Systematic choice of crosslinker and filler for pervaporation membrane: A case study with dehydration of isopropyl alcohol–water mixtures by polyvinyl alcohol membranes

Abstract

Poly vinyl alcohol (PVOH) membrane, was crosslinked with 2, 4 and 6 mass% of four different kinds of crosslinkers i.e. glutaraldehyde (GLU), oxalic acid (OA), dimethylol urea (DMU) and tetra ethyl ortho silicate (TEOS) to produce four different kinds of crosslinked PVOH membranes termed here as PVGLU, PVOA, PVDMU and PVTEOS membrane, respectively. These membranes were first used for pervaporative separation of azeotropic feed concentration of 87.7 mass% of isopropyl alcohol (IPA) in water. Among all of these membranes PVOH membrane crosslinked with 2 mass% (of PVOH) GLU i.e. PVGLU2 was found to show optimum flux and water selectivity (79.75 g/m 2 h and 45.23, respectively, at 40 °C) for separation of this IPA–water azeotropic mixture. This PVGLU2 membrane was further filled with 2, 4, and 6 mass% hydrophilic aluminosilicate filler to produce three different filled membranes i.e. F2PVGLU2, F4PVGLU2 and F6PVGLU2, respectively. These three filled membranes were used for separation of the same azeotropic IPA–water mixtures and F6PVGLU2 membrane was found to show optimum flux and selectivity (109.84 g/m 2 h and 72.71, respectively, at 40 °C). This F6PVGLU2 membrane crosslinked with 2 mass% glutaraldehyde and filled with 6 mass% aluminosilicate filler showing optimum flux and selectivity for azeotropic IPA–water mixture was used for dehydration of IPA using IPA–water mixtures containing 75.87–99.36 mass% IPA in water. All of the filled and unfilled membranes synthesized were also characterized by various conventional methods.