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Abstract: A hollow fiber composite membrane was prepared by coating a poly(N,N-dimethylaminoethyl methacrylate)–poly(ethylene glycol methyl ether methyl acrylate) (PDMAEMA–PEGMEMA) skin layer onto a porous polysulfone (PSf) substrate. The influence of fabrication parameters including coating solution concentration and coating times on the permselectivity of the prepared membrane was investigated. For the composite membrane prepared from the optimal fabrication parameter, its CO2 permeance was about 30GPU with CO2/N2 selectivity of 31 at 35°C and 202.65kPa. Moreover, the effects of experimental temperature and pressure on the permselectivity of hollow fiber composite membranes were evaluated. The gas permeance increased with the increase of temperature, which obeyed Arrhenius relation. With the increase of pressure, N2 showed the similar permeance that meant the transport of N2 through membrane followed solution–diffusion mechanism, while for CO2, its permeance underwent a two step change (first increased then decreased) which suggested there might be two transporting models for CO2 (solution–diffusion and facilitated transport). In addition, it was found that water vapor in the feed gas not only caused plasticization, but also enhanced the interaction of CO2 with amino groups in PDMAEMA–PEGMEMA skin layer. Both of the two effects contributed to a higher CO2 permeance compared with the condition that water vapor was absent. [Copyright &y& Elsevier]

Abstract: Matrimid/polysulfone (PSf) dual-layer hollow fiber membranes were fabricated by using co-extrusion and dry-jet wet-spinning phase-inversion techniques. The effects of the spinning dope composition, spinneret dimension, spinneret temperature and the air gap distance on the hollow fiber membranes separation performance were studied. Aging phenomenon was also studied. After coated by 3wt% silicon solution, the hollow fiber membranes have an O2/N2 selectivity of 7.55 at 25°C, 506.625kPa which exceeds the intrinsic value of Matrimid. The membranes have an O2 permeance of 9.36GPU with an apparent dense-layer thickness of 1421Å calculated from the O2 permeability. SEM images show the high porosity underneath the dense skin. It indicates that non-solvent addition is not necessary in the inner spinning dope to induce the macroviod formation. The binodals of the Matrimid/solvent/H2O and PSf/solvent/H2O indicate that the composition of the spinning dope plays an important role in the structure and the gas separation performance of the dual-layer hollow fiber membranes. The delayed demixing of the inner spinning dope may fabricate low resistance support layers in the dual-layer hollow fiber membranes. [Copyright &y& Elsevier]