Poly(vinyl alcohol)-zeolite T mixed matrix composite membranes for pervaporation separation of water+1,4-dioxane mixtures

Poly(vinyl alcohol) and zeolite T mixed matrix composite membranes prepared by solution casting method followed by crosslinking with glutaraldehyde were tested for pervaporation (PV) separation of water+ 1,4-dioxane mixtures. PV separation characteristics of the crosslinked composite membranes were studied at varying feed water compositions and temperatures. It was found that the composite membrane containing 15 wt.% of zeolite T (PVA-3) gave the higher separation factor of 1689 for 10 wt.% water containing feed mixture as compared to higher water composition of the feed mixtures. Comparatively, a low selectivity of 59 was observed for plain crosslinked PVA membrane at 10 wt.% water in the feed mixture; this value further decreased with increasing water concentration of the feed mixture. Flux for plain PVA membrane increased from 0.128 to 0.247 kg/m(2) h over the studied water composition range of 10-30 wt.% in the feed, while for the same feed water compositions, flux values for PVA-3 membrane were higher, which increased from 0.213 to 0.309 kg/m(2) h. Observed flux was higher for composite membranes, but lower for plain crosslinked PVA membrane; at the same time, selectivity was also higher for PVA composite membranes. Similar trends were observed at 40 and 50 degrees C when PV experiments were performed for 10 wt.% water containing feed mixture. With increasing temperature, flux increased considerably, but selectivity decreased. The PV performance was also studied by calculating permeation flux (J), selectivity (alpha), pervaporation separation index (PSI) and enrichment factor (B). Permeation flux followed the Arrhenius trends over the investigated range of temperature. (c) 2007 Elsevier B.V. All rights reserved.