PERVAPORATION OF AQUEOUS ALCOHOL MIXTURES THROUGH A MEMBRANE PREPARED BY GRAFTING OF POLAR MONOMER ONTO NYLON-4

A hydrophilic pervaporation membrane was prepared via a homografting polymerization of N,N'-(dimethylamino)ethyl methacrylate (DMAEM) onto nylon 4 backbone, DMAEM-g-N4. The water permselectivity was improved by the ammonium quaterization of the pendant N,N'-dimethylamino group on the DMAEM-g-N4 membrane using dimethyl sulfate, DMAEMQ-g-N4. The separation factor and permeation rate for both chemically modified nylon 4 membranes were higher than those of the unmodified nylon 4 membrane. The effects of feed composition, feed temperature, and molar volume of the alcohols on pervaporation performance were investigated. Optimum pervaporation was obtained by a DMAEMQ-g-N4 membrane with a degree of grafting of 12.7% for a 90 wt % ethanol feed concentration, giving a separation factor of 36 and a permeation rate of 564 g/m(2)h. (C) 1995 John Wiley and Sons, Inc.