Preparation of hollow fiber poly(N,N-dimethylaminoethyl methacrylate)–poly(ethylene glycol methyl ether methyl acrylate)/polysulfone composite membranes for CO2/N2 separation

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 30 GPU with CO2/N2 selectivity of 31 at 35 °C and 202.65 kPa. 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.