Effect of blending ratio on pervaporative separation of 1,4-dioxane/water mixtures through PVA–PEI membranes

Blend membranes were made by mixing aqueous solutions of hydrophilic polymers poly(vinyl alcohol) (PVA) and polyethyleneimine (PEI) in different ratios for investigating the separation of 1,4-dioxane/water azeotropic mixture by pervaporation (PV). Water forms azeotrope at 18 wt% concentration with 1,4-dioxane. The resulting membranes were characterized by FTIR to verify the interaction between the homopolymers, wide-angle X-ray diffraction (WAXD) to observe the effect of blending on crystallinity and thermal gravimetric analysis (TGA) to investigate the thermal stability. Sorption studies were carried out to evaluate the extent of interaction and degree of swelling of the blend membranes in pure liquids as well as binary mixtures. The effect of blend composition ratio on membrane parameters such as flux and selectivity was analyzed. An increase in PVA content in the blend caused a reduction in the flux and an increase in selectivity. Among the blends tested in the study, the 5:1 PVA/PEI blend membrane showed the highest separation factor of 44.01 and exhibited a flux of 0.733 kg/m2 h 10 μm for azeotropic feed composition at ambient temperature (30 °C).