Separation of VOCs from N2 using poly(ether block amide) membranes

This work deals with the separation of volatile organic compounds (VOCs) from nitrogen streams for organic vapour emission control by poly(ether block amide) membranes. As representative air pollutant VOCs, n‐pentane, n‐hexane, cyclohexane, n‐heptane, methanol, ethanol, n‐propanol, n‐butanol, acetone, dimethyl carbonate, and methyl tert‐butyl ether were used in this study. The separation of both binary VOC/N₂ and multicomponent VOCs/N₂ gas mixtures was carried out, and the membranes exhibited good separation performance. A VOC concentration of more than 90 mol% was achieved at a feed VOC concentration of 5 mol%. It was found that the permeances of the VOCs were mainly dominated by their solubilities in the membrane, whereas the permeance of N₂ was affected by the presence of the VOCs. The permeance of N₂ in the VOC/N₂ mixtures was shown to be higher than pure N₂ permeance due to membrane swelling induced by the VOCs dissolved in the membrane. Nevertheless, theVOC/N₂ selectivity increased with an increase in the feed VOC concentration. Among the VOCs studied, the membrane showed a higher permeance to alcohol VOCs than paraffin VOCs. The effects of feed VOC concentration, temperature, stage cut, and permeate pressure on the separation performance were investigated.     

Influence of the coagulation‐bath temperature on the phase‐separation process of poly(vinylidene fluoride)‐graft‐poly(N‐isopropylacrylamide) solutions and membrane structures

A poly(vinylidene fluoride)‐graft‐poly(N‐isopropylacrylamide) (PVDF‐g‐PNIPAAm) copolymer was synthesized, and flat‐sheet membranes were prepared via the phase‐inversion method with N,N‐dimethylformamide (DMF) as the solvent and water as the coagulation bath. The effects of the coagulation‐bath temperature on poly(vinylidene fluoride) (PVDF)/DMF/water and PVDF‐g‐PNIPAAm/DMF/water ternary systems were studied with phase diagrams. The results showed that the phase‐separation process could be due to the hydrophilicity/hydrophobicity of poly(N‐isopropylacrylamide) at low temperatures, and the phase‐separation process was attributed to crystallization at high temperatures. The structures and properties of the membranes prepared at different coagulation‐bath temperatures were researched with scanning electron microscopy, porosity measurements, and flux measurements of pure water. The PVDF‐g‐PNIPAAm membranes, prepared at different temperatures, formed fingerlike pores and showed higher water flux and porosity than PVDF membranes. In particular, a membrane prepared at 30°C had the largest fingerlike pores and greatest porosity. The water flux of a membrane prepared in a 25°C coagulation bath showed a sharp increase with the temperature increasing to about 30°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polyamide/polyacrylonitrile thin film composites as forward osmosis membranes

Thin film composites (TFCs) as forward osmosis (FO) membranes for seawater desalination application were prepared. For this purpose, polyacrylonitrile (PAN) as a moderately hydrophilic polymer was used to fabricate support membranes via nonsolvent‐induced phase inversion. A selective thin polyamide (PA) film was then formed on the top of PAN membranes via interfacial polymerization reaction of m‐phenylenediamine and trimesoyl chloride (TMC). The effects of PAN solution concentration, solvent mixture, and coagulation bath temperature on the morphology, water permeability, and FO performance of the membranes and composites were studied. Support membranes based on low PAN concentrations (7 wt %), NMP as solvent and low coagulation bath temperature (0 °C) demonstrated lower thickness, thinner skin layer, more porosity, and higher water permeability. Meanwhile, decreasing the PAN solution concentration lead to higher water permeance and flux and lower reverse salt flux, structural parameter, and tortuosity for the final TFCs. Composites made in N,N‐dimethylformamide presented lower permeance and flux for water and salt and higher salt rejection, structural parameter, and tortuosity. FO assay of the composites showed lower water permeance values in saline medium comparing to pure water. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44130.     

Preparation and characterization of dense cellulose film for membrane application

Regenerated cellulose films were prepared with environmentally friendly process by utilized N‐methylmorpholine‐N‐oxide (NMMO)‐Cellulose system. To prepare a dense cellulose film for membrane application, some parameter process which influence porous forming such as cellulose DP, cellulose concentration, addition NMMO in coagulation bath, coagulation bath temperature, and drying condition were investigated. We resumed that the porosity and pore size of cellulose membrane decrease with lower cellulose DP, higher cellulose concentration, addition of NMMO in coagulation bath, applying room temperature in coagulation bath and drying, and applying vacuum on drying process resulted in membranes with porosity in range of 24–41% and pore size 13.4–20.2 nm. The main factor for controlling porosity and pore size of dense cellulose membrane was coagulation process condition especially addition of NMMO into coagulation bath. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of symmetric and asymmetric pure polysulfone membranes for CO2 and CH4 separation

Preparation of pure polysulfone (PSf) membrane for CO₂/CH₄ separation was aimed in this study. Accordingly, the effects of different variables such as: type and concentration of alcohol as external nonsolvent in the coagulation bath, solvent type in the casting solution and also presence of butanol (BuOH) as internal nonsolvent in polymer solution were examined. CO₂ and CH₄ permeabilities of prepared membranes in different coagulation baths follow this order: ethanol‐50% (EtOH‐50%) > isopropyl alcohol‐50% (IPA‐50%) > ethanol‐100% (EtOH‐100%) > IPA‐100%. According to scanning electron microscopy photographs, membrane asymmetry decreased in higher concentration of alcohols and a high symmetric membrane was prepared using IPA‐100% as external nonsolvent. CO₂/CH₄ selectivity improved in the following order: IPA‐100% > EtOH‐100% > IPA‐50% > EtOH‐50%. Then, a high CO₂/CH₄ selectivity (36.40) was obtained employing pure IPA in coagulation bath. When a mixture of NMP/THF was used instead of NMP as solvent, CO₂/CH₄ selectivity increased from 7.10 to 18.50. Thickness of membranes decreased from 124.70 to 72.11 μm by addition of BuOH concentration from 0 to 10 wt% as internal nonsolvent. Consequently, an enhancement in gas permeability was observed in higher BuOH concentrations. POLYM. ENG. SCI., 54:1686–1694, 2014. © 2013 Society of Plastics Engineers     

Separation of CO2 from CH4 by pure PSF and PSF/PVP blend membranes: Effects of type of nonsolvent,solvent, and PVP concentration

Complete CO₂/CH₄ gas separation was aimed in this study. Accordingly, asymmetric neat polysulfone (PSF) and PSF/polyvinylpyrrolidone (PVP) blend membranes were prepared by wet/wet phase inversion technique. The effects of two different variables such as type of external nonsolvent and type of solvent on morphology and gas separation ability of neat PSF membranes were examined. Moreover, the influence of PVP concentration on structure, thermal properties, and gas separation properties of PSF/PVP blend membrane were tested. The SEM results presented the variation in membrane morphology in different membrane preparation conditions. Atomic forced microscopic images displayed that surface roughness parameters increased significantly in higher PVP loading and then gas separation properties of membrane improved. Thermal gravimetric analysis confirms higher thermal stability of membrane in higher PVP loading. Differential scanning calorimetric results prove miscibility and compatibility of PSF and PVP in the blend membrane. The permeation results indicate that, the CO₂ permeance through prepared PSF membrane reached the maximum (275 ± 1 GPU) using 1‐methyl‐2‐pyrrolidone as a solvent and butanol (BuOH) as an external nonsolvent. While, a higher CO₂/CH₄ selectivity (5.75 ± 0.1) was obtained using N‐N‐dimethyl‐acetamide (DMAc) as a solvent and propanol (PrOH) as an external nonsolvent. The obtained results show that PSF/PVP blend membrane containing 10 wt % of PVP was able to separate CO₂ from CH₄ completely up to three bar as feed pressure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1139‐1147, 2013     

Evaluation and fabrication of pore‐size‐tuned silica membranes with tetraethoxydimethyl disiloxane for gas separation

Organic/inorganic hybrid silica membranes were prepared from 1,1,3,3‐tetraethoxy‐1,3‐dimethyl disiloxane (TEDMDS) by the sol‐gel technique with firing at 300–550°C in N₂. TEDMDS‐derived silica membranes showed high H₂ permeance (0.3–1.1 × 10^?6 mol m^?2 s^?1 Pa^?1) with low H₂/N₂ (～10) and high H₂/SF₆ (～1200) perm‐selectivity, confirming successful tuning of micropore sizes larger than TEOS‐derived silica membranes. TEDMDS‐derived silica membranes prepared at 550°C in N₂ increased gas permeances as well as pore sizes after air exposure at 450°C. TEDMDS had an advantage in tuning pore size by the “template” and “spacer” techniques, due to the pyrolysis of methyl groups in air and Si? O? Si bonding, respectively. For pore size evaluation of microporous membranes, normalized Knudsen‐based permeance, which was proposed based on the gas translation model and verified with permeance of zeolite membranes, reveals that pore sizes of TEDMDS membranes were successfully tuned in the range of 0.6–1.0 nm. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

The influence of membrane formation parameters on structural morphology and performance of PES/PDMS composite membrane for gas separation

In this study, influence of membrane preparation parameters on structural morphology and performance of polyethersulfone/polydimethylsiloxane (PES/PDMS) composite membrane was investigated for gas separation. Asymmetric PES flat sheet membranes were composed by phase inversion method and used as supports. PES composite membranes were fabricated by coating silicone rubber as selective layer on the top surface of support. Effects of different concentrations of PES and PDMS, solvent type, and support thickness on membrane performance were investigated for separation of oxygen from nitrogen. The optimized superior membrane was further modified using polyvinylidenfluoride, methanol and ethanol as additives in PES solutions and/or in water coagulation bath to promote the membrane capability. The results showed that addition of ethanol and methanol in cast solution and coagulation bath can greatly affect the morphology and hence the performance of the prepared membranes. The permeance changes have the contrary trend with solubility parameter difference between solvent and nonsolvent mixture, for instance when this parameter difference was lowest, higher permeance was obtained. Support and coating polymer concentration can control the permeance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Optical resolution of (R,S)‐2‐phenyl‐1‐propanol through enantioselective ethycellulose membranes

Enantioselective membrane was prepared using ethyl cellulose (EC) as membrane material. The flux and permselective properties of membrane using aqueous solution of (R,S)‐2‐phenyl‐1‐propanol as feed solution was studied. The employed membrane process was a pressure driven process. All kinds of important conditions including preparation and operation of membranes were investigated in this experimentation. When the membrane was prepared with 18 wt % EC, 20 wt % N,N‐dimethylformamide in casting solution, 13 min evaporation time and 0°C temperature of water bath for the gelation of the membrane, and the operating pressure and feed solution of (R,S)‐2‐phenyl‐1‐propanol were 0.2 MPa and 1.5 mg/mL, respectively, over 90% of enantiomeric excess (e.e.) and 44.2 (mg/m² h) of flux were obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ceramic Membranes for Water Separation from Organic Solvents

Novel hydrophilic SiO_x modified alumina membranes with high separation factors and flux rates have been prepared for the separation of water from organic solvents. For the preparation of the membranes, SiO_x networks are deposited inside the γ‐Al₂O₃ layer of a commercial ultrafiltration membrane by hydrolysis of tetraethylorthosilicate in autoclaves at 250 °C. The transport resistances of the individual membrane layers for the permeation flux are described by a model. The membranes are stable towards solvents to temperatures of at least 150 °C. Pervaporation studies show that water can be separated from solvents such as acetonitrile, tetrahydrofurane, 2‐propanol, ethyl alcohol, dimethylsulfoxide, N, N‐dimethylformamide, and phenol. The separation performance of the membranes allows their use in technical separation processes, especially for the removal of water.     

Preparation of vinyl amine‐co‐vinyl alcohol/polysulfone composite membranes and their carbon dioxide facilitated transport properties

A vinyl amine–vinyl alcohol copolymer (VAm–VOH) was synthesized through free‐radical polymerization, basic hydrolysis in methanol, acidic hydrolysis in water, and an anion‐exchange process. In the copolymer, the primary amino groups on the VAm segment acted as the carrier for CO₂‐facilitated transport, and the vinyl alcohol segment was used to reduce the crystallinity and increase the gas permeance. VAm–VOH/polysulfone (PS) composite membranes for CO₂ separation were prepared with the VAm–VOH copolymer as a selective layer and PS ultrafiltration membrane as a support. The membrane gas permselectivity was investigated with CO₂, N₂, and CH₄ pure gases and their binary mixtures. The results show that the CO₂ transport obeyed the facilitated transport mechanism, whereas N₂ and CH₄ followed the solution–diffusion mechanism. The increase in the VAm fraction in the copolymer resulted in a carrier content increase, a crystallinity increase, and intermolecular hydrogen‐bond formation. Because of these factors, the CO₂ permeance and CO₂/N₂ selectivity had maxima with the VAm fraction. At an optimum applied pressure of 0.14 MPa and at an optimum VAm fraction of 54.8%, the highest CO₂ permeance of 189.4 GPU [1 GPU = 1 × 10^?6 cm³(STP) cm^?2 s^?1 cmHg^?1] and a CO₂/N₂ selectivity of 58.9 were obtained for the CO₂/N₂ mixture. The heat treatment was used to improve the CO₂/N₂ selectivity. At an applied pressure of 0.8–0.92 MPa, the membrane heat‐treated under 100°C possessed a CO₂ permeance of 82 GPU and a CO₂/N₂ selectivity of 60.4, whereas the non‐heat‐treated membrane exhibited a CO₂ permeance of 111 GPU and a CO₂/N₂ selectivity of 45. After heat treatment, the CO₂/N₂ selectivity increased obviously, whereas the CO₂ permeance decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40043.     

Effects of water vapor on gas permeation and separation properties of MFI zeolite membranes at high temperatures

Understanding the effects of water vapor on gas permeation and separation properties of MFI zeolite membranes, especially at high temperatures, is important to the applications of these zeolite membranes for chemical reactions and separation involving water vapor. The effects of water vapor on H₂ and CO₂ permeation and separation properties of ZSM‐5 (Si/Al ～ 80) zeolite and aluminum‐free silicalite membranes were studied by comparing permeation properties of H₂ and CO₂ with the feed of equimolar H₂/CO₂ binary and H₂/CO₂/H₂O ternary mixtures in 300–550°C. For both membranes, the presence of water vapor lowers H₂ and CO₂ permeance to the same extent, resulting in negligible effect on the H₂/CO₂ separation factor. The suppression effect of water vapor on H₂ and CO₂ permeation is larger for the less hydrophobic ZSM‐5 zeolite membrane than for the hydrophobic silicalite membrane, and, for both membranes, is stronger at lower temperatures and higher water vapor partial pressures. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Preparation of PFSA‐PVA/PSf hollow fiber membrane for IPA/H2O pervaporation process

Using Na⁺ form of perfluorosulfonic acid (PFSA) and poly(vinyl alcohol) (PVA) as coating materials, polysulfone (PSf) hollow fiber ultrafiltration membrane as a substrate membrane, PFSA‐PVA/PSf hollow fiber composite membrane was fabricated by dip‐coating method. The membranes were post‐treated by two methods of heat treatment and by both heat treatment and chemical crosslinking. Maleic anhydride (MAC) aqueous solution was used as chemical crosslinking agent using 0.5 wt % H₂SO₄ as a catalyst. PFSA‐PVA/PSf hollow fiber composite membranes were used for the pervaporation (PV) separation of isopropanol (IPA)/H₂O mixture. Based on the experimental results, PFSA‐PVA/PSf hollow fiber composite membrane is suitable for the PV dehydration of IPA/H₂O solution. With the increment of heat treatment temperature, the separation factor increased and the total permeation flux decreased. The addition of PVA in PFSA‐PVA coating solution was favorable for the improvement of the separation factor of the composite membranes post‐treated by heat treatment. Compared with the membranes by heat treatment, the separation factors of the composite membranes post‐treated by both heat treatment and chemical crosslinking were evidently improved and reached to be about 520 for 95/5 IPA/water. The membranes post‐treated by heat had some cracks which disappeared after chemical crosslinking for a proper time. Effects of feed temperature on PV performance had some differences for the membranes with different composition of coating layer. The composite membranes with the higher mass fraction of PVA in PFSA‐PVA coating solution were more sensitive to temperature. It was concluded that the proper preparation conditions for the composite membranes were as follows: firstly, heated at 160°C for 1 h, then chemical crosslinking at 40°C for 3 h in 4% MAC aqueous solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of PES/CA microporous membranes via reverse thermally induced phase separation process

The blend polyethersulfone (PES)/cellulose acetate (CA) flat‐sheet microporous membranes were prepared by reverse thermally induced phase separation (RTIPS) process. The effects of CA content and coagulation bath temperature on membrane structures and properties were investigated in terms of membrane morphology, water contact angle, permeation performance, and mechanical properties. The cloud point results indicated that the cloud point decreased with the increasing content of CA. When the coagulation bath temperature was lower than the cloud point, the membrane formation process underwent nonsolvent induced phase separation (NIPS) process and dense skin layer and finger‐like structure were formed in membranes. These membranes had lower pure water flux and poor mechanical properties. But when the coagulation bath temperature was higher than the cloud point, the membrane formation process underwent RTIPS process. The porous top surface as well as porous cross‐section of the membranes were formed. Therefore, high pure water flux and good mechanical properties were obtained. The contact angles results indicated that the hydrophilicity of the prepared membranes improved obviously with the addition of CA. When the content of CA was 0.5 wt% and the membrane formation temperature was 323K, the PES/CA microporous membrane which was prepared via the RTIPS process displayed a optimal permeability of the pure water flux of 816 L m^?2 h^?1 and the BSA rejection rate of 49.5%, which showed an increase of 48.9% and 23.6% than that of pure PES membrane, respectively. Moreover, the mechanical strengths of the membranes obtained by RTIPS process were better than those membranes prepared by NIPS process. POLYM. ENG. SCI., 58:180–191, 2018. © 2017 Society of Plastics Engineers     

Preparation and characterizaton of poly(dimethyl amino ethyl methacrylate) modified poly(vinyl alcohol) membrane by UV radiation for the permeation of 5‐fluorouracil

Poly(vinyl alcohol) was modified by UV radiation with dimethyl amino ethyl methacrylate (DMAEMA) monomer to get poly(dimethyl amino ethyl methacrylate) modified poly(vinyl alcohol) (PVADMAEMA) membrane. The PVADMAEMA membranes were characterized by Fourier transform infrared spectroscopy. The tensile strength and elongation of PVADMAEMA membranes were measured by Universal Testing Machine. The results of X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that (1) the crystalline area in PVADMAEMA decreased with increasing the content of poly(dimethyl amino ethyl methacrylate) in the membrane. (2) Only one glass transition temperature (T_g) was found for the various PVADMAEMA membranes. It means that poly(dimethyl amino ethyl methacrylate) and PVA are compatible in PVADMAEMA membrane. (3)The T_g of the membrane is reduced with increasing the content of poly(dimethyl amino ethyl methacrylate) in the membrane. The water content on the PVADMAEMA membranes was determined. It was found that the water content on the PVADMAEMA membrane increased with increasing the content of poly(dimethyl amino ethyl methacrylate). The changes of properties enhanced the permeability of 5‐Fluorouracil (5‐Fu) through the PVADMAEMA membranes. A linear relationship between the permeability and the weight percent of poly(dimethyl amino ethyl methacrylate) in the PVADMAEMA membrane is found. It is expressed as P (cm/s) = (9.6 ± 0.4) × 10^?5 + (8.8 ± 0.6) × 10^?5 W _x , where P is the permeability of 5‐Fu through the membrane and W_x is the weight percent of poly(dimethyl amino ethyl methacrylate) in the PVADMAEMA membrane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and performances of bio-sourced nanostructured carbon membranes elaborated by hydrothermal conversion of beer industry wastes

Hydrothermal carbonization (HTC) process of beer wastes (Almaza Brewery) yields a biochar and homogeneous carbon-based nanoparticles (NPs). The NPs have been used to prepare carbon membrane on commercial alumina support. Water filtration experiments evidenced the quasi-dense behavior of the membrane with no measurable water flux below an applied nitrogen pressure of 6 bar. Gas permeation tests were conducted and gave remarkable results, namely (1) the existence of a limit temperature of utilization of the membrane, which was below 100°C in our experimental conditions, (2) an evolution of the microstructure of the carbon membrane with the operating temperature that yielded to improved performances in gas separation, (3) the temperature-dependent gas permeance should follow a Knudsen diffusion mechanism, and (4) He permeance was increasing with the applied pressure, whereas N₂ and CO₂ permeances remained stable in the same conditions. These results yielded an enhancement of both the He/N₂ and He/CO₂ permselectivities with the applied pressure. These promising results made biomass-sourced HTC-processed carbon membranes encouraging candidates as ultralow-cost and sustainable membranes for gas separation applications.     

Preparation of a poly(vinyl chloride) ultrafiltration membrane through the combination of thermally induced phase separation and non‐solvent‐induced phase separation

To regulate the polymer–diluent interaction and control the viscosity of the casting solution, diphenyl ketone (DPK) and a N,N‐dimethylacetamide/N,N‐dimethylformamide mixture were selected as a combined diluent. Poly(vinyl chloride) (PVC) utlrafiltration membranes, which had sufficient mechanical properties for their practical applications because of their bicontinuous spongy structure, were prepared by a combined process of thermally induced phase separation and non‐solvent‐induced phase separation. The phase‐separation mechanism was analyzed. In an air bath, the cast nascent solution immediately transformed into a transparent gel, and liquid–liquid phase separation was induced by a sudden drop in the temperature before crystallization. An ice–water bath was used to coagulate the membrane. The effects of the DPK and PVC concentrations on the membrane structures and performances were mainly investigated. The results show that an increase in the DPK content made the membrane pores change from fingerlike to spongy. Fully spongy pores formed, and the pores size decreased with increasing PVC concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42953.     

Efficient separation of N2 and he at low temperature using MFI membranes

Ultra‐thin MFI membranes were evaluated for N₂/He separation over the temperature range of 85–260 K for the first time. The membranes were rather nitrogen selective at all the conditions investigated. A highest N₂/He selectivity of 75.7 with a high N₂ flux of 83 kg/m²/h was observed at 124 K. The separation was attributed to adsorption selectivity to N₂, effectively hindering the transport of He in the zeolite pores. The exceedingly high permeance even at low temperatures was ascribed to the ultrathin (<1μm) membrane used. As the pressure ratios increased, a better separation performance was obtained. A mathematical model showed the largest difference of adsorbed loading over the film at ca. 120 K was the main reason for the observed maximum selectivity. Further, the modelling indicated the selectivity would increase 2–3 times by reducing the influence of defects, concentration polarization, and pressure drop over the support. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2833–2842, 2016     

Enhanced antipressure ability through graphene oxide membrane by intercalating g-C3N4 nanosheets for water purification

Graphene oxide (GO) membranes have shown great potential for water purification, but their permeability and antipressure ability are poor, which limits their practical applications. In this study, two-dimensional graphitic carbon nitride (g-C₃N₄) nanosheet-intercalated GO (GOCN) membranes were developed to improve the separation performance of GO membranes, especially under high operating pressure. After incorporation of the g-C₃N₄ nanosheets, the amount of permeable nanochannels (wrinkles or corrugation) in the membrane increased; hence, the water permeance was effectively improved (twice as high as that of GO membranes). Moreover, the antipressure performance of the GOCN membranes was significantly enhanced (even below 0.5 MPa pressure) as the nanochannels in the composite membranes become stable and rigid due to the support of the pressure-resistant g-C₃N₄ nanosheets. The good separation performance demonstrates that the intercalation of g-C₃N₄ is an effective strategy to improve the GO-based membrane properties, which can promote their application in water purification.     

A study of gas transport through interfacially formed poly(N,N-dimethylaminoethyl methacrylate) membranes

Gas transport through interfacially formed poly(N,N-dimethylaminoethyl methacrylate) membranes was investigated. The membrane performance for the separation of binary CO₂/N₂, CO₂/CH₄ and CO₂/H₂ mixtures was studied, and the coupling effects between the permeating species were evaluated by comparing the permeance of individual components in the mixture with their pure gas permeance. For the permeation of these binary gas mixtures, the presence of CO₂ was shown to influence the permeation of the other components (i.e., N₂, H₂ and CH₄), whereas the permeation of CO₂ was not affected by these components. In consideration that water vapor is often encountered in applications involving CO₂ separation, the presence of water vapor on the membrane permselectivity was also studied. When hydrated, the membrane was shown to be more permeable to CO₂, while the membrane selectivity did not change significantly. Unlike membranes based on size-sieving of penetrant molecules, the present membranes exploit the favorable interactions between the hydrophilic quaternary amines in the membrane and CO₂, especially in the presence of water vapor in the feed.