeneration performance are important for TFN membranes used in the NF field for lithium recovery. These criteria are closely related to the TFN membrane properties such as wettability, surface roughness, surface charge, and nanoparticle detachment tendency. For example, higher surface roughness leads to higher surface area, which leads to higher water permeability [START_REF] He | Novel polydopamine/metal organic framework thin film nanocomposite forward osmosis membrane for salt rejection and heavy metal removal[END_REF]. Over the past decades, it has been known that higher surface roughness would degrade the antifouling performance of the TFN membrane because foulants would more easily adhere to the rougher surface. Recently, however, Gan et al. [START_REF] Gan | Does surface roughness necessarily increase the fouling propensity of polyamide reverse osmosis membranes by humic acid?[END_REF] proposed that a lower fouling tendency was observed in the rough membrane containing nanovoids, which was attributed to the weakened "funnel effect" as well as the reduced average localized flux over the membrane surface. In our work, the average surface roughness of IL-MOF-TFN membranes is comparable to that of MOF-TFN membranes (Figure S10 and Table S3). The higher water permeability and better antifouling performance are mainly attributed to the IL additives. In addition, the fabrication of defect-free TFN membranes is crucial for the sizesieving-based resource recovery process in the aqueous environment. For example, Aljubran et al. reported a defect-free interfacially-polymerized TFC membrane with ultrahigh As (III) rejection (> 99.8%) [START_REF] Aljubran | Highly efficient size-sieving-based removal of arsenic (III) via defect-free interfacially-polymerized polyamide thin-film composite membranes[END_REF]. The surface defects of the TFN membrane are closely related to the loading level of the nanoparticles. Neither too little (not enough to cover the membrane surface uniformly) nor too much (tends to form aggregates) of nanoparticle loading would cause defects. In this work, membranes with different loading amounts of IL-MOF nanofillers are characterized by various techniques (such as AFM and SEM), and membranes with the optimized IL-MOF loading are used for further investigation. Furthermore, the performance of the TFN membrane is directly related to the nanoparticle materials [START_REF] Mills | Recent advances in responsive membrane functionalization approaches and applications[END_REF]. For example, Shao et al. [START_REF] Shao | Dispersant promotes mild formation of aminated-carbon quantum dots nanofiltration membranes for high-efficient resource recovery[END_REF] used the dispersant-poly (maleic acid-co-acrylic acid) sodium slat (PMAS) to promote the membrane formation. The PMAS was found to improve the particle deposition behaviour and interfacial compatibility. Research works have reported that ILs [START_REF] Zante | Separation of lithium, cobalt and nickel from spent lithium-ion batteries using TBP and imidazolium-based ionic liquids[END_REF][START_REF] Zante | Lithium extraction from complex aqueous solutions using supported ionic liquid membranes[END_REF] or MOFs [START_REF] Hou | Lithium extraction by emerging metal-organic framework-based membranes[END_REF]

Conclusions

This paper demonstrates a tailorable and hierarchical approach to the fabrication of ionic liquid encapsulated MIL-101 (Cr) based thin film nanocomposite membranes for lithium recovery.

The fabrication and characterization of the nanoparticles and membranes, as well as the lithium recovery experiments are reported. Compared to the original MOF-based TFN membrane, the main improvements of the ionic liquid encapsulated membranes are summarized as follows:

(i) the modified TFN membrane shows promising mechanical strength and flexibility with improved sieving effect and electrostatic repulsion to divalent ions;

  provide the motivation to propose one comprehensive study on IL-MOFs based TFN membranes, from MOFs modification, membrane fabrication, characterization to the lithium recovery performance evaluation. Based on the above introduction, the main objectives of this work include: (i) synthesis and modification (ILs encapsulation) on the original MIL-101 (Cr) MOF; (ii) development of MIL-101 (Cr) based TFN membrane; (iii) characterization of the MOF particles and IL-MOF based TFN membranes; (iv) test the effect of ionic liquid on the performance of TFN membranes; and (v) evaluation on the lithium recovery performance in terms of water permeability, lithium selectivity, antifouling behavior and antiaging performance.

  Collectively, all imidazolium-based ILs used in this work contained the identical cation of 1-Butyl-3-methylimidazolium [BMIM] + , but had four different anions namely chloride [Cl] -, bromide [Br] -, tetrachloroaluminate [AlCl4] -, and methanesulfonate [MeSO3] -. Two 1-Ethyl-3methylimidazolium [EMIM] + based ionic liquids with chloride [Cl] -or bromide [Br] -as anions were also used. The molecular structures of these ionic liquids are shown in Figure S1. All chemicals are of analytical grade and used without further purification. Furthermore, the feed solution components were simulated based on the real LIBs (NMC) leaching solution, which is furnished in Table

  Figure 1(e), where a three-stage weight loss of the original MOF is observed as the temperature

Figure 1 :

 1 Figure 1: Characterization of original and IL encapsulated MIL-101 (Cr) MOF: (a) XRD, (b)

  Figure S7. The presence of new peaks compared to the original pure PVDF substrate indicates

Figure 2 (

 2 Figure 2(b.1-b.3) shows the XRF curves for the three types of membranes. The main purpose

Figure 2 :

 2 Figure 2: (a.1-.3) ATR-FTIR profiles and (b.1-b.3) XRF curves of pure PVDF substrate, MOF

Figure 3 :

 3 Figure 3: XPS (X-ray photoelectron spectroscopy) spectra of pure PVDF surface, original and

Figure 4 :

 4 Figure 4: (a) Cross-sectional SEM pictures and (b) surface morphologies of MIL-101 (Cr)

Figure 5 :

 5 Figure 5: AFM images of pure PVDF substrate and MIL-101 (Cr) based TFN membranes, with

Figure 6 (

 6 b) also shows that the hydrophilicity of the original MIL-101 (Cr)based TFN membrane could be further improved by ionic liquid encapsulation. The improved hydrophilicity of the ILs-MOF based TFN membrane is mainly attributed to the strong water adsorption ability of MIL-101 (Cr) MOFs and the affinity of the ionic liquid to water.

Figure 6 :

 6 Figure 6: (a) Water contact angle screenshot for pure PVDF substrate and MOF based TFN

Figure 7 :Figure 7

 77 Figure 7: (a) Effect of MOF loading amount and (b) effect of ionic liquid encapsulated PVDF

Figure 8 :

 8 Figure 8: Lithium recovery experiments using various modified MOF based TFN membranes

Figure 8 (Figure 8

 88 Figure 8(a-f) shows the lithium recovery performances of different ionic liquid modified MIL-

( 3 .

 3 [START_REF] Zante | Lithium extraction from complex aqueous solutions using supported ionic liquid membranes[END_REF], +39.1%) and 𝑆 𝐿𝑖 + , 𝑁𝑖2+ (3.45, +33.2%) are obtained. This is because the ionic liquid encapsulation work enhances both the size exclusion effect (by reducing the pore opening of the original MOF) and the electrostatic repulsion (by modifying the membrane surface charge property). The combined effects result in higher lithium selectivity. In addition, [EMIM][Cl] has the smallest molecular size of all six types of ionic liquids. Therefore, a higher encapsulation ratio (3:1) is required for the TFN membrane to achieve optimal performance. Similar results are found for [EMIM][Br] (Figure 3(b), [BMIM][Cl] (Figure 3(c)) and [BMIM][Br] (Figure 3(d)), where the best performance is obtained at the highest ionic liquid encapsulation ratio (3:1). Furthermore, it is found that as the molecular size of the ionic liquid increases (from [EMIM][Cl] to [BMIM][Br]), the lithium selectivity 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ increase up to 5.10, 6.32 and 4.16 for 3:1 [BMIM][Br]-MIL-101 (Cr) based TFN membrane. These results prove that larger ionic liquid with higher encapsulation amount will further enhance the sieving effect and electrostatic repulsion effect, leading to higher lithium selectivity. However, for ionic liquid with even larger molecular size such as [BMIM][MeSO3] (Figure 8(e)) and [BMIM][AlCl4] (Figure 8(f)), the overall optimal lithium recovery

Figure 9 (

 9 Figure 9(a) shows the best lithium recovery performance for each membrane type used in this

  groups) and have a strong affinity to MOFs. This results in more positively charged membrane surface (Figure 9(c.1-c.2)) and enhanced electrostatic repulsion for IL-MOF based TFN membrane. Together, these factors contribute to the improved lithium selectivity of IL-MIL-101 (Cr) incorporated TFN membranes.

Figure 9 :

 9 Figure 9: (a) the highest lithium selectivity of pure PVDF substrate, original and modified MOF

Figure 10 (

 10 Figure 10(a) and Figure 10(b) show the water flux and permeability of the TFN membrane,

Figure 10 :

 10 Figure 10: Performance assessment of original and modified MIL-101 (Cr) based TFN

Figure 11 (

 11 c) shows the indirect evaluation on the detachment tendency of MOF nanoparticles from TFN membrane by tracking the chromium concentration. It is therefore observed that as time passes, the concentration of chromium ions increases linearly (R linear regression with R 2 = 0.9637) from 0.118 mg/L to 0.179 mg/L (less than 0.2 mg/L) from the first hour to the twelfth hour, respectively. It can then be calculated that the detachment percentage of MOF is as low as 0.54% over 12 hours, which proves the promising adhesion between MOF nanoparticles, PA matrix and the substrate. In addition, to test the lithium recovery effect of the TFN membrane, multi-filtration experiments were carried out. Typically, the simulated LIBs leaching solution was used as the feed solution for the first filtration cycle. After that, the permeate solution was collected and used as the feed solution for the second filtration cycle. The permeate solution in the second filtration cycle was then used as the feed solution for the third filtration cycle. Same procedure was applied until the fifth filtration cycle. The lithium ions concentration of the permeate solution after each filtration cycle was tested by ICP and shown in Figure11(d). By repeatedly filtrating the solution, the lithium ions were concentrated. It is found that the lithium concentration in permeate solution increases almost linearly (from 393.3 mg/L to 744.5 mg/L) for the first three filtration cycles. The concentration of lithium ions after the fourth and fifth cycle is 802.7 mg/L (93.9% recovery rate with respect to the feed solution) and 846.2 mg/L (98.9% recovery rate with respect to the feed solution), respectively. All these results discussed above prove that the IL-MOF-based TFN membrane could recover lithium ions from LIBs leachate with promising membrane integrity.

Figure 11 :

 11 Figure 11: (a) ATR-FTIR profiles for 2:1 [BMIM][AlCl4]-MIL-101 based TFN membrane

  can be used alone in the field of membrane-based lithium recovery. In our study, by encapsulating ILs into the MOFs, the larger pore size of the original MOFs is reduced and the leaching tendency of the ILs is decreased. The synergistic effect between ILs and MOFs simultaneously strengthens the TFN membrane. In the recent literature, the water permeability of the majority of TFN membranes ranges from 25.0 L/(m 2 •h•bar) to 55.0 L/(m 2 •h•bar) (ours is 45.0 L/(m 2 •h•bar)), which mainly depends on the types of feed solution, membrane configuration and operating conditions. Finally, it should be noted that our results (lithium selectivity around 10) may not be remarkable compared to other lithium selectivity reported in the literature. The key challenges of ILs encapsulation in the MOFs are (i) to precisely control on the amount of ILs encapsulation; and (ii) to prevent ILs leaching. First of all, ambiguous ILs encapsulation would degrade the performance of the TFN membrane. Insufficient ILs encapsulation resultsin poor 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ , and excess ILs encapsulation leads to the unstable bonding between the IL additives and the MOF structure. Secondly, ILs leaching from the MOF structure would not only cause the decrease of the separation performance, but also pollute the permeate solution. Both challenges could be systematically overcome by precise encapsulation of the ILs into the MOFs, where dehydration and creation of coordinatively unsaturated chromium sites (CUS) of the original MOF are performed. Thus, the ILs are chemically bound to the secondary building unit (SBU) of the MOF. In addition to the challenges mentioned above, another major limitation of this technique is the relatively high cost of ILs for practical implementation and scalability, and this is one of the most common limitations of using ILs for various applications. However, this work provides a novel approach for the fabrication of TFN membranes with tunable size-selective effect. By verifying the type and encapsulation amount of ILs, the synthesized membrane could be used in various applications such as desalination, wastewater treatment, and resource recovery. At present, the use of IL-MOF-based membranes for lithium recovery is still in the early stages of research and laboratory benchmark, at technology readiness level of 3. More efforts should be made on membrane scale-up, economic analysis and industrial implementation aspects. These will likely involve intellectual property development and is beyond the scope of this article.

Table 1 .

 1 The surface roughness parameters of pure PVDF substrate and MIL-101 (Cr) based

	TFN membranes, with different MOF loading amounts (M5, M10 and M15).
	MOF type/amount	Rms (µm)	Ra (µm)	Rz (µm)
	Pure PVDF membrane	0.313	0.240	2.332
	MIL-101 (Cr) (M5)	0.434	0.345	2.524
	MIL-101 (Cr) (M10)	0.622	0.519	3.136
	MIL-101 (Cr) (M15)	0.705	0.572	4.410

  , Co 2+ and Ni2+ . The pure PVDF substrate is also tested for comparison purpose. It can be observed that pure PVDF does not show any obvious separation effect as the Li + selectivity over Mn 2+ , Co 2+ 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ are increased to 1.57, 1.72 and 1.55, respectively. The improved lithium selectivity is mainly due to the improved surface sinuosity of the MOF as well as the polymer additives. The lithium selectivity 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ could be further improved to 1.73, 1.75 and 1.69 respectively as more MOF is loaded (e.g. M10). This is because the surface voids for M10 are filled with more MOF nanoparticles. This makes it more difficult for the larger divalent metal ions to penetrate. However, as the amount of MOF loading continues to increase (e.g. M15), the lithium selectivity 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ start to decrease to 1.49, 169 and 1.48, respectively. This is due to the fact that at excessive MOF loading, the nanoparticles tend to align or aggregate inappropriately (also confirmed by the SEM surface morphology study). Such clusters may act as defect sites on the TFN membrane surface and cause poor selectivity. Therefore, M10 membrane shows the best lithium recovery performance with the optimal MOF loading amount. It is noted that solution PVDF membrane, where the lithium selectivity 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ are 1.68, 1.67 and 1.61, respectively. However, as with the original MOF-based TFN membrane, not much improvement is obtained in terms of lithium selectivity. Such a problem is mainly caused by the intrinsic shortcomings of the ionic liquid, such as relatively low stability and poor affinity to the polymeric component. In addition, the separation performance of PIP-TMC membranes are shown in FigureS13in the supporting documents, where almost no specific lithium separation are observed versus Mn 2+ (𝑆 𝐿𝑖 + , 𝑀𝑛 2+ = 1.035), Co 2+ (𝑆 𝐿𝑖 + , 𝐶𝑜 2+ = 1.036) or Ni 2+ (𝑆 𝐿𝑖 + , 𝑁𝑖 2+ = 1.028). Overall, membranes prepared by encapsulating only ionic liquid on the PVDF substrate without nanoparticle carriers are unstable and show poor selectivity.

	and Ni 2+ is less than 1.1. By loading original MIL-101 (Cr) to the PVDF surface (e.g. M5),

A containing original and modified MIL-101 (Cr) nanoparticles with a volume of 10 ml is used for the rest of the membrane study. In addition, no significant improvement in terms of lithium selectivity is obtained for the original MIL-101 (Cr) based TFN membrane compared to the pure PVDF membrane. This is mainly due to the fact that MIL-101 (Cr) has an extremely large pore size, which degrades the lithium separation process from other divalent metal ions. Furthermore, six types of ionic liquids are separately encapsulated on the PVDF membrane (without MOF) via IP reaction and tested for lithium recovery experiment. As shown in Figure

7

(b), all six types of ionic liquid encapsulated PVDF membranes show higher lithium selectivity compared to pure PVDF. The best performance is observed for [EMIM][Cl]-

  , 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ is 2.73, 2.81 and 2.59 respectively for 1:1 [EMIM][Cl]-MIL-101 (Cr) based TFN membrane. Similar results are found for 2:1 sample, and when the ionic liquid encapsulation is increased to 3:1, a significant improvement in terms of lithium selectivity 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ (3.57, +30.7%), 𝑆 𝐿𝑖 + , 𝐶𝑜 2+

  and [BMIM][AlCl4]-MOF based TFN membranes. Furthermore, among all the membranes, the 2:1 [BMIM][AlCl4] modified MOF based TFN membrane exhibits the highest lithium selectivity 𝑆 𝐿𝑖 + , 𝑀𝑛 2+ (8.91), 𝑆 𝐿𝑖 + , 𝐶𝑜 2+ (9.94) and 𝑆 𝐿𝑖 + , 𝑁𝑖 2+ (10.08).

Acknowledgements

The authors acknowledge financial support from the SCARCE project, which (i) phase 1 was supported by the National Research Foundation, Prime Minister's Office, Singapore, the Ministry of National Development, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop R&D Initiative as part of the Urban Solutions & Sustainability -Integration Fund [Award No. USS-IF-2018-4] and; (ii) Phase 2 is currently supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award CTRL-2023-1D-01). H.B. thanks Dr. Joseph Jeganroy for the supply of a typical composition of a LIBs (NMC)

(ii) the modified TFN membrane exhibits a fourfold improvement in lithium selectivity (up to 10) over Mn, Co and Ni;

(iii) improved regeneration behavior, permeability (up to 45.0 L/(m 2 •h•bar)), antifouling performance (flux recovery rate FRR up to 96.39%), antiaging and stability behaviors are achieved.

Overall, with this report of high Li + metal ion separation efficiencies on simulated LIBs lixiviates, as well as membrane regeneration, antifouling and antiaging properties, we have already gone well beyond a simple proof of concept, thus demonstrating the potential of the proposed tailorable membrane fabrication method for various metal ion separation applications.

In other words, the as-synthesized IL-MIL-101 (Cr)-based TFN membrane proves to be a promising candidate for efficient lithium recovery, but probably also for other lixiviates.

Further investigation into product quality, operating costs, system stability, refining the ILs encapsulation amount, energy requirements and membrane optimization will be explored in future research.

Conflicts of interest

The authors declare no competing financial interest.


Bénédicte Lebret
email: benedicte.lebret@inrae.fr

Quality attributes of pork and processed products from fat breeds -Examples of local french breeds


Maud Fagny

Marieke L Kuijjer

Maike Stam

Johann Joets

Olivier Turc

Julien Rozière

Stéphanie Pateyron

Anthony Venon

Clémentine Vitte
email: clementine.vitte@inrae.fr

Identifying key tissue-specific, biological processes by integrating enhancer information in maize gene regulatory networks

Background and objectives

Enhancers are key regulators of the spatio-temporal coordination of gene expression, in particular during development. Their regulatory effect is mediated by the binding of transcription factors (TFs), which interact with target gene promoters through 3D-loops over long distances (2kb-1Mb). While enhancers have been identified as key players in the wiring of developmental gene regulatory networks in mammals, this question remains largely unexplored in plants. Transposable Elements (TEs) of various superfamilies have been proposed as a source of new cis-regulatory elements in plants and animals, but whether they contribute to the emergence of tissue-specific gene regulatory networks in plants remains to be fully elucidated.

Data and methods

Fundings and support


Lucile Chauvet

Gwenaelle Randuineau

Armelle Cahu

Olivia Ménard

Yann Le Gouar

Sylvie Guerin

Didier Dupont

Amélie Deglaire

Isabelle Luron Le

La qualité des ingrédients protéiques laitiers impacte la physiologie intestinale et le microbiote d'un modèle animal du nourrisson

teaching and research institutions in France or abroad, or from public or private research centers.

Introduction

  Lucile Chauvet abc , Gwénaële Randuineau b , Armelle Cahu b , Olivia Ménard a , Yann Le Gouar a , Sylvie Guérin b , Didier Dupont a , Marion Lemaire c , Amélie Deglaire a , Isabelle Le Huërou-Luron a STLO, INRAE, Institut Agro-Agrocampus Ouest, Rennes ; b Institut NuMeCan, INRAE, INSERM, Univ Rennes, Saint Gilles ; c SODIAAL International, Centre Recherche & Innovation, Rennes Conflit d'intérêt : L. Chauvet et M. Lemaire sont employées par SODIAAL International Recommandations : allaitement exclusif jusqu'à 4 à 6 mois Seule alternative adéquate lorsque l'allaitement n'est pas possible ou souhaité utilisation d'ingrédients issus lactosérum idéal présente certaines similitudes par rapport au lait humain (absence de GMP, aminogramme, cinétiques digestives) et favoriser la production bénéfique de butyrate par le microbiote La fraction caséique (PPN C) ne doit pas être négligée et mérite d'être plus largement explorée à la vue des effets physiologiques observés (fonctions barrière, immunitaire et de transport des nutriments)


Genotype and feeding affect economic parameters

Higher added value for P vs D pigs ↗ added value with R feeding for D pigs, less for P pigs +5 ct p. 17

  Quality of pork and processed products from local fat breeds University of Guelph -Meat Science & Muscle Biology Club / 30 th March 2023 / Bénédicte Lebret  Pork: mainly consumed as processed products in Europe 55-60% of pork consumption in Italy, 75% in France, 80% in the UK  Historically: promoting preservation of pork → variety of pocedures: curing, smoking, cooking, drying, fermenting… for integral cuts (ham) or minced meat (sausages…) and recipes according to regions, climatic conditions, cultural habits…  Diversity of products -> various quality expectations for the raw material according to process  However, some major physical and biochemical traits affect pork quality  Intramuscular fat content (IMF)  Glycogen content  Properties of muscle fibres and muscle microstructure  Processing of muscle into meat : post-mortem pH decline, proteolysis Lebret & Candek-Potokar, 2022 a, b Pork : a great diversity of products -but common major quality indicators p. 7 Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Influence of post-mortem pH decline on pork technological and eating quality Monin (2004) p. 8 Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Quality of pork and processed products : a complex concept!  Quality is built but can be impaired at all steps from farm to fork  Some antagonisms but also synergies can be found between steps, and between quality attributes -> Diversity of pig production systems, products, and attributes Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Combining genetic and nutritional strategies to improve intrinsic and extrinsic quality attributes of pork p. 10 Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Objectives and partnership of the project  Multi-actor project : Pork quality development from farm to fork -Objectives : improving the sensory and nutritional attributes of pork while contributing to the relocation of feed resources -> image -Partnership: public research, pork producers, animal feed and processing industries; regional funding  From State-of-the art we know that -Effects of individual genetic and production factors: e.g. feeding on intrinsic on pork quality attributes are relatively well established (Warner et al 2017; Lebret & Candek-Potokar, 20221) -Duroc pure or crossbred pigs: good sensory (tenderness) and technological properties (Plastow et al 2005, Gispert et al 2007, Morales et al 2013, Kowalski et al 2020) -Protein/energy intake and composition of dietary fat -> carcass traits, composition of muscle and fat tissues, and nutritional properties of pork (Lebret 2008, Guillevic et al 2009) -Origin of feed protein resources : critical point in the objective of relocation of food production and for the global improvement of the sustainability of pork production  Combining production factors: a way to jointly improve pork quality attributes? p. 11 Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Experimental design  Two pig genotypes (G) : 60 crossbred females (Large White x Landrace) X boars → Duroc (D) selected on growth, feed intake and intramuscular fat content → Pietrain NN (P) selected on growth, feed efficiency, carcass leanness & pork technological pork quality  Two feeding regimen (F) : differing on origin of feed ingredients (Fr vs imported) and nature of protein and fat resources / same proportion of cereals (wheat, maize, barley, wheat bran) → Roc+ (R) : extruded faba beans and lineseed (n-3) + vit E : relocation of resources, pork nutritional value → Control (C) : oilseed meal (soybean, rapeseed, sunflower peeled)  Precision feeding: DLys/NE adjusted weekly on average requirements of each group: blend of high and low protein diets within C & R, distributed ad libitum

  : P<0.001; ** : P<0.01; * : P<0.05; t : P<0.10 ↗ dressing for P vs D pigs (and R vs C) ↗ carcass leanness (↘ backfat) for P vs D pigs p. 13 Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Meat quality traits: pH, water holding capacity and color No PSE meat defect D vs P : ↗ pHu and WHC => higher technological quality esp. Texture and flavour of roasted meat Meat from D vs P pigs: ↗ marbling, ↗ tenderness and juiciness (↘ shear force, pH) P: ↗ flavour (PUFA?) Feeding : no effect on sensory traits p. 16 Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Economic indicators Economic context : experiment (October 2019), actual carcass weights -Feeding costs, Control diets: world prices, R diets: no-GMO soya or sunflower, French origin -Carcass output prices: french pig market + for R pigs: premium for nutritionnal quality label (Bleu Blanc Coeur)

  Pork quality: a complex concept Webinar Pig Progress -6 July 2023 / Bénédicte Lebret Duroc vs Pietrain crossbred pigs -Higher technological and sensory quality -Lower (satisfactory) growth performance and carcass lean meat content, lower economic gain Roc+ vs Control feeding -Slighty improved growth performance, but similar carcass compostion, higher feeding cost -Marked improvement in pork nutritional value, contributes to relocation of resourcesCombining genetic and nutritional strategies DR pigs: jointly improve the sensory, technological, nutritional and image quality attributes of pork -but needs better valuation of their higher sensory qualityPerspectives Evaluation of environmental impacts of the 2 genotypes X 2 feeding systems (in progress)  Multidimensional evaluation : identify synergies or trade-off between quality attributes in a holistic,

Added value (output -feed)/pig, €

	Cold carcass (CC) weight, kg	87.7	80.3	94.5	91.7	G***, F***, GXF*
	Output price/kg CC, €	1.86	1.79	1.92	1.87	G***, F***
	Feed cost/kg CC, €	0.64	0.62	0.60	0.56	G***, F***
	Added value (output -feed)/kg CC, €	1.22	1.17	1.32	1.31	G***, Ft
		107.2	94.2	124.5	120.3	G

***, F***, GxF t


Eric Schmidt
email: schmidt.e@chu-toulouse.fr

Maxime Ros

Emmanuel Moyse

Sylvie Lorthois

Pascal Swider

Bernoulli's Principle Applied to Brain Fluids

Keywords: Bernoulli's principle, Fluid mechanics, Intracranial pressure, Velocity, Energy, Hydrocephalus, Cerebrospinal fl uid

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The fi rst law of thermodynamics states that the conservation of energy, that is, energy of an isolated system, is constant. Resistance is nothing but a transformation of one form of energy to another form: high resistance represents a highenergy transfer and vice versa . In 1738, Daniel Bernoulli published " Hydrodynamica " [ 1 ], which stated a fundamental principle in line with the fi rst law of thermodynamics: the total energy in a fl uid is the same at all points. In other words, the sum of the kinetic energy, gravitational energy, and pressure energy of a fl uid particle is constant along a streamline during steady fl ow, when compressibility and frictional effects are negligible. Despite its simplicity, Bernoulli's principle [ 2 ] has proved to be a powerful tool in fl uid mechanics.

Kinetic energy . Kinetic energy of an object is the energy it possesses because of its motion. It is defi ned as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during acceleration, the body maintains this kinetic energy unless its speed changes.

Gravitational energy. Gravitational energy is the simplest to understand: carry a bucket of water up stairs and the work you have done in part goes into the potential energy of the water.

Pressure energy . Energy and pressure are in fact synonyms. Water under high pressure has more energy than water under low pressure. Although water is considered incompressible, water under pressure is stressed by the pressure. To a small extent, the resultant strain is compressing the water and squeezing the bonds and fi elds in and around the water molecules. Like a bunch of stiff springs, the water absorbs the energy into the springs, which then push back against the container and the surrounding water. The energy stored in the water "springs" is distributed over the mass of the water being squeezed.

The purpose of this paper is to apply in a simple manner Bernoulli's principle to brain fl uids to understand the relationship between intracranial pressure (ICP) and intracranial velocity. What is driving brain fl uids? Pressure or velocity? Is ICP driving cerebral perfusion and CSF fl ow?

Materials and Methods

Bernoulli's equation states that the sum of kinetic energy (Ec) + gravitational energy (Eg) + pressure energy (Ep) is constant [ 3 ]. Let us consider a fl uid fl owing steadily (no pulsatility) in a horizontal (no loss in gravitational energy) rigid (no energy storage) tube. The pressure along the tube is measured using vertical piezometer tubes that display local static pressures. We assume that a virtual tap maintains the fl uid at a stable level within the tank to keep the fl ow steady in the horizontal tube. We applied simple fl uid physics to describe the interplay between pressure and fl ow along the tube. Despite the extreme simplicity of this model, it helps us to understand what drives the movement of a fl uid.

Results

The results are demonstrated in Figs. 1 and2 .

Discussion

Thanks to Bernoulli, we demonstrate that pressure does not drive fl ow. A fl uid does not fl ow along a gradient of pressure or a gradient of velocity. In physics and physiol-ogy a fl uid fl ows along a gradient of energy [START_REF] Burton | Physiology and biophysics of the circulation[END_REF]. The qualitative behavior, termed "Bernoulli effect" [ 5 ], is rather counterintuitive, with a lowering of fl uid pressure in regions where the velocity is increased. An even more surprising fact is that a fl uid can fl ow against a pressure gradient, from high-pressure region to low-pressure region. For example, in Intracranial pressure (ICP) is the pressure within the rigid skull. ICP is used to calculate the cerebral perfusion pressure (CPP) as the difference between mean arterial blood pressure (ABP) and mean ICP. In this CPP approach, pulsatile blood fl ows from the high-energy arterial region (ABP) to the lower-energy venous region (ICP). CPP is easy to explain, calculate, and process at the bedside. However, we should take into account the fact that gauging pressure is an approximation of energy measurement. Using Shepard's approach to hemodynamic energy calculations [START_REF] Shepard | Energy equivalent pressure[END_REF], instead of CPP we should compute an energy-equivalent cerebral perfusion pressure (EECPP) from phasic fl ow and pressure measurements. The hemodynamic energy delivered to the brain by the pulsatile cardiac blood fl ow should be calculated using the following formula: EECPP (mmHg) = (∫fpdt)/(∫fdt), where f is the cerebral blood fl ow (ml/min), p is the internal carotid pressure (mmHg), and dt is the change in time at the end of the fl ow and pressure cycle. Thanks to Bernoulli, Fig. 1 Behavior of a perfect fl uid in a horizontal line system and the changes in local pressure (measured using a piezometer tube) depending on the narrowing or dilation of the tube. We explain the local pressure changes using Bernoulli's principle. ( a ) A perfect fl uid is fl owing in a horizontal tube; hence, there is no gravitational gradient along the tube. A perfect fl uid has no intrinsic loss of energy owing to friction. Bernoulli's principle states that the total energy of the fl uid is constant; the net change in kinetic and pressure energy is therefore null: ΔEc + ΔP = 0. In accordance with Bernoulli's principle, the total energy is constant (E1 = E2 = E3). Owing to mass conservation and the stability of the tube diameter, the mass per unit time is unchanged, and there is no variation in kinetic energy (Ec1 = Ec2 = Ec3). ( b ) As ΔEc = 0, then ΔP = 0; in other words, there is no change in pressure along the tube. The static pressure head measured using a piezometer tube is stable: P1 = P2 = P3. ( c ) A perfect fl uid is fl owing in a horizontal tube with local dilation. Owing to Bernoulli's principle, the total energy is constant (E1 = E2 = E3), ΔEc + ΔP = 0 or ΔEc = -ΔP. Where the tube is dilated, because of mass conservation, the mass per unit time is reduced, i.e., reduced velocity. There is a local drop in kinetic energy, which is not evenly distributed along the line (Ec1 > Ec2 < Ec3). ( d ) As ΔEc = -ΔP, every reduction in kinetic energy is associated with an inverse change in pressure. Ec1 > Ec2 < Ec3 yields P1 < P2 > P3. At ➋ there is a local drop in velocity with a counterintuitive increase in pressure. The static pressure head, measured using a piezometer tube, demonstrates the local pressure augmentation (P1 < P2 > P3). ( e ) A perfect fl uid is fl owing in a horizontal tube with local constriction. Bernoulli's principle states that the total energy is constant (E1 = E2 = E3), ΔEc + ΔP = 0 or ΔEc = -ΔP. Where the tube is constricted, owing to mass conservation, the mass per unit time is increased, i.e., increased velocity, and there is a local increase in kinetic energy that is not evenly distributed along the line (Ec1 < Ec2 > Ec3). ( f ) As ΔEc = -ΔP, every increase in kinetic E is associated with an inverse change in pressure. Ec1 < Ec2 > Ec3 yields P1 > P2 < P3 with a local counterintuitive drop in pressure. The static pressure head, measured using a piezometer tube, demonstrates the local pressure reduction (P1 > P2 < P3)

Ec 1 = E 2 = E 3 > Ec 3 Ec 1 < Ec 2 Bernoulli Narrowing = local increase in Ec Ec 1 = E 2 = E 3 > Ec 3 Ec 1 < Ec 2 Bernoulli Narrowing = local increase in Ec > P 3 P 1 < P 2
Local drop in pressure ∆Ec+∆p = 0 Then : ∆p = -∆Ec energy is a key to understanding fl uid dynamics and should be applied to understand and characterize cerebral perfusion.

1 2 3 1 2 3 a c e f d b Ec 1 = E 2 = E 3 1 2 3 1 2 3 1 2 3 1 2 3 = Ec 3 Ec 1 = Ec 2 E 1 = E 2 = E 3 < Ec 3 Ec 1 > Ec 2 E 1 = E 2 = E 3 < Ec 3 Ec 1 > Ec 2 < P 3 P 1 > P 2 Ec 1 = E 2 = E 3 P 1 = P 2 = P 3 = Ec 3 Ec 1 = Ec 2 Bernoulli Bernoulli
Intracranial pressure is the pressure in the cerebrospinal fluid (CSF) within the rigid skull. CSF is produced by the choroid plexus and is drained down to the venous system by the arachnoid granulations [START_REF] Pollay | The function and structure of the CSF outfl ow system[END_REF]. Consequently, CSF flows along a gradient of energy, from high-energy choroid plexus, through the ventricles, the subarachnoid space, and arachnoid granulations to reach the lower-energy venous blood. Hydrocephalus is supposed to be related to the derangement of CSF flow and increased resistance at various points has been proposed [START_REF] Rekate | A consensus on the classifi cation of hydrocephalus: its utility in the assessment of abnormalities of cerebrospinal fl uid dynamics[END_REF]. The total resistance of CSF flow is the sum of all resistance at various locations, in succession: the foramen of Monro, the aqueduct of Sylvius, the foramina of Luschka and Magendie, the posterior fossa subarachnoid space, the tentorial notch, the subarachnoid space, and finally, resistance at the level of the arachnoid granulations. As mentioned above, resistance is nothing but energy transfer. We know that E1 > E2 > E3. Where the tube is constricted, owing to mass conservation, the mass per unit of time is increased, i.e., increased velocity. At ➋ there is a local increase in kinetic energy (Ec1 < Ec2 > Ec3).

Ec 1 > E 2 Ec 1 > E 2 P 1 > P 2 Ec 1 > Ec 2 = E 3 = E 3 = E 3 = E 3 > P 3 Ec 1 > E 2 Ec 1 < Ec 2 = E 3 = Ec 3 Ec 1 = Ec 2 Viscous Fluid i.e.
( d ) As ΔP = -ΔEc -ε, every increase in kinetic energy is associated with a greater inverse reduction in pressure. Ec1 < Ec2 > Ec3 yields P1 > P2 < P3 with a pressure drop at ➋. The static pressure head, measured using a piezometer tube, demonstrates the local pressure drop (P1 > P2 < P3)

Consequently, CSF transfers energy at various points (see above). To better understand ICP, we should keep in mind Bernoulli's principle and identify the location of energy transfer within the CSF circuit. Interestingly, manipulation of intraventricular pulsatility could lead to hydrocephalus [ 9 , 10 ]. Indeed, an experimental increase in the pressure pulse wave with an intraventricular balloon yielded enlargement of the manipulated ventricle compared with the contralateral ventricle [START_REF] Rocco | Communicating hydrocephalus induced by mechanically increased amplitude of the intraventricular cerebrospinal fluid pressure: experimental studies[END_REF]. One can consider how important CSF pulsatility is with regard to ventricular dilation. On the other hand, the artificial increase in pulse wave is produced by adding external energy to the ventricular system. In other words, this experimental setting artificially augments the energy gradient along the CSF circulation; hence, greater energy transfer is required for CSF to flow. Greater energy transfer is greater resistance, isn't it? Then is this experimental hydrocephalus without obstruction of flow related to an increase in pulse pressure or an underlying increase in CSF resistance? Probably both. There is a growing body of evidence that the "pulsatile energy" is important in understanding and treating hydrocephalus and CSFrelated disorders [START_REF] Wagshul | The pulsating brain: a review of experimental and clinical studies of intracranial pulsatility[END_REF]. ICP should be considered as dualpurpose, with static and dynamic components. Intracranial pressure is a complex modality that contains combined information about the brain and heart, and about cerebral compensatory and blood fl ow regulation mechanisms [START_REF] Czosnyka | Monitoring and interpretation of intracranial pressure[END_REF]. Bernoulli's principle is not an abstract concept that is far from clinical practice. We should be aware and teach that pressure does not drive fl ow. Pressure is one of the easiest physical properties to measure, but pressure does not induce a resumtion of fl uid fl ow. Thanks to Daniel Bernoulli, energy is the key to understanding cerebral fl uid dynamics and helping to decipher ICP.

  Fig. d the fl uid fl ows from P1 to P2 and P1 <P2, in Fig. f it fl ows from P2 to P3 and P2 <P3. Also, a fl uid can fl ow against a velocity gradient from low-velocity region to higher-velocity region (e.g., Fig. d : Ec2 <Ec3). A fl uid does not fl ow along a gradient of pressure or velocity; a fl uid can even fl ow against a gradient of pressure or velocity. A fl uid fl ows along a gradient of energy, from high-energy region to low-energy region. Pressure and velocity represent a part of the total energy. Measurement of a sole pressure or velocity cannot induce resumption of fl uid fl ow. In what way can Bernoulli's principle be applied to brain fl uid?

Fig. 2

 2 Fig.2Behavior of a viscous fl uid in the same system. ( a ) A viscous fl uid is fl owing in a horizontal tube. A viscous fl uid transfers energy to heat because of intrinsic friction. Bernoulli's principle states that the total energy of the fl uid is constant, but the friction yields an energy loss with a drop in energy along the line (E1 > E2 > E3). Therefore, the net change in kinetic and pressure energy is negative: ΔEc + ΔP = -ε. Owing to mass conservation and the stability of the tube diameter, the mass per unit time is stable, and there is no change in kinetic energy (Ec1 = Ec2 = Ec3). ( b ) As ΔEc + ΔP = -ε and ΔEc = 0, then ΔP = -ε, that is, a drop in pressure along the tube. The static pressure head, measured using a piezometer tube, is reduced along the line with P1 > P2 > P3. ( c ) A viscous fl uid is fl owing in a horizontal tube with local constriction. We know that E1 > E2 > E3. Where the tube is constricted, owing to mass conservation, the mass per unit of time is increased, i.e., increased velocity. At ➋ there is a local increase in kinetic energy (Ec1 < Ec2 > Ec3). ( d ) As ΔP = -ΔEc -ε, every increase in kinetic energy is associated with a greater inverse reduction in pressure. Ec1 < Ec2 > Ec3 yields P1 > P2 < P3 with a pressure drop at ➋. The static pressure head, measured using a piezometer tube, demonstrates the local pressure drop (P1 > P2 < P3)

Acknowledgments This paper is dedicated to Eric T. MacKenzie.

Confl ict of Interest Statement

No confl ict of interest to declare.