Poly(vinyl alcohol)-iron oxide nanocomposite membranes for pervaporation dehydration of isopropanol, 1,4-dioxane and tetrahydrofuran

Poly(vinyl alcohol) (PVA)-based nanocomposite membranes were prepared by coprecipitation of different amounts of Fe(II) and Fe(III) taken in an alkaline medium and their pervaporation (PV) performances were investigated to dehydrate isopropanol, 1,4-dioxane and tetrahydrofuran (THF) from aqueous feeds containing 10–20 wt.% of water in isopropanol and 1,4-dioxane, 5–l5 wt.% of water in THF. The freestanding membranes were characterized by the dynamic mechanical thermal analyzer (DMTA), which showed a shift in glass transition temperature toward higher range along with an increase in storage modulus with increasing amount of iron oxide in the PVA matrix. Furthermore, thin layered membranes were cast on polyester fabric cloths as support layers to improve their PV separation performances for all the three mixtures over that of the pristine crosslinked PVA membrane. In particular, the composite membrane prepared by taking 4.5 wt.% of iron oxide showed an improved selectivity with a slight sacrifice in flux compared to membranes containing lower contents of iron oxide as well as the pristine crosslinked PVA membrane. Flux decreased with increasing content of iron in the PVA matrix, while selectivity increased systematically.