Pervaporation study of butanol/water mixtures by polyvinylalchohol (PVA) and polyimide membranes

Abstract

The separation of alcohol and water mixture has been a challenge and received long-term interest in the chemical industry. The pervaporation technology offers a promising option on solving it. In this work, the separation of butanol/water mixtures by polyvinylalcohol (PVA) and polyimide membranes has been studied. The effects of feed composition and temperature on the separation efficiency of water and four butanol mixtures through PVA membrane were investigated by comparing the flux vs. permeance, separation factor vs. selectivity. The relation between membrane separation performance and operation conditions was elaborated intensively in the first time. The deeper insights into the influence of operational history on the membrane performance were obtained through polyimide asymmetric membranes with two different thermal cycle paths. The results show that the separation performance of membranes is strongly operation path-dependent. Further development on the polyimide membrane in the application of pervaporation under harsh environment by blending polyimide with polybenzimidazole (PBI) was attempted. It was found that the high-temperature performance of blend membranes can significantly be improved which suggests that polyimide polymeric chains was stabilized by blending with PBI combined with the thermal annealing treatment.