Properties of modified poly(vinyl alcohol) membranes prepared by the grafting of new polyelectrolyte copolymers for water-ethanol mixture separation

For the preparation of a water-selective membrane for the pervaporation separation of an azeotropic solution, a series of grafted copolymers were synthesized by the reaction of poly(vinyl alcohol) (PVA) with poly(sodium salt styrene sulfonic acid-co-maleic acid) (PSStSA-co-MA). The esterification was performed between the hydroxyl groups of PVA and the carboxylic groups of the copolymer with a heat treatment. PSStSA-co-MA was prepared with sodium salt styrene sulfonic acid and maleic anhydride copolymerization in dimethyl sulfoxide with azobisisobutyronitrile as an initiator. The reaction mechanism and resultant structure were confirmed with IR spectra. The effect of the heat-treatment time on the gel content was investigated. The permeation flux decreased. and the separation factor increased as the crosslinking agent content rose. A membrane containing 15 wt% PSStSA-co-MA was used for water-ethanol azeotropic solution pervaporation at 30degreesC, and a flux of 0.43 kg/m(2) h and a separation factor of 190 were obtained. (C) 2002 Wiley Periodicals, Inc.