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Abstract: Functionalized multiwalled carbon nanotubes (MWNTs) were incorporated into a chitosan membrane for separation of benzene/cyclohexane mixtures by pervaporation. The pristine MWNTs were treated by mixed acid (H2SO4/HNO3=3/1) and then functionalized with isonicotinic acid. Ag+ was grafted to the pyridine ring on the MWNTs by a complexation reaction. Membranes made of chitosan and Ag+/carbon nanotubes were prepared with polysulfone membranes as support. The surface structure of modified MWNTs was examined by FT-IR, TEM, EDS and XPS to assess its morphology. The swelling and pervaporation characteristics of the membranes for separation of benzene/cyclohexane mixtures were investigated. The swelling degree of the membranes in benzene was more than 2.5 times that of the pristine chitosan membrane. The swelling degree was found to increase with the content of the MWNTs–Ag+ in the membrane and the benzene content in the feed. Pervaporation results also showed that the MWNTs–Ag+/chitosan hybrid membrane separation performance is better than MWNTs/chitosan hybrid membrane and pristine chitosan membrane. The permeation flux of the membrane increased, the selectivity increased firstly and then decreased with the increase in the content of MWNTs–Ag+. The selectivity reached 7.89 and the permeate flux was 357.96g/m2 h (the mass ratio of benzene was 50%, the temperature was 20°C) when the percentage by weight of the MWNTs–Ag+ to chitosan was 1.5%. The Arrhenius activation parameter of 1.5% MWNTs–Ag+/chitosan (CS) hybrid membrane is 4.28kJ/mol while 1.5% MWNTs/CS membrane is 10.6kJ/mol in 50% benzene concentration in feed. [Copyright &y& Elsevier]

Abstract: Ultrafiltration (UF) has become an accepted process for drinking water treatment, but membrane fouling remains a significant problem. Polyethersulfone (PES)/SiO2 composite membranes were prepared by phase inversion method with nano-SiO2 as additive. Water contact angle measurement was conducted to investigate the hydrophilicity and surface wettability of the membranes. The effect of SiO2 nanoparticles on the membrane permeation properties, anti-fouling performances, and membrane morphologies and structures was examined and discussed. The influence of SiO2 on the water permeability, anti-fouling of the PES membranes were evaluated by raw water UF experiments. The results showed that the membrane structure was not obviously affected by addition of SiO2, and the membrane performances such as hydrophilicity and anti-fouling ability were enhanced by adding SiO2 nanoparticles. [Copyright &y& Elsevier]

Abstract: A copolymer with a water-soluble polymer was synthesized from acrylic acid (AA) and 2-(dimethylamino) ethyl methacrylate (DMAEMA) by radical polymerization. The composite membrane was prepared with the DMAEMA-AA copolymer as the top layer and a PS ultrafiltration membrane as the support. The permeation of pure CO2 and CH4 through the composite membrane was measured. The effects of feed gas pressure, separation layer thickness, temperature and heat treatment on the composite membrane performance were studied. The results show that the composite membranes possess good CO2 permeance and selectivity of CO2 over CH4. The membrane displays a CO2 permeation rate of 6.12×10−7 cm3(STP) cm−2 s−1 Pa−1 and CO2/CH4 selectivity of 253.1 at 26°C, 1140 Pa of gas pressure. [Copyright &y& Elsevier]

Abstract: A copolymeric membrane material containing an amine group for CO2 facilitated transport was synthesized by radical polymerization of acrylamide and maleic anhydride. The relative molecular weight and chemical structure of the copolymer were analyzed by viscometric measurement, elemental analysis, and FTIR. The copolymeric membranes were prepared. The sorption behavior as well as the permeabilities of the membranes for pure CO2 and CH4 were investigated. The results show that the copolymeric membrane possesses a higher permeability of CO2 and a lower permeability of CH4. The membrane displays a CO2 permeability of 5×10−12 cm3(STP)/cm2.s.pa, and a CH4 permeability of 2×10−13 cm3(STP)/cm2.s.pa. CO2 sorption behavior of the copolymeric membrane, which can be classified as a dual-mode sorption model, and CH4 sorption behavior of the copolymeric membrane accord with the Fickian diffusion model. [Copyright &y& Elsevier]

Two kinds of isocyanate were used to modify graphene oxide (GO) samples. Then, polyimide (PI) hybrid membranes containing GO and modified GO were prepared by in situ polymerization. The permeation of CO 2 and N 2 was studied using these novel membranes. The morphology experiments showed that the isocyanate groups were successfully grafted on the surface of GO by replacement of the oxygen-containing functional groups. After modification, the surface polarity of the GO increased, and more defect structures were introduced into the GO surface. This resulted in a good distribution of more modified GO samples in the PI polymer matrix. Thus, the PI hybrid membranes incorporated by modified GO samples showed a high gas permeability and ideal selectivity of membranes. In addition, enhancement of the selectivity due to the solubility of CO 2 played a major role in the increase in the separation performance of the hybrid membranes for CO 2 , although the diffusion coefficients for CO 2 also increased. Both the higher condensability and the strong affinity between CO 2 molecules and GO in the polymer matrix caused an enhancement of the solubility selectivity higher than the diffusion selectivity after GO surface modification.