Preparation and performance of poly(vinyl alcohol)/polyethyleneimine blend membranes for the dehydration of 1,4-dioxane by pervaporation: Comparison with glutaraldehyde cross-linked membranes

Dense pervaporation (PV) membranes were prepared by blending hydrophilic polymers, poly(vinyl alcohol) (PVA) and polyethyleneimine (PEI), which was then cross-linked by glutaraldehyde (GA) to assess their suitability for the separation of 1,4-dioxane–water mixtures. The membranes were characterized by FTIR to verify the formation of the ionic interaction, wide-angle X-ray diffraction (WAXD) to observe the effect of blending on crystallinity and thermal gravimetric analysis (TGA) to investigate the thermal stability and tensile testing to asses their mechanical stability. The effects of experimental parameters, such as feed composition, permeate pressure and membrane thickness on normalized flux and selectivity were determined for both the membranes and compared. Uncross-linked PVA/PEI and cross-linked PVA/PEI blend membranes were subjected to sorption studies to evaluate the extent of interaction and degree of swelling in a mixture of the two liquids. The membranes were found to have good potential for breaking the azeotrope of 18 wt.% concentration of water, cross-linked PVA/PEI membrane (90 μm thick) exhibited a lower flux (0.22 kg/(m2 h)) and high selectivity (33.34) compared to PVA/PEI blend membrane. Separation factor was found to improve with decreasing feed water concentration, whereas flux decreased correspondingly. High permeate pressure caused a reduction in both flux and selectivity.