Pervaporation of aqueous alcohol mixtures through functionalized syndiotactic poly(styrene-co-4-methylstyrene) membrane

The pervaporation performances of a series of functionalized syndiotactic poly(styrene-co-4-methylstyrene) (SPSM) membranes for various alcohol mixtures were investigated. The effect of functionalization on the thermal properties and polymer structure of the SPSM membranes were also investigated. The crystallinity of the functionalized SPSM membrane is lower than that of the unfunctionalized SPSM membranes. The water molecules preferentially permeate through the SPSM membranes. Compared with unfunctionalized SPSM membranes, the functionalized SPSM membrane effectively increases the membrane formation performances and the pervaporation performances. The optimun pervaporation performance (a separation factor of 510 and permeation rate of 220 g/m2h) was obtained by the bromination of SPSM (SPSMBr) membrane with a 90wt% aqueous ethanol solution.

The functionalization procedure is effective in enhance the pervaporation performances of the SPSM membrane. Especially, the optimun pervaporation performance (a separation factor of 510 and permeation rate of 220 g/m 2h) was obtained by the bromination of SPSM (SPSMBr) membrane with a 90wt% aqueous ethanol solution. The separation factor and permeation rate increase as the feed concentration of ethanol increase for the SPSMBr membranes. At lower feed ethanol concentration, the interaction effect dominates over the plasticizing effect on the SPSMBr membrane so that the permeation rate is smaller than the ideal permeation rate. However, when the feed solution concentration is higher than 50wt%, the plasticizing effect of the permeates (ethanol) becomes dominant and results in permeation enhancement.