Modified polysulfone membranes. III. Pervaporation separation of benzene-cyclohexane mixtures through carboxylated polysulfone membranes

Membranes prepared from carboxylated polysulfone permeated benzene preferen tially from benzene- cyclohexane mixtures by pervaporation. Hydrophilic pol ysulfones containing carboxyl groups with degrees of substitution DSI rangi ng from 0.46 to 1.90 groups per repeating unit were selected for this study . The membrane having a carboxyl group DS of 0.88 showed the best trade-off between flux and permselectivity. The permselectivity towards benzene was 234 at the weight fraction of benzene in feed of 0.1. From pervaporation an d sorption experiments, it was evident that permselectivity toward benzene was due to solubility selectivity. (C) 1999 John Wiley & Sons, Inc.