Pervaporation dehydration of binary and ternary mixtures of n-butyl acetate, n-butanol and water using PVA-CS blended membranes

The blended membranes of polyvinyl alcohol (PVA) and chitosan (CS) (PVA-CS) were prepared for pervaporation dehydration of a binary system of n-butyl acetate/water and a ternary mixture of n-butyl acetate/n-butanol/water. Membranes were characterized by FTIR, DSC and XRD to investigate the intermolecular interactions, the blending compatibility and the effects of blending on crystallinity. Tensile strengths were measured to determine the influence of blending ratios on the membrane's mechanical properties. The membrane's degree of swelling in water dropped significantly with increasing CS fraction. The results agreed well with the calculation of the solubility parameter. Separation factor and permeation flux increased when the temperature was raised for both the binary and ternary pervaporation systems. An optimal separation factor of 27,000 with a total flux of 402 g·m−2·h−1 was obtained using the blend membrane containing 25 wt% CS at 40 °C for the binary system. For the ternary system, the maximum separation factor and total flux were obtained for blend membranes at 75 wt% and 50 wt% CS content, respectively.