Polyethersulfone Nanocomposite Membranes Research Articles

Enhancing dye removal and antifouling properties of conductive polyethersulfone nanocomposite membranes by analogous zwitterion-functionalized separation layers with tunable surface-charge orientation

Membrane separation has been demonstrated to have enormous potential for alleviating the global scarcity of clean water. However, membrane fouling extremely limits its applications, and on-demand and precise molecular separation is very challenging for traditional membranes. Here, a novel smart voltage-gated membrane with an analogous zwitterion-functionalized separation layer is prepared by combining blending, surface segregation and co-deposition. Intriguingly, amphiphilic sodium styrene-maleic anhydride copolymer (SMANa) anchored on CNTs not only promotes their dispersion in the membrane but also enhances the electroconductivity through the synergistic ionic-electronic conducting effect. More importantly, positively and negatively charged molecular chains mounted on the membrane surface could form different “electric double” layers in response to the voltage stimuli. Consequently, the optimized membrane as the cathode exhibits superior permeations and separations of Congo red (99.9 %, 313.6 L/m2·h·bar) and indigo carmine (96.9 %, 420 L/m2·h·bar), and as the anode displays outstanding permeations and separations of methyl green (98 %, 381.6 L/m2·h·bar), crystal violet (95.7 %, 368.2 L/m2·h·bar) and methyl orange (94.6 %, 166.4 L/m2·h·bar) due to the effective combination of size sieving, electro-enhanced electrostatic repulsion and adsorption-induced electrostatic repulsion effects. Simultaneously, high flux recovery ratios are also achieved due to the superposition of a stable hydration layer and electrochemistry, indicating excellent antifouling properties.

High performance antibiofouling hollow fiber polyethersulfone nanocomposite membranes incorporated with novel surface-modified silver nanoparticles suitable for membrane bioreactor application

Surface-modified silver nanoparticles with amine, thiol, carboxyl, and the thiol-polyvinylpyrroldidone (PVP) functional groups were synthesized as functional filler for nanocomposite membranes for membrane bioreactor (MBR), with the aims to enhance antimicrobial effect of silver, while immobilizing silver nanoparticles inside the matrix of the membrane. Analyses by fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and dynamic light scattering (DLS) proved successful surface modification for each type of nanoparticles, with average particle sizes of 69, 20, 33, and 34 nm for amine, carboxyl, thiol and thiol-PVP modified silver nanoparticles, respectively. Polyethersulfone (PES) based nanocomposite hollow fiber membranes showed different morphology and performance in ultrafiltration and MBR experiments. The surface modifications were able to immobilize silver nanoparticles inside the membrane by providing proper interactions between the nanoparticles and polymer, reducing silver release compared to the unmodified nanoparticles. Modified nanoparticles changed the phase inversion, resulting in different morphology and average pore size in the range of 7.6–28.0 nm. The surface-modified nanoparticles with enhanced antimicrobial activity improved antifouling properties of the nanocomposite membranes, leading to interesting MBR performance improvements, with 122 % increase of flux, 23 % increase of chemical oxygen demand (COD) removal and flux recovery by over 30 %.

Bi4O5I2 nanosheets as a novel nanofiller for fabrication of antifouling polyethersulfone nanocomposite membranes

Bi4O5I2 is one of the bismuth-rich oxyhalides that exhibited impressive activity in the photodegradation of different organic pollutants. In this research, Bi4O5I2 nanosheets were synthesized, characterized, and applied for fabricating a hydrophilic and antifouling polyethersulfone (PES) membrane by blending in the membrane matrix. The prepared nanocomposite membranes exhibited improved antifouling properties especially when UV irradiation was used during the washing of the fouled membranes. Hydrophilicity enhancement and photocatalytic property of the Bi4O5I2 nanosheets have an excellent synergistic effect, which can yield more hydroxyl radicals (•OH) for efficient removal of the foulant from the membrane surface. The pure water flux can achieve 235.4 L/m2 h (3 bar) when 0.5 wt% Bi4O5I2 was used. The addition of the nanosheets to the membrane matrix in low amounts decreased the membrane surface roughness and increased membrane porosity. The BSA, Reactive Orange 16, Reactive Black 5, and Pb(II) filtration tests showed that the 1 wt% Bi4O5I2 PES membranes provided a good performance of 98.3, 70.3, 92.6, and 47.2 % rejection ability, respectively. In this research, for the first time, the Bi4O5I2 photocatalyst was blended into the membrane matrix which provided a new idea for the progress of highly effective self-cleaning ultrafiltration membranes.

Prepare of sunlight response NH2-MIL-125/PES composites ultrafiltration membrane for flux incrementation and fouling alleviation

In this paper, a novel hydrophilic composite polyethersulfone (PES) ultrafiltration membrane was prepared by blending sunlight response photocatalyst NH2-MIL-125 via the phase inversion method. The physical-chemistry performance of membrane was carried out by XRD, FTIR, UV-VIS/DRS, contact angle, and cross-section SEM images. The separation ability, anti-fouling ability, and self-cleaning efficiency of ultrafiltration membrane were analyzed by ultrafiltration experiment using the congo red solution. The results indicate that fouling resistance and the flux recovery ratio of ultrafiltration membrane is significantly improved, and it has higher solar response energy. There was no significant change in the rejection ratio of pollutants before and after illumination. For the pristine PES membrane and the 0.5% NH2-MIL-125/PES nanocomposite membrane, the water flux recovery ratio (FRR) could increase from 37.84% to 77.09%, and the Rr could increase from 22.22% to 44.09%, and the Rir could decrease from 67.11% to 47.09%. In a conclusion, the addition of NH2-MIL-125 at a low concentration could result in membranes with more pure water flux, better rejection, and good fouling resistance compared to the unfilled PES membrane.

The performance of polyethersulfone nanocomposite membrane in the removal of industrial dyes

In the present study, graphene oxide was functionalized by hyperbranched epoxy and then used as an additive in the polyethersulfone membrane. The process of preparation and characterization of the synthesized hyperbranched epoxy, and graphene oxide modification was investigated by some analysis such as XRD, EDAX, FTIR, NMR, and TGA. Morphology of modified nanostructures, their distribution in the membrane matrix, and morphology of membranes were evaluated by TEM, FESEM analysis. Experimental results showed that the microstructure of membranes was affected and improved; the hydrophilicity nature of membranes increased. Pure water flux of prepared nanocomposite membranes was more than neat polyethersulfone one and is at least 69% higher than the non-modified polyethersulfone membrane. The flux recovery ratio, as a measure of antifouling properties, showed that the amount of fouling had been significantly reduced. More importantly, the prepared mixed matrix membranes exhibited excellent performance in the removal of dyes such as methylene blue, methyl orange (MO), bromothymol blue (BTB), crystal violet (CV), acid red 18, and acid yellow 36.

Nanostructured polyethersulfone nanocomposite membranes for dual protein and dye separation: Lower antifouling with lanthanum (III) vanadate nanosheets as a novel nanofiller

A novel polyethersulfone (PES) nanocomposite membrane incorporated with lanthanum vanadate (LaVO3) nanosheets was fabricated based on phase inversion approach. The morphology and the performance of the fabricated nanocomposite membranes were systematically studied by ATR-FTIR, SEM, AFM, porosity, water contact angle, antifouling and rejection measurements. The resulting membranes showed an asymmetric structure with finger-like pores in which the surface roughness declined by adding different dosages of LaVO3 nanosheets. Contact angle measurements proved that the hydrophilicity of the nanocomposite membranes significantly increased. Furthermore, the water flux of the resulting nanocomposite membranes markedly enhanced due to the nanosheets incorporation. Moreover, nanocomposite membranes showed remarkable antifouling properties (flux recovery ratio ~85%) in contrast with the bare PES (flux recovery ratio ~60%). The high retention of Solazol Red SP-3B (~99%) and Bovine serum albumin (BSA) (~99%) as well as the high permeation flux of the fabricated membrane unveiled the multifunctional character of the nanocomposite membrane for purification of dyes and proteins.

Efficient removal of dyes and proteins by nitrogen-doped porous graphene blended polyethersulfone nanocomposite membranes

Nitrogen-doped porous graphene oxide (N-PGO) was synthesized, characterized, and applied as a hydrophilic nanomaterial in fabrication of polyethersulfone (PES) membrane for Reactive Red 195 dye and bovine serum albumin (BSA) protein separation. The N-PGO nanosheets not merely showed a good adhesion towards polymers, but simultaneously promoted hydrogen bonding action. Therefore, high-efficiency permeation passageway in the separation layer of membranes was attained. X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDX) and Fourier transform infra-red spectroscopy (FTIR) analyses approved nitrogen doping, which increased hydrophilicity and hydrogen bonding ability of PGO in water filtration. The pure water permeation of nanocomposite membranes could reach as high as 190 L m−2 h−1 at 3 bar. A dye rejection efficiency higher than 92% and BSA rejection higher than 95% were accordingly obtained. Atomic force microscopy (AFM) images approved formation of a rough surface that was decreased by addition of low amounts of the PGO. SEM images provided from the surface also confirmed enlarged pore size and increased porosity. Antifouling properties were investigated by BSA filtration, and results showed that the flux recovery ratio of the N-PGO membrane was improved. Overall, the N-PGO hybrid membranes exhibited potential for application in separation of typical proteins and dyes with good antifouling properties.

High-flux and antifouling polyethersulfone nanocomposite membranes incorporated with zwitterion-functionalized graphene oxide for ultrafiltration applications

Polyethersulfone (PES) membranes containing cysteine-functionalized graphene oxide (CGO) were prepared to enhance the ultrafiltration performance such as water flux and antifouling property. The synthesis of CGO was achieved through a simple thiol-ene click reaction between graphene oxide and cysteine. Since CGO has a zwitterionic moiety, it was observed to improve the hydrophilicity and negative charge of the membranes. The results of the ultrafiltration test showed that the separation performance of the prepared CGO/PES nanocomposite membranes was much better than that of the pristine PES membrane. For example, the CGO/PES nanocomposite membrane with 0.5wt.% CGO content has the pure water flux and BSA rejection values of 82.6Lm−2h−1 and 99.8%, respectively, while the pristine PES membrane has these values of 51.7Lm−2h−1 and 96.7%, respectively, indicating that the addition of CGO successfully improves the separation performance of PES-based membrane by overcoming the intrinsic trade-off relationship between permeability and selectivity. Furthermore, CGO/PES nanocomposite membranes also showed much better antifouling property than the pristine PES membrane. For example, the flux recovery ratio of the CGO/PES nanocomposite membrane with 0.5wt.% CGO content is 92.1%, while that of the pristine PES membrane is only 47.5%.

Preparation ultrafine l-Methionine (C,N,S triple doped)-TiO2-ZnO nanoparticles and their photocatalytic performance for fouling alleviation in PES nanocomposite membrane

TiO2, and ultrafine l-Methionine (C,N,S triple doped)-TiO2-ZnO nanoparticles (NPs) were synthesized and blended in polyethersulfone (PES) matrix with various loadings (0.1, 0.5, and 1 wt %). The prepared nanoparticles (NPs) were characterized by XRD, FT-IR, FE-SEM, PL, and DRS analyses. The effect of embedded NPs on the morphology and hydrophilic properties of the fabricated membranes was also analyzed by AFM, SEM and contact angle measurement. The results showed that the membrane structure (morphology and porosity) and its hydrophilic properties are changed with addition of the NPs in the PES casting solution. Results showed that the membrane hydrophilicity and permeation flux improved by embedding the NPs in the PES mix matrix. The influence of embedded NPs on the membrane performance and antifouling properties was also studied in a dead end and cross flow systems. The nanofiltration performance was investigated by rejection of Direct Red 16 (DR16). The results indicated that 0.5 wt % of the NPs had the highest pure water flux (PWF), flux recover ratio (FRR), and rejection efficiency compared to the other concentrations of NPs. Finally, the photocatalytic properties of the M3 (optimum blended membrane) and unfilled PES was investigated in a cross flow system for filtration of biologically treated palm oil mill effluent (POME) under continuous visible light irradiation. The value of permeation flux for unfilled PES membrane showed a significant decline while it was not obviously changed for M3 during filtration biologically treated POME under continuous visible light irradiation. The results revealed that the M3 membrane presented the best antibiofouling characteristics due to high hydrophilic properties and low surface roughness and strong photocatalytic activity.

Comparing the effect of incorporation of various nanoparticulate on the performance and antifouling properties of polyethersulfone nanocomposite membranes

We have prepared polyethersulfone (PES) nanocomposite membranes comprising of cloisite 30B clay, SiO2, TiO2, hydroxyl-functionalized multi-walled carbon nanotubes (MWCNTs-OH), and carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH). The nanoparticulate at five different concentrations were added into the polymeric dope solutions including 15 or 18 wt% of PES, N,N-dimethylacetamide (DMAc) or 1-methyl-2-pyrrolidone (NMP) as solvents, and 1 wt% of pore forming agent. These nanoparticulate may improve porosity, hydrophilicity, and open the channels up for improved water transport. Although many nanoparticulate with various properties and functionalities have been used for the same aims, the efforts have been made to choose the best nanomaterial and its loading among these five famous nanofillers for modifying PES ultrafiltration membrane. The nanocomposite membranes showed better antifouling characteristics and water permeability as compared with the pristine PES membrane because of the porosity and hydrophilicity improvements. However, further increasing nanoparticulate loading led to a possible agglomeration and diminished the water flux and fouling resistance. The effect of polymer concentration and solvent showed that membranes fabricated using 15 wt% of PES concentration possessed greater fouling resistance and water flux compared to those of fabricated using 18 wt% of PES concentration. Also, membranes fabricated using DMAc exhibited a more porous structure with considerably greater water flux as compared with those of fabricated using NMP as the solvent. Based on the results, 1 wt% of TiO2 is recommended as the best nanoparticulate for the PES ultrafiltration membrane modification since it exhibited the superlative performance with a 320% water flux enhancement, nearly 98% BSA rejection, and 130% FRR improvement.

The effect of adding sulfonated SiO2 nanoparticles and polymer blending on properties and performance of sulfonated poly ether sulfone membrane: Fabrication and optimization

Sulfonated poly (phthalazinone ether ketone) and modified silica nanoparticles by poly (2-acrylamido-2-methyl-1-propanesulfonic acid) were prepared and their impact investigated on the physicochemical and transport properties of sulfonated poly ether sulfone. To optimize the weight percentage of incorporated components in sulfonated poly ether sulfone nanocomposite membranes and predict their performance, the central composite design (CCD) of the response surface method (RSM) was utilized. The independent parameters (weight percentage of added sulfonated poly (phthalazinone ether ketone) (SPPEK) and nanoparticles) and the responses (water uptake (WU), swelling ratio (SR), δ value, proton conductivity, methanol permeability and selectivity) were developed and verified with experimental data. The optimum parameters for achieving the highest performance represented by proton conductivity of 57.9 mS cm−1, methanol permeability of 3.21 × 10−7 cm2 s−1, and membrane selectivity of 18.03 × 104 s S cm−3 obtained at contents of SPPEK and nanoparticles of 23.07 and 3.9 wt%, respectively. The membrane with optimum additives demonstrated favorable direct methanol fuel cell (DMFC) characteristics such as reduced methanol permeability, high selectivity, and improved mechanical integrity as well as power density.

Effect of detonation nanodiamond on the properties and performance of polyethersulfone nanocomposite membrane

In this study, the nonsolvent induced phase inversion method was applied to prepare polyethersulfone/detonation nanodiamond (PES)/DND nanocomposite membranes for nanofiltration. Nanocomposite membranes containing different amounts of DND (0–1 wt%) were prepared and subjected to structural and separation characterizations. Structural properties of the membranes such as morphology, porosity, mean pore size, water content and water contact angle were investigated. Additionally, separation properties of the membranes were studied using water permeability, bovine serum albumin (BSA) filtration and dye solution rejection as a synthetic wastewater. Results revealed that presence of DND nanoparticles enhanced hydrophilicity and consequently water flux of the nanocomposite membranes compared to the unfilled membrane. The nanocomposite membranes with loading content of 0.5 wt% provide the highest dyes removal (C.I. Reactive Green 19 and C.I. Reactive Orange 29 with two different molecular weights) and also the highest water permeation, i.e., approximately twice of the unfilled membrane. Furthermore, the nanocomposite membranes showed promising antifouling properties during BSA and dyes filtrations.

Synergistic effect of Chitosan-Zinc Oxide Hybrid Nanoparticles on antibiofouling and water disinfection of mixed matrix polyethersulfone nanocomposite membranes

Antifouling polyethersulfone (PES) membranes for water disinfection were fabricated by incorporating varying concentrations of carbohydrate polymer chitosan and Zinc oxide hybrid nanoparticles (CS-ZnO HNPS). The CS-ZnO HNPS were prepared using chemical precipitation method and were characterized using SEM, XRD and FTIR. The membranes were then fabricated by incorporating nanoparticles of CS-ZnO HNPS with three different concentrations of 5%, 10% and 15% w/w in the casting solution of PES through phase inversion method. The influence of nano-sized CS-ZnO HNPS on the properties of PES was characterized to study morphology, contact angle, water retention, surface roughness and permeability flux. The membranes with the maximum concentrations of 15% HNPS resulted in larger mean pore sizes and lowest contact angle value as compare to the pristine PES membrane. The prepared membranes exhibited significant water permeability, hydrophilicity and prevention against microbial fouling. The prepared membranes were observed to have significant antibacterial as well as antifungal properties due to the synergistic effect of chitosan and ZnO against both bacteria of the type of S. Aureus, B. Cereus, E. coli, and fungi such as S. typhi, A. fumigatus and F. solani.

Fabrication and characterization of polyethersulfone nanocomposite membranes for the removal of endocrine disrupting micropollutants from wastewater. Mechanisms and performance

The addition of small amounts of single walled carbon nanotubes (SWCNT) to polyethersulfone (PES) membranes improves the removal and adsorption of endocrine disrupting micropollutants (bisphenol A and nonylphenol). These small amounts of added SWCNT also reduce reversible and irreversible fouling. The isoelectric point of the SWCNT containing membranes decreases when the content of nanotubes increases with more negative charges at alkaline pH.Increasing nanotube loads into PES membranes makes them slightly more hydrophobous empowering the adsorption of bisphenol and nonylphenol, that are also hydrophobous, and making adsorption a key factor in the removal of these micropollutants. Moreover, the increasing voids generated by higher contents of SWCNT increase the adsorption surfaces. An increase in the transmembrane applied pressure decreases the removal and more steeply for the membranes containing more SWCNT most likely because high pressures increase sweeping and disturb adsorption on the inner surfaces.Higher porosities (or equivalently smaller effective membrane thickness), leading to higher water permeabilities, are also obtained for more loaded membranes. Too high SWCNT contents lead to a saturation and decrease of removal probably because high porosities lead to a decrease in adsorption due to both a decrease in the available surface and a clearing out due to convection through the membrane.

Preparation and characterization of polyethersulfone/silver nanocomposite ultrafiltration membrane for antibacterial applications

Antimicrobial ultrafiltration membranes were prepared by coating silver nanoparticles on the surface of polyethersulfone (PES) membranes which were fabricated via phase inversion induced by the immersion precipitation technique, and their morphology and performance were compared with the antimicrobial PES membranes synthesized by adding the silver nanoparticles into the casting solution during the phase inversion process. For this purpose, stable and uniform colloidal solutions of the silver nanoparticles were prepared by chemical reduction of silver salt using fructose and dimethylformamide as a reducing agent. The silver nanoparticles were characterized by ultraviolet–visible spectroscopy, X‐ray powder diffraction and dynamic light scattering analysis. The morphology and surface properties of the prepared membranes were examined by field emission scanning electron microscopy and atomic force microscopy analysis. Moreover, the separation properties, antimicrobial efficiency and amount of silver release from the PES nanocomposite membranes during the cross flow ultrafiltration were determined. The results indicated that the silver content of the coated PES membranes was greater than the membranes fabricated by the solution blending method. Also, the permeation flux of the silver‐coated membranes was similar to the neat PES membranes, while the membranes prepared by the second approach had less flux. The membranes synthesized by both coating and blending methods showed high antimicrobial and bactericidal activity against gram‐negative bacteria such as Escherichia coli and gram‐positive bacteria such as Staphylococcus aureus. Finally, the prepared antimicrobial membranes were successfully used for the ultrafiltration of raw milk to reduce the microbial load during the concentration process. Copyright © 2014 John Wiley & Sons, Ltd.

Synthesis and optimization of PES‐Fe3O4 mixed matrix nanocomposite membrane: Application studies in water purification

A mixed matrix nanocomposite membrane comprising of polyethersulfone (PES) and nano Fe3O4 particles was synthesised with an aim to develop a membrane with superior ability to high water flux while maintaining salt rejection efficiency. The study focused on optimizing the effect of different percentages of nano Fe3O4 particles addition on the membrane pure water flux, and rejection of both the NaCl and MgSO4. The results showed that the PES nanocomposite membrane with 15% Fe3O4 exhibited the highest pure water flux, while the highest rejection of NaCl and MgSO4 belonged to the PES‐10% Fe3O4. The rejection sequence of PES‐10% Fe3O4 membrane was 68% and 82%, respectively. Also it was observed that nano Fe3O4 particles improved membrane hydrophilicity, and helped to construct a membrane with desire surface and cross‐section morphology. POLYM. COMPOS., 34:1870–1877, 2013. © 2013 Society of Plastics Engineers

Desalination of Brackish Water Using Nanofiltration: Performance Comparison of Different Membranes

Characterization and performance screening of NF membranes are essential to evaluate their suitability for application in brackish water desalination. In this study, two commercial and two fabricated nanoparticle-modified polyethersulfone membranes were studied and characterized. In addition, their performance in terms of flux and rejection was investigated. Based on these initial studies, the membranes’ suitability for application in brackish water desalination could be ascertained. This information will also be helpful in further improvement of the membranes and in terms of optimizing their performance. The two commercial NF membranes are NF-1 and ASP30 and the two fabricated membranes are polyethersulfone-nanocomposite membranes (PES-5 % Fe3O4, PES-10 % Fe3O4). Pore size diameter, pore size distribution, and roughness were measured using atomic force microscopy. Surface cleanliness of membranes was investigated by field emission scanning electron microscopy. Hydrophobicity and hydrophilicity were also studied using the contact angle. Flux, permeability, and rejection rates were investigated for all membranes. The NF-1 commercial membrane had the highest rejection rate for divalent salt MgSO4, reaching 92 %, while fabricated membrane PES-5 % Fe3O4 had the highest rejection rate for monovalent NaCl salt, reaching 75 %. Commercial NF-1 and ASP30 membranes showed higher flux than fabricated membranes. ASP30 had the highest flux and permeability (176 and 12.77 l/m−2h−1 bar−1, respectively), while PES-5 % Fe3O4 fabricated membrane had the lowest (47.40 and 4.8 l/m−2 h−1 bar−1, respectively).

Novel polyethersulfone nanocomposite membrane prepared by PANI/Fe3O4 nanoparticles with enhanced performance for Cu(II) removal from water

A novel mixed matrix polymeric membrane was prepared from polyethersulfone (PES) and self-produced polyaniline/iron(II, III) oxide (PANI/Fe3O4) nanoparticles by phase inversion method. The core-shell structured PANI/Fe3O4 nanoparticles were verified and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). Three different amounts of nanoparticles were introduced into the casting solutions to obtain the optimum value. According to the performance test, the membrane with 0.1 wt% nanoparticles indicated the highest Cu(II) ion removal but the lowest pure water flux. This is caused by nanoparticles located in the superficial pores of the membrane during preparation i.e., surface pore blockage. Morphological analysis including field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) as well as membrane performance tests revealed that adsorption is the most possible separation mechanism by the membranes. For better investigation of the adsorption mechanism, several isotherm models such as Langmuir, Freundlich and Redlich-Peterson were tested. Based on the isothermal results, the Redlich-Peterson model offered superior fitness indicating relatively complex adsorption mechanism. The reusability of the nanocomposite membrane was confirmed for several sequential adsorption-desorption processes using EDTA as regenerator.

Enhanced gas permeability by fabricating functionalized multi-walled carbon nanotubes and polyethersulfone nanocomposite membrane

Nanocomposite membranes consisting of 1–10 wt.% multi-walled carbon nanotubes (MWCNTs) embedded in polyethersulfone (PES) have been fabricated via phase inversion method by using N-methyl-2-pyrrolidone as solvent and their transportation properties are evaluated. The functional groups on MWCNTs, crystalline structure and MWCNTs dispersion were characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectra, field emission scanning electron microscopy and transmission electron microscopy. The gas permeation fluxes of the derived nanocomposite membranes are increased by ∼67% without sacrificing selectivity at 5 wt.% MWCNTs introduced. According to diffusivity and solubility results derived from time lag method, the carboxyl groups on MWCNTs have stronger interaction with CO 2, which can increase the solubility of polar gas and limit the solubility of non-polar gas, thus benefiting the CO 2/N 2 gas selectivity.