Permeabilities and selectivities of gases such as carbon dioxide （CO2）, sulfur dioxide （SO2）, nitrogen （N2） and methane （CH4） in six imidazolium-based ionic liquids （[emim][BF4], [bmim][BF4], [bmim][PF6], [banim][BF4], [bmim][Tf2N] and [emim][CF3SO3]） supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45℃ and pressure of N2 from 100 to 400 kPa. It is found that SO2 has the highest permeability in the tested supported ionic liquid membranes, being an order of magnitude higher than that of CO2, and about 2 to 3 orders of magnitude larger than those of N2 and CH4. The observed selectivity of SO2 over the two ordinary gas components is also striking. It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes, as well as the nature of ionic liquids play important roles in the gas permeation. A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases. By considering the factors that influence the permeabilities and selectivities of CO2 and SO2, it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.
A high-pressure quartz crystal microbalance(QCM)apparatus was developed to investigate the absorption of carbon dioxide in two glassy polymer films—polystyrene(PS)and polyvinylpyrrolidone(PVP)at 40℃ and pressure up to 9.0 MPa.PVP was shown to have better CO2 absorption and chosen as the representative for supercritical impregnation of two model drugs—o-aminobenzoic acid and ibuprofen at 40℃ and pressure up to 8.0 MPa.It was found that the two impregnants were embedded into the polymer with a partition coefficient as high as 104 order of magnitude.Since the sub-microweighing technique established and utilized in this study was simple,convenient and accurate,it was believed that the technique could have wide and effective applications in supercritical impregnation processes.
