Metal-organic framework (MOF) membranes with high stability and porosity have shown great potential for efficient hydrogen separation. As a result, searching for a simple and efficient synthesis method to synthesize large-area, continuous, and dense MOF membrane has received an extensive attention. In this work, we demonstrated a support-induced synthesis strategy to fabricate a series of 20-cm long bimetallic Zn/Co-ZIF membranes on the inner surface of ZnO hollow fiber. Uniform-thickness Zn/Co-ZIF membranes were prepared by periodically inverting the autoclave to alter the flow state of the synthesis solution inside the hollow fibers. The obtained Zn/Co-ZIF membrane showed a good H2/CH4 selectivity of 15.75 with an H2 permeance of 1.15 x 10-7mol.m-2.s-1.Pa-1 and the membrane displayed excellent long-term operation stability for 20 days. Furthermore, eleven Zn/Co-ZIF membranes (with a membrane area of up to about 100.91 cm2) were successfully prepared in an autoclave to further improve the metal source utility. These membranes exhibited similar H2 separation performance, with H2/CH4 selectivities of 12.69-14.59 and H2 permeances of 1.64-2.05 x 10-7 mol.m-2.s-1.Pa-1, demonstrating excellent reproducibility.

Pore wetting is one of the key factors blocking the development of membrane distillation (MD). This study aimed to develop a wetting model and an equilibrium equation of the gas/liquid interface for membranes in direct-contact MD (DCMD). The model was verified by experimental results and correlated with the membrane porous structure, feed flow rate/hydraulic pressure, and feed temperatures. It was found that reducing membrane pore size had a greater impact in maintaining the gas/liquid interfacial stability rather than controlling the surface hydrophobicity. Furthermore, pore wetting caused by membrane fouling from surfactant adsorption and calcium sulfate deposition can be reduced via membrane cleaning to restore its original hydrophobicity. DCMD operation at low feed pressure could inhibit membrane wetting, particularly operation at negative pressure, which greatly improved the flux stability when liquid with a low surface tension was used as a feed. Other factors like feed pressure and membrane configurations were also discussed for their effects in pore wetting.

Despite the growing interest in porous liquids, their potential for membrane-based liquid separations remains largely unexplored. Herein, we report an anion-encapsulated type III porous liquid developed by homogeneously dispersing ZIF-8 in the ionic liquid trihexyltetradecylphosphonium chloride ([P6,6,6,14][Cl]). Both experimental and computational studies confirm that the resulting ZIF-8/[P6,6,6,14][Cl] system exhibits high fluidity at room temperature due to the enhanced mobility of chloride ions within the ZIF-8 framework. When used as a selective component for the separation of challenging mixtures such as dimethyl carbonate and methanol, the membrane exhibits superior performance, with significantly higher selectivity and an order of magnitude higher permeance of dimethyl carbonate compared to previously reported membranes. This enhanced separation capability is attributed to the unique liquid properties of the porous liquid and the selective adsorption affinity of ZIF-8. These results highlight the promising role of type III porous liquids in facilitating efficient membrane separations.

The need for sustainable and carbon-neutral technologies is growing due to ambitious climate goals and the depletion of non-renewable resources. Carbon capture and utilization (CCU) is emerging as a key approach to closing the carbon cycle, with membrane-based CO2 absorption reducing energy demands during the capture process. However, conventional membranes rely on fossil-based polymers and toxic solvents, raising concerns about their environmental impact. This study introduces a bio-based membrane contactor for CCU applications, utilizing polylactic acid (PLA), a renewable and sustainable biopolymer. The influence of polymer concentration, molecular weight, crystallinity, solvent type, and recycling on membrane morphology and CO2 capture performance was investigated. The PLA membranes exhibited asymmetric morphologies ranging from finger-like to sponge-like structures. Higher polymer concentration and molecular weight increased sponge-like morphology, while solvents with stronger solvating power promoted finger-like structures. Interestingly, initial polymer crystallinity did not influence membrane morphology, but crystallinity induced during synthesis supported sponge-like structures. Membranes made with high molecular weight PLA and wide finger-like morphologies demonstrated stable CO2 capture performance (2.36 × 10-⁵ m³/m²·s), comparable to commercial PVDF membranes (2.47 × 10-⁵ m³/m²·s). Furthermore, recycled membranes retained CO2 capture performance over five cycles (2.04 – 2.26 × 10-⁵ m³/m²·s). This study highlights the potential of bio-based membranes to enable energy-efficient and circular CO2 capture, taking significant steps toward greener, more sustainable CCU technologies.

Two-dimensional membranes composed of nanosheets can significantly reduce mass transport resistance and improve separation or rejection performance of molecules or ions given their regular sub-nano channels and robust chemical adaptability. This review focuses on the recent development in two-dimensional membrane for ion and/or molecule separation in water treatment, delving into the preparation of nanosheets, the recent advances of horizontal and vertical channeled lamellar membranes and their separation mechanisms. For the very thin horizontal channeled lamellar membranes (H-CLMs) that surpass the trade-off limitation, the assembly methods mainly include vacuum-assisted filtration, layer-by-layer assembly, and coating. Furthermore, modification methods during pre- and post-membrane fabrication are summarized in detail. Based on the ions/molecules transport through sub-nano channels, the filtration, the conductive membrane, and the pervaporation applications of H-CLMs are discussed. Specifically, the advanced vertical-channeled laminar membranes (VCLMs) featuring short and straight transport paths, were comprehensively discussed for the first time in terms of the assembly, the modification, and the application. The different mass transport mechanisms of these twodimensional membranes, i.e., size sieving, electrostatic interactions, and chemical bonding effects were elaborated given their importance in designing advanced membrane materials and enhancing separation performance. Finally, the challenges and outlooks of two-dimensional membranes were given in new membrane materials, assembly technology of V-CLMs, sub-nano channel tailoring, and long-term performance.

The enzyme carbonic anhydrase (CA) has gainned considerable attention from the literature and the industry in the context of CO2 capture. CA immobilization in gas-liquid membrane contactors, and more specifically, on poly(ionic liquid) (PIL) composite membranes has been demonstrated to be a potential strategy to facilitate its industrial implementation. These membranes were comprised of a PIL layer coating on a porous hydrophobic polymeric support. In this work, the composition of the PIL layer was tuned by anion exchange to yield a variety of enzyme carriers. The following anions were compared: bromide [Br], acetate [Ac], tetrafluoroborate [BF4], and bis(trifluoromethylsulfonyl)imide [NTf2]. The surface morphology, chemistry, and properties of these composite membranes were characterized by SEM, EDX, ATR-FTIR, and water contact angle. The activity of the different biocatalytic composite membranes was determined by the p-nitrophenyl acetate hydrolysis model reaction. It was found that the anion exchange salts had a detrimental effect on the immobilized enzyme activity. In light of these results, the enzyme immobilization step was conducted after anion exchange. The resulting biocatalytic membranes displayed slight differences in immobilized enzyme activities and thermal stabilities following the order [Br]>[BF4]>[Ac]>[NTf2] and [BF4]>[Br]≈[Ac]>[NTf2], respectively. The differences were more pronounced and detrimental for the most hydrophobic anion, [NTf2]. Parallel trends were noted when the membranes were tested for CO2 absorption in a gas-liquid membrane contactor set-up suggesting that the CO2 mass transfer is strongly influenced by the activity of the immobilized enzymes. In addition, the effect of the absorption conditions, i.e., solvent flow rate, solvent saturation, and solvent concentration were evaluated. Under the best conditions, the novel biocatalytic membranes outperformed the commercial PVDF support by about a factor of 4 in terms of overall mass transfer coefficient. Such improvement would result in significant reductions in the required membrane area to capture CO2 by a gas-liquid membrane contactor.

Chitosan, as the second most abundant biopolymer on earth, is constantly increasing attention from different fileds such as biomedicals, food, energy, and the environment. However, its application in membrane technology such as pervaporation is lacking of an effective membrane manufacture strategy to improve its separation efficiency. Herein, we use a chitosan-based membrane subjected to neutralization and crosslinking procedures in contrasting solvents—specifically, water and ethanol—to explore the impact of polymer-solvent interactions on the effective nanogaps between polymer nanofibers. Under identical conditions, the procedures conducted in water yield hydrated membranes, while those in ethanol resulted in anhydrous membranes. In hydrated membranes, strong hydrogen bonds formed between water and amine groups block nanogaps amongst polymer nanofibers, significantly impeding molecular transport. Conversely, the absence of such strong hydrogen bonds in anhydrous membrane avoided this effect. This study highlights the potential of controlling the transport of organic molecules by tuning the nanogaps within the membrane matrix. This was achieved through a novel strategy involving washing the chitosan-based membranes with pure ethanol to remove free acids, followed by direct crosslinking in a glutaraldehyde ethanol solution. This strategy was able to double the membrane selectivity despite a 25% reduction in methanol permeance.

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-3methylimidazolium 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 degrees C. Furthermore, the COSMO-RS model provided insights of the effect of IL structures on the separation of DMC from MeOH at molecular level.

Metal–organic frameworks (MOFs), a sub-group of porous crystalline materials, have been receiving increasing attention for gas separation and pervaporation because of their high thermal and chemical stability, narrow window sizes, as well as tuneable structural, physical, and chemical properties. In this review, we comprehensively discuss developments in the formation of continuous MOF membranes for gas separation and pervaporation. Additionally, the application performance of continuous MOF membranes in gas separation and pervaporation are analysed. Lastly, some perspectives for the future application of continuous MOF membranes for gas separation and pervaporation are given.

Ionic liquid (IL) has gained attention in the development of highly permeable and selective gas separation membranes due to its unique physicochemical properties. The many possible combinations of cations and anions, chemical structures and immobilization techniques make IL a promising candidate to overcome the current problems in gas separation membranes. This chapter reviews the physicochemical properties and classification of IL followed by different configurations of ionic liquid-based gas separation membranes and their gas separation performance. Finally, a perspective is provided to help address the current challenges of applying IL as a practical material in preparing gas separation membranes.

Most cellulose triacetate (CTA)-based studies for forward osmosis (FO) have greatly focused on achieving asymmetric membranes with a highly porous sublayer along with a dense selective layer. Such membranes can achieve better fluxes due to improved mass transfer and reduced internal concentration polarization. In this work, patterning of the CTA-membranes via modification of the conventional non-solvent induced phase inversion is explored as an alternative mute to increase FO water flux without reducing salt selectivity. The modified way of applying the non-solvent in this method increased the membrane bulk porosity from similar to 17 % to similar to 50 %. Such high porosity and reduced tortuosity of the patterned membrane can reduce the internal concentration polarization by back-transport and reduced accumulation of salt and other solutes in the porous support. During FO, the patterned CTA membrane showed a water flux of 30 L m(-2) h(-1) and reverse salt flux of 25 g m(-2) h(-1), thanks to the increased effective membrane area, low water transport resistance, and high porosity of the membrane support. The patterned CTA-membranes may have potential in FO for applications with larger draw solutes due to the slightly larger pores on the membrane surface following the non-solvent spraying. Alternatively, some phase inversion parameters can still be further tuned to lower the salt passage.

Pervaporation competes with conventional separation techniques, such as distillation and adsorption in organic liquid dehydration, removal or recovery of organic compounds from aqueous solutions, and separation of organic-organic mixtures. Pervaporation is a separation technique relying on the concentration gradient, often expressed as partial vapor pressures, across polymeric or polymer-composite membranes. Those membranes often exhibit a strong trade-off between permeability and selectivity of target compounds, making the search for alternative materials with advanced performance characteristics highly desirable. Metal-organic frameworks (MOFs), a sub-group of porous functionalised materials, have recently demonstrated potential to become a valuable building block in the fabrication of future high-performance pervaporation membranes. MOFs feature unique properties, such as molecular sieve effects, preferential adsorption to the target molecular compounds, and thermal and chemical stability, being suitable for direct applications in pervaporation separation of liquid mixtures. This paper comprehensively examines the current design strategies of MOF-based membranes in pervaporation. The main developments of MOF-based membranes in pervaporation are discussed and the performance of pervaporation processes using MOF-based membranes is also analysed. Furthermore, some perspectives for future development of MOF-based membranes in pervaporation are given.

The development of pervaporation desalination has seen continuous interest due to the ability of this technology to handle high salinity feeds in the absence of high hydraulic pressure. As pervaporation utilizes the difference of partial vapor pressure as the main driving force for separation, an elevated feed temperature is often needed, and this significantly increases the energy requirements of pervaporation desalination. The advancement of high-performance pervaporation desalination membranes with high water flux and salt rejection in recent years could make this desalination technology competitive to other hypersaline desalination processes. Unfortunately, there is a lack of understanding of the energy requirements necessary for an economic assessment of pervaporation desalination applied for highly saline feed solutions. In this study, the energy requirements and the economic feasibility of pervaporation desalination for hypersaline desalination were evaluated using previously developed high-performance cellulose triacetate/cellulose nanocrystals nanocomposite membranes as the membrane model. The results showed that thermal energy was still the main factor that determined the overall water production cost. Increasing the plant capacity decreased the water cost while increasing the feed salinity from 90 to 200 g L-1 increased the water production cost due to the drop of the water production rate, which requires to expand the membrane surface area to obtain the same plant capacity. A series configuration showed the lowest thermal energy compared to a single and parallel configuration. However, the single configuration is more attractive than a series and parallel configuration when the pervaporation desalination utilized free low-grade waste heat. Hence, PV desalination for treating hypersaline water can be competitive if the process could be integrated with low-grade waste heat from industrial plants as a thermal energy source.

Crosslinked polyimide membranes were applied in solvent-resistant nanofiltration (SRNF) for separations in apolar solvents at elevated temperatures up to 80°C. The crosslinked membranes were prepared via a simplified method, combining phase inversion and aliphatic diamine crosslinking. By simply tuning the polymer casting concentration and the solvent/co-solvent ratio, tight SRNF membranes were obtained with a molecular weight cut-off (MWCO) of <450 g/mol during operation at temperatures up to 80 °C. Anisole and Sudan Black B (456 Da) were used as model non-polar solvent and solute, respectively.Membranes prepared with THF concentrations in NMP between 45 and 60 wt.% and 2 min evaporation before immersion in a DI water bath containing 2.0 wt.% HDA had rejections of > 90%. The membrane prepared with an equal amount of NMP and THF exhibited the highest permeance.Remarkably, solvent activation of the membrane prior to use turned out to be depending on the type of final solvent used in the filtration. Membranes activated with ethyl acetate gave the best performance when applied in anisole; ethanol activated membranes gave the best performance when applied in toluene and DMF for use in heptane.

The separation of dimethyl carbonate (DMC) -an ecofriendly organic compound- from a reaction medium is oftentimes complicated due to the presence of other organic compounds, particularly when the mixture forms an azeotrope. To this end, pervaporation is proposed in this work as the perfect candidate to solve this separation puzzle, using novel membranes which flipped the ratio of the binary mixture methanol (MeOH) and DMC (from 10:90 to ~90:10). ZIF-8 fillers were incorporated into chitosan (CS) biopolymer matrix to prepare these mixed matrix membranes (MMM). At 15 wt% loading of ZIF-8/CS, the~30 mu m-thick MMM showed an exceptional selectivity of 11.2, with MeOH permeance of 97.7 GPU at 50 celcius. This superior separation performance is attributed to the higher MeOH affinity to the CS matrix, further reinforced with the preferential channels of ZIF-8 fillers for MeOH. This successful separation of binary organic mixtures elevates a crucial part of downstream processing, merely achieved with conventional distillation, and most importantly, open doors to greener fuels.

Organic solvent nanofiltration (OSN) is gradually expanding from academic research to industrial implementation. The need for membranes with low and sharp molecular weight cutoffs that are able to operate under aggressive OSN conditions is increasing. However, the lack of comparable and uniform performance data frustrates the screening and membrane selection for processes. Here, a collaboration is presented between several academic and industrial partners analyzing the separation performance of 10 different membranes using three model process mixtures. Membrane materials range from classic polymeric and thin film composites (TFCs) to hybrid ceramic types. The model solutions were chosen to mimic cases relevant to today's industrial use: relatively low molar mass solutes (330-550 Da) in n-heptane, toluene, and anisole.

A series of cellulose triacetate/Ludox-silica nancomposite pervaporation membranes was successfully prepared via solution casting, aiming to improve the performance of cellulose triacetate membranes for desalination. The fabricated nanocomposite membranes were characterized to study the membrane morphology, chemical composition, mechanical properties, and surface hydrophilicity. Furthermore, the desalination performance was investigated as a function of silica (SiO2) loading (ranging from 1 to 4 wt%) and feed concentration at 30 and 60 g/L of sodium chloride (NaCl). Pervaporation experiments showed that incorporating 4 wt% SiO(2)into a cellulose triacetate (CTA) membrane increased the water flux by a factor 2.5 compared with pristine CTA (from 2.2 to 6.1 kg m(-2)h(-1)) for a 30 g/L NaCl feed solution at 70 degrees C, while the salt rejection remained above 99%. The CTA/4 wt% SiO(2)membrane was found to have only 21% flux reduction when tested with a 60 g/L NaCl feed solution, without changes in membrane selectivity. This suggests that the developed CTA/Ludox-SiO(2)nanocomposite pervaporation membrane is suitable for desalination.

The emergence and accumulation of microplastics (MPs) in various aquatic environments have recently raised significant concerns. Wastewater treatment plants (WWTPs) have been identified as one of the major sources of MPs discharge to the environment, implying a substantial need to improve advanced techniques for more efficient removal of MPs. Polymeric membranes have been proven effective in MPs removal. However, fouling is the main drawback of membrane processes and MPs can foul the membranes due to their small size and specific surface properties. Hence, it is important to investigate the impacts of MPs on membrane fouling to develop efficient membrane-based techniques for MPs removal. Although membrane technologies have a high potential for MPs removal, the interaction of MPs with membranes and their fouling effects have not been critically reviewed. The purpose of this paper is to provide a state-of-the-art review of MPs interaction with membranes and facilitate a better understanding of the relevant limitations and prospects of the membrane technologies. The first section of this paper is dedicated to a review of recent studies on MPs occurrence in WWTPs aiming to determine the most frequent MPs. This is followed by a summary of recent studies on MPs removal using membranes and discussions on the impact of MPs on membrane fouling and other probable issues (abrasion, concentration polarisation, biofouling, etc.). Finally, some recommendations for further research in this area are highlighted. This study serves as a valuable reference for future research on the development of anti-fouling membranes considering these new emerging contaminates.