Surface-modified polyvinyl alcohol (PVA) membranes for pervaporation dehydration of epichlorohydrin (ECH), isopropanol (IPA), and water ternary feed mixtures

Abstract Conventional distillation failed to separate a ternary azeotropic mixture of ECH, IPA and water (50/30/20 w/w, %) exist in the epoxy resin manufacturing process. Thus, we prepared a PVA-tetraethyl orthosilicate organic–inorganic hybrid membrane and modified the membrane by layer-by-layer deposition of a PVAm/silicotungstic acid polyelectrolyte for the pervaporation (PV) dehydration of ECH/IPA/water mixtures. In PV experiments at 30 °C, the flux decreased from 0.14 to 0.05 kg m-2 h-1 and separation factor increased from and 2099 to 13320 with TEOS addition in the PVA membrane was observed. And for the layer by layer deposition on PVA-TEOS (4) membranes flux increased and separation factor decreased from 0.14 to 0.28 kg m-2 h-1 and 2099 to 416 with the number of layer of deposition were observed respectively. On varying the feed water content from 20 to 10 wt. %, the pervaporation flux at 30 °C decreased from 0.22 to 0.0066 kg m-2 h-1 and the separation factor increased from 1061 to 9094 was observed. By applying the Arrhenius equation, permeation activation energies of ECH and IPA (97.42 and 111.96 kJ mol-1, respectively) are higher than that of water (40.88 kJ mol-1) were reported for the layer by layer membrane.