Supported Ionic Liquid Membranes Research Articles

Amine functionalized supported ionic liquid membranes (SILMs) for CO2/N2 separation

Supported ionic liquid membranes (SILMs), containing aprotic N-heterocyclic anion ionic liquids (AHA ILs) in an inorganic inert support, exhibit CO2/N2 permselectivity values as high as 640 at 35.0 °C and 0.03 bar CO2, which represents conditions similar to post-combustion carbon capture (PCCC) from a natural gas power plant. A Fickian model fit to the experimental data estimates CO2 permeability at direct air capture (DAC) conditions of 10,400 barrer and a CO2/N2 permselectivity of 4000 for the best performing IL, triethyl(octyl)phosphonium 4-bromopyrazolide ([P2228][4-BrPyra]). The most important criterion for high selectivity is a large equilibrium constant for binding between the IL and CO2, which results in high CO2 solubility. ILs with smaller molar volumes and with no fluoroalkyl chains enhance N2 rejection. Low viscosity and high IL molar density also enhance CO2/N2 permselectivity and CO2 permeance.

Stability and kinetic insights for ibuprofen removal from aquaculture wastewater using green supported ionic liquid membranes

Pharmaceutical residues in aquaculture effluent have become a growing environmental concern due to their potential ecological impacts. Supported ionic liquid membranes (SILM) offer a promising solution for extracting micropollutants from contaminated sources. SILM was developed using Aliquat 336 in sunflower oil (SFO) as a carrier solution, specifically targeting ibuprofen (IBP) in aquaculture wastewater. Different solid supports are fabricated through the nonsolvent-induced phase separation (NIPS) process and characterized by SEM, EDX, contact angle, FTIR and porosimeter. PVDF support is selected as solid support for immobilization of the carrier solution owing to its properties of having an asymmetrical shape, thickness of 48.8 µm, porosity of 72% and contact angle of 89.0° (feed side) and 85.3° (stripping side). The percentage of carrier loss obtained was only 1.10%. The optimal conditions for IBP removal were obtained at 0.50 M Aliquat 336, with a feed phase pH of 5.5 and stripping phase pH of 8. Further tests on real aquaculture wastewater affirmed the system’s efficacy in removing IBP and maintaining the stability at least the fifth cycle of membrane reusability. This study underscores the viability of proposed SILM system in mitigating IBP from aquaculture sector.

Supported Ionic Liquid Membrane with Highly-permeable Polyamide Armor by In Situ Interfacial Polymerization for Durable CO2 Separation.

Supported ionic liquid membranes (SILMs), owing to their capacities in harnessing physicochemical properties of ionic liquid for exceptional CO2 solubility, have emerged as a promising platform for CO2 extraction. Despite great achievements, existing SILMs suffer from poor structural and performance stability under high-pressure or long-term operations, significantly limiting their applications. Herein, a one-step and in situ interfacial polymerization strategy is proposed to elaborate a thin, mechanically-robust, and highly-permeable polyamide armor on the SILMs to effectively protect ionic liquid within porous supports, allowing for intensifying the overall stability of SILMs without compromising CO2 separation performance. The armored SILMs have a profound increase of breakthrough pressure by 105% compared to conventional counterparts without armor, and display high and stable operating pressure exceeding that of most SILMs previously reported. It is further demonstrated that the armored SILMs exhibit ultrahigh ideal CO2 /N2 selectivity of about 200 and excellent CO2 permeation of 78 barrers upon over 150h operation, as opposed to the full failure of CO2 separation performance within 36h using conventional SILMs. The design concept of armor provides a flexible and additional dimension in developing high-performance and durable SILMs, pushing the practical application of ionic liquids in separation processes.

Efficient removal of Cr (VI) from wastewater using recycled polymer-based supported ionic liquid membrane technology

Hexavalent chromium (Cr (VI)) is a hazardous form of chromium that poses a significant threat to human health and the environment. Meanwhile, Polyethylene Terephthalate (PET) bottles, despite their widespread use and practicality, contribute substantially to the plastic waste problem. Converting waste PET bottles into polymeric membranes offers significant promise. Supported ionic liquid membrane (SILM) technology is a relatively new technique that shows the potential to treat contaminated water efficiently. Experimental studies have demonstrated the influence of different operating conditions on Cr (VI) separation using SILM. The key parameters include concentrations of the feed phase, carrier (Aliquat 336), and strip phase (HCl) and their interactions. Around 98% of Cr (VI) can be removed at a feed concentration of 25 mg/l, a carrier concentration of 5%, and 0.5 M of HCl as a stripping agent. The optimal carrier concentration for membrane extraction was 5% (v/v), leading to a maximum removal rate of 98.34% at optimized values. To assess the impact of carrier concentration on the membrane, SEM-EDS mapping was done. The successful wastewater treatment from such an innovative approach enables handling plastic management and water pollution.

Enhancing CO2 separation from N2 mixtures using hydrophobic porous supports immobilized with tributyl-tetradecyl-phosphonium chloride [P44414][Cl

The main obstacles in adopting solvent-based CO2 capture technology from power plant flue gases at the industrial scale are the energy requirements for solvent regeneration and their toxicity. These challenges can be overcome using new green and more stable ionic liquids (ILs) as solvents for post-combustion CO2 capture. In the current study, tributyl-tetradecyl-phosphonium chloride [P44414][Cl] as an IL, was immobilized on hydrophobic porous supports of polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE) at 298 ± 3 K and pressures up to 2 bar. The surface morphology indicated homogenous immobilization of the IL on the membrane support. Supported ionic liquid membranes (SILMs) were tested for CO2 permeability and CO2/N2 selectivity. None of the SILMs exhibited IL leaching up to 2 bar. The PTFE-based SILM performed better than other supports with minimum loss in water contact angle (WCA) and achieved good antiwetting with a maximum CO2 permeability and selectivity over N2 of 2300 ± 139 Barrer and 31.60 ± 2.4, respectively. This work achieves CO2 permeability about two-fold more than other works having CO2/N2 selectivity range of 25–35 in similar SILMs. The diffusivity of CO2 and N2 in [P44414][Cl] was measured as 3.64 ± 0.18 and 2.01 ± 0.09 [10−8 cm2 s−1] and CO2 and N2 solubility values were 9.79 ± 0.47 and 0.19 ± 0.001 [10−2 cm3(STP) cm−3 cmHg−1], respectively. The high values of Young's modulus and tensile strength of the PTFE support-based SILM (234 ± 12 MPa and 6.07 ± 0.31 MPa, respectively) indicated the long-term application of SILM in flue gas separation. The results indicated phosphonium chloride-based ILs could be better solvent candidates for CO2 removal from large volumes of flue gases than amine-based ILs.

Stabilization of [BMIM][PF6] ionic liquid membrane in structurally optimized multilayer ceramic support through aqueous DEA solution for CO2/CH4 separation

The stability of the ceramic supported liquid membranes (SLMs) is one of the most interesting research subjects. In this work, the SLMs’ stability for CO2/CH4 separation was investigated. Following pressing α-Al2O3 substrates at 400, 600, and 800 bar, colloidal and polymeric TiO2 intermediate and top layers were coated. Aqueous diethanolamine (DEA) solution was used as solvent in the SLM to optimize support structure based on CO2/CH4 separation performance. The pressed support at 800 bar and coated with TiO2 demonstrated best performance and selected for further study. Subsequently, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) ionic liquid (IL) was immobilized inside the selected support and used as the supported ionic liquid membrane (SILM) for CO2/CH4 separation. The SILM separation performance was evaluated under different pressures and temperatures. Temperature was found to has greater effect than pressure due to a decrease in IL's viscosity and an increase in penetrant diffusivity. At 25 °C and 1 bar, SILM exhibited consistent and reliable performance as CO2 and CH4 permeabilities of 244.0 and 7.4 Barrer, respectively, and CO2/CH4 selectivity of 33.0 over 6 h. The findings contribute to understanding the implementation of multilayer ceramic SILMs for CO2/CH4 separation and highlight its potential along with opening up new avenues.

Theoretical study of supported ionic liquid membrane reaction and transport for CO2 cycloaddition reaction

Membrane reactors are promising for achieving a variety of thermodynamically limited reactions. However, few studies have focused on quantitative analysis of the coupling of reaction and separation matching of membranes. In this work, based on the experimental validation of the forced flow through principle of membrane reactors for catalytic CO2 cycloaddition, describes the membrane reaction performance of supported ionic liquid membranes (SILMs) in the presence of primary irreversible reactions, and draws on a dusty gas model to calculate fluxes within the gas pore space of the support. The degree of product separation is theoretically investigated in relation to the membrane permeation, the resistance difference between the ionic liquid membrane and the support, the liquid loading of the catalyst layer and the fluid flow rate, and adjustable parameters of the model are proposed to predict the SILM performance. In addition, two dimensionless numbers, namely Damköhler (Da) and Péclet (Pe) numbers, are introduced to correlate the equilibrium constant-conversion-DaPe relationship, and the reaction kinetics and permeate flux compatibility are analyzed with the help of CFD simulations, which incorporate parameters of operating conditions and stoichiometric coefficients of the reaction, as well as optimization of reactor geometrical, providing insights to achieve higher conversion improvements.

Removal of low concentration ibuprofen using green diluent and novel formulated supported ionic liquid membrane

Removal of pharmaceutical micropollutants is critical to reduce detrimental contaminants found in the environment. The current study focuses on developing a new formulation of supported ionic liquid membrane (SILM) for removing low concentration of ibuprofen (IBP) using green diluent and ionic liquid. Parameters such as solid support properties, variation of diluents, type of carrier and carrier concentration are investigated. The results demonstrate that liquid carrier consisted of sunflower oil (SFO) and Aliquat 336 successfully impregnated on the PVDF support via FTIR and SEM analysis. Liquid carrier loss from the PVDF support is less than 1% by impregnating green diluents consisting of SFO. 18PVDF-DMAC/300 is selected owing to its asymmetric finger-like and spongy structure with porosity, mean pore diameter, contact angle and thickness of (82.2 ± 0.7) %, (0.19 ± 0.01) μm, (89.4 ± 0.2)° and (90.3 ± 0.8) μm, respectively. Under 72-hour operation, a maximum extraction and stripping efficiency are obtained at 93% and 87% respectively, indicating a stable SILM process. Results obtained suggest that the newly formulated SILM is advantageous and may be used to extract low concentrations of IBP from the feed phase.

Novel-supported ionic liquid membranes for an effective removal of pentachlorophenol from wastewater

Recently ionic liquids (ILs) have been useful in many areas of wastewater treatment and separation processes in environmental engineering, such as supported ionic liquid membranes (SILM) based separations and solvent extraction applications. In this work novel ILs, namely 1-butyl-2,3-dimethyl imidazolium hexafluorophosphate [C4DMIM][PF6], tetrabutyl–phosphonium exafluorophosphate [TBP][PF6] were immobilized on PVDF (polyvinylidene fluoride) membrane for the removal of organic pollutant such as pentachlorophenol (PCP) from the water phase by SILM. Operating conditions like pH, feed and permeate concentration, membrane flux, and the mechanism was also studied. The interactions of H+ bonding, hydrophobic interactions, and carbon–π bonding interactions are explained via the SILM transport mechanism. The membranes were characterized by SEM, EDX, and FTIR analysis. In the experimental study, a high zetapotential of −93.24 mV was achieved, which is an indication of the excellent stability of SILM. At a pH of 4, [TBP][PF6] had the highest penetration rate of 87%. In contrast, [C4DMIM][PF6] yielded 79% after 30 h of experimentation at the feed pH 4. Similarly, after 30 h, [TBP][PF6] got the highest rate of permeation (80.50%), followed by [C4DMIM][PF6] (73.00%). The 0.1 M NaOH was used as a stripping agent in this study. PCP was successfully separated from the aqueous phase using two different hydrophobic ionic liquids as [C4DMIM][PF6] and [TBP][PF6]. This SILM technique has the potential in the future for further developments and for extracting organic contaminants from wastewater on a laboratory or industrial scale.

Current status of CO2 capture with ionic liquids: Development and progress

Global warming triggered by greenhouse gas (GHG) emissions, particularly carbon dioxide (CO2), significantly influences climate change and has become a common environmental issue recently. The current amine-based technologies (ABTs) for CO2 capture (CAPCO2) have high energy demand, low absorption, and desorption rates, and are less environmentally sustainable due to high emissions of volatile solvents. Therefore, the development of environmentally friendly CAPCO2 materials and/or processes is a growing area of research. The utilization of ionic liquids (ILs) for CAPCO2 has recently attracted attention. The unique characteristics of ILs, such as their low vapor pressure and high affinity for CAPCO2 as well as their low volatility make them a viable substitute for the existing processes. This work provides a comprehensive overview of the accomplishments and challenges during the use of ILs for CAPCO2. The Review also outlines the mechanisms of the CAPCO2 with ILs at the molecular level, the properties of ILs, characterization of the CO2/IL systems, and the effect of operating conditions on CO2 uptake (UPCO2) capacity by ILs. It also emphasizes the impact of cations, anions, and functional groups on the solubility of CO2 ((SCO2)) in ILs as well as the biodegradability and toxicity of ILs. Additionally, recent advances in IL membrane technology for the CAPCO2 processes are considered. Lastly, the contribution of molecular simulations to create and assess ILs was reviewed. Protic and aprotic ILs properties have shown outstanding efficiency of UPCO2. The interactions between the anionic part of IL and CO2 enhance the UPCO2 and outperform the efficiency of traditional organic solvents. Functionalized ionic liquids (FUNILs) with tuned functional groups, supported ionic liquids membranes (SILMs) as well as reversible ionic liquids (RILs) have improved the efficiency of ILs as a promising CO2 capturing process from industrial streams even under low CO2 partial pressure. The relative importance of the chemical breakdown of the IL constituents (cation–anion interfacial structuring) during the CAPCO2 process at different operating temperatures is unclear, and more research in this area is required to better inform the design of new ILs. This review provides a proper/systematic guideline to help ILs manufacturers and engineers design high-capacity ILs for appropriate CAPCO2.

Performance Evaluation of Supported Ionic Liquid Membranes (SILMs) Derived from Optimized PES/PDMS/ZIF-L Composites for CO2 Separation

Performance Evaluation of Supported Ionic Liquid Membranes (SILMs) Derived from Optimized PES/PDMS/ZIF-L Composites for CO₂ Separation

Evaluation of task-specific ionic liquids applied in pervaporation membranes: Experimental and COSMO-RS studies

The production of dimethyl carbonate (DMC) from CO2 and methanol (MeOH) is an attractive route for CO2 capture and utilization. In this process, the separation of DMC from the reaction medium is critical to maximize the conversion of CO2. However, DMC and MeOH form an azeotropic mixture that is difficult to separate. This work investigates the possibility of using task-specific ionic liquids (TSILs) in the form of supported ionic liquid membranes (SILMs) to separate and purify DMC by using pervaporation. Two tertiary amine ILs, i.e., 1-octyl-3-methylimidazolium bromide ([Omim][Br]) and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Omim][NTf2]), and one cyclic quaternary ionic liquid, i.e., 1-octyl-1,4-diazabicyclo[2.2.2]octanium bromide ([ODABCO][Br]), were prepared. The structure and purity of the synthesized ILs were confirmed by NMR and FTIR, and the as-synthesized ILs along with one commercial quaternary ammonium IL, tetrabutylammonium bromide ([TBA][Br]), were further characterized using TGA/DSC. SEM-EDX, tensile tests and stability tests were also performed to characterize the SILMs. During the pervaporation experiments, the SILMs showed an initial decrease in DMC and MeOH permeance over time, followed by a gradual stabilization, with a relatively stable DMC/MeOH selectivity as pure liquids. In addition, an increase in temperature is shown to have negative effect on DMC and MeOH permeance because sorption, which is an exothermic process, governed the transport of molecules across the membrane. The studied SILMs exhibited higher selectivity at low temperatures, especially at 30 °C. Furthermore, the COSMO-RS model provided insights of the effect of IL structures on the separation of DMC from MeOH at molecular level.

Ionic Liquid Mixtures for Direct Air Capture: High CO2 Permeation Driven by Superior CO2 Absorption with Lower Absolute Enthalpy.

This paper reports a series of liquid materials suitable for use as high-performance separation membranes in direct air capture. Upon mixing two ionic liquids (ILs), namely N-(2-aminoethyl)ethanolamine-based IL ([AEEA][X]) and 1-ethyl-3-methylimidazolium acetate ([emim][AcO]), the resulting mixtures with a specific range of their composition showed higher CO2 absorption rates, larger CO2 solubilities, and lower absolute enthalpies of CO2 absorption compared to those of single ILs. NMR spectroscopy of the IL mixture after exposure to 13CO2 allowed elucidation of the chemisorbed species, wherein [AEEA][X] reacts with CO2 to form CO2-[AEEA]+ complexes stabilized by hydrogen bonding with acetate anions. Supported IL membranes composed of [AEEA][X]/[emim][AcO] mixtures were then fabricated, and the membrane with a suitable mixing ratio showed a CO2 permeability of 25,983 Barrer and a CO2/N2 selectivity of 10,059 at 313.2 K and an applied CO2 partial pressure of 40 Pa without water vapor. These values are higher than those reported for known facilitated transport membranes.

Synthesis and performance evaluation of copper and magnesium-based metal organic framework supported ionic liquid membrane for CO2/N2 separation

The CO2 emission is enhancing drastically because of the continuous emission from industries and transport sector. Although the CO2 emission had decreased in the first half of 2020 by 8.8% due to COVID-19 restrictions however, it is again on the rise and it might exceed the estimated level in 2030. The current methods used for CO2 separation have serious operational and environmental constraints. To overcome these problems we have devised a supported ionic liquid membrane (SILM) incorporated with the blend of bimetallic metal-organic framework (MOF) of copper and magnesium ions (CuxMgx) and Trihexyltetradecylphosphonium chloride [P66614] [Cl] ionic liquid (IL). CuxMgx MOF were synthesized and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and energy dispersive X-ray analysis (EDX). CuxMgx MOF with [P66614] [Cl] IL were immobilized on a flat sheet of polytetrafluoroethylene (PTFE) membrane. Single gas permeation tests of membranes loaded with 0.2/0.8 wt/wt% MOF/IL solution showed the highest CO2 permeability of 2937 Barrer and CO2/N2 selectivity of 33.26. The performance of SILM was also investigated with different water loadings of (30 wt % and 50 wt %) in addition to MOF/IL solution and at different feed pressure varying from 0.5 to 2 bars. Membranes showed enhancement in CO2 permeability to 3738 and 4628 Barrer whereas CO2/N2 selectivity decreased to 23.53 and 21.8 with membranes loaded with 30 and 50 wt % water, respectively, at a feed pressure of 2 bar. The gas permeation results show that the incorporation of CuxMgx MOF with IL in polymeric membrane enhances the CO2/N2 separation under humid conditions but slightly decreases CO2/N2 selectivity with an increase in feed pressure. The SILM synthesized in this research is highly viable for industrial flue gases because of the incorporation of phosphonium-based ILs that have high thermal stability.

Ordered mesoporous silica matrices supported ionic liquids for efficient CO2 separation from CO2/CH4 gas mixture: Experimental and theoretical investigation

Global concern over CO2 reduction to avoid global warming has escalated due to alarming CO2 concentrations in the atmosphere. In this connection, supported-ionic liquids (SILs) have been prepared by physically imbibition of 1-ethyl-3-methylimidazolium tetrafluoroborate (C2mim BF4) ionic liquid (IL) into ordered mesoporous silica (MS) matrices to design SILs-membranes (SILMs) for gas separation technology. These SILs were characterized by powder XRD, 29Si NMR, SEM, FTIR, and 1H NMR spectroscopy, N2 sorption, and TGA analyses. FTIR study reveals that vibrational frequencies related to C2mim+ cation ring remain unchanged upon confinement of nanopores of MS whereas Si-O-Si band, Si-O band, and anion band shifted indicating IL interacting with the MS surfaces. Density functional theory (DFT) calculations also explore the structural features of these SILs. SILMs based on Pebax-1657 were also designed using a solution casting technique to evaluate their gas separation performance and characterized using XRD and SEM techniques. C2mimBF4/MCM-48 membrane exhibit higher permeability for CO2 both in single and mixed gas studies. These results were further supported by DFT analysis in terms of complexation energies (Ec) which demonstrates the strong affinity of these SILs membranes towards CO2 and CH4 gases, respectively. Further, a nice correlation was established between the experimental and theoretical findings.

A novel supported ionic liquid membrane reactor for catalytic CO2 conversion

Converting CO2 into cyclic carbonates is one of the most promising ways to help mitigate global climate change. In this paper, we developed a novel supported ionic liquid membrane (SILM) that integrates reaction and gas permeation functions into a single unit for efficient synthesis of propylene carbonate (PC) under solvent-free, cocatalyst-free, and catalyst-free separation conditions. The catalytic stability of SILM was verified by batch experiments, and the structure, morphology and composition were characterized by XRD, SEM, and EDS. Also, the process parameters of continuous membrane catalysis were evaluated for PO conversion, PC selectivity, space-time yield and PO flux. By comparative analysis, polyvinylpyrrolidone (PVP) could not only effectively inhibit the loss of ionic liquid (IL), but also help to form a stable membrane layer. Characterization results confirmed that IL was basically concentrated in the top layer of γ-Al2O3 rather than the intermediate layer. Besides, the essential factors were identified to provide a feasible route for the large-scale conversion of CO2.

Molecular simulation study on CO2 separation performance of GO/ionic liquid membrane

The supported ionic liquid membrane (SILM) has advanced to a promising solution for CO2 capture. It has been extensively studied owing to its high efficiency and complexity. Here, we showed that various heterogeneities, such as ionic liquid (IL) loading and pore size, are likely to affect CO2 transport and separation behavior within the SILMs by molecular dynamics simulation. Our results reported that the intra-membrane further controls the gas selectivity and permeability mainly through its effect on the compactness of the gas-liquid interface and the free volume within the membrane. Additionally, compared with a wide-pore monolayer, the confined space effect of a narrow-pore bilayer is more significant, and the influence of the deformation (flexibility and rigidity) on separation is weakened. This study highlighted the effect of structural heterogeneity on gas separation at a molecular level, which might facilitate the development of 2D-materials.

Recent Advances in Supported Ionic Liquid Membrane Technology in Gas/Organic Compounds Separations

Abstract: The development of the convenient separation processes is a major challenge being examined by scientists and technologists due to its industrial applications. The supported liquid membrane (SLM) technology has been widely employed to separate several species, like permeable gas from binary gaseous mixtures, metal ions, and organic and biological compounds. The main reason for the limited use of SLMs in the industry is their short life and less stability due to the high volatility of traditional organic solvents. Room-temperature ionic liquids (RTILs) are environmentally benign designer salts, exhibit negligible volatility, show good thermal stability, and have remarkable solubility, thus, acting as an alternative solvent to overcome the drawbacks of SLMs. Besides, the high viscosity of ionic liquids (ILs) offers good capillary force, which prevents their flow into membrane pores even under high pressure. Moreover, their tuned properties make them amenable compounds for their immobilization into membrane pores to provide supported ionic liquid membranes (SILMs) with good mechanical strength. In literature (from 2007 to the present), a variety of SILMs have been designed, synthesized, and employed in the field of separation science. This review is mainly focused on the applications of SILMs in the separation of more permeable gases (CO2, O2, CO, H2, and C2H4) from binary gas mixtures as well as the separation of organic compounds (organic acids, alcohols, aromatic hydrocarbons, amines, reactants and products of transesterification reaction, nitrogen- and sulfur-containing aromatic compounds) from distinct mixtures.

A reduced pressure-assisted vapor penetration of ionic liquid into the laminated graphene oxide membranes for efficient CO2 separation

Tailor-made ultrathin and defect-free supported ionic liquid membranes (SILMs) have great potential for CO2 separation. Herein, we developed a highly perm-selective CO2-philic laminated GO supported ionic liquid membrane (GO-SILM) with a thickness of 100 nm, via a reduced pressure-assisted vapor penetration strategy. Specifically, under reduced pressure condition, the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) vapor can not only seal the possible defects/pores in GO membrane, but also penetrate into the 2D nanochannels of laminated GO membrane. Based on the favorable interaction between IL and GO nanosheets, IL can be confined within the nanochannels of laminated GO membranes, which favors a fast and selective CO2 transport. Besides, the ultrathin selective layer shortens the transport distance extremely. Benefiting from the aforementioned features, the obtained GO-SILMs display a high CO2 permeance of 56.6 GPU with CO2/CH4 selectivity of 53.5, which is superior to other reported SILMs. The groundbreaking membrane fabrication approach through reduced pressure-assisted IL vapor penetration into GO membrane to seal the non-selective defects is facile, effective and IL-saving, which paves a new way for the development of ultrathin and defect-free SILMs for high-efficient CO2 separation.

Tunning CO2 Separation Performance of Ionic Liquids through Asymmetric Anions.

This work aims to explore the gas permeation performance of two newly-designed ionic liquids, [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2], in supported ionic liquid membranes (SILM) configuration, as another effort to provide an overall insight on the gas permeation performance of functionalized-ionic liquids with the [C2mim]+ cation. [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] single gas separation performance towards CO2, N2, and CH4 at T = 293 K and T = 308 K were measured using the time-lag method. Assessing the CO2 permeation results, [C2mim][CF3BF3] showed an undermined value of 710 Barrer at 293.15 K and 1 bar of feed pressure when compared to [C2mim][BF4], whereas for the [C2mim][CF3SO2C(CN)2] IL an unexpected CO2 permeability of 1095 Barrer was attained at the same experimental conditions, overcoming the results for the remaining ILs used for comparison. The prepared membranes exhibited diverse permselectivities, varying from 16.9 to 22.2 for CO2/CH4 and 37.0 to 44.4 for CO2/N2 gas pairs. The thermophysical properties of the [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] ILs were also determined in the range of T = 293.15 K up to T = 353.15 K at atmospheric pressure and compared with those for other ILs with the same cation and anion’s with similar chemical moieties.