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 demethyl 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/m2h.