Separation of alcohol-water mixture by pervaporation through a novel natural polymer blend membrane-chitosan/silk fibroin blend membrane

A novel natural polymer blend membrane, namely chitosan/silk fibroin blend membrane, was prepared. The selective solubility and the pervaporation prop erties of alcohol-water mixture were studied. The results showed that the m embrane was water selective and the separation factor of ethanol-water mixt ure could be improved compared to pure chitosan membrane, when silk fibroin content in blend membrane was no more than 40 wt %. The blend membrane exh ibited a best performance, (i.e., the water in permeate was large than 99 w t % when silk content was 20 wt % and the crosslinking agent-glutaraldehyde content was 0.5 mol %). The mechanism of improvement on pervaporation prop erties was explained by reducing the free volume and freeing hydrophilic gr oups of chitosan because of the strong intermolecular hydrogen bond forming between chitosan and silk fibroin in blend membrane. In addition, the infl uence of operation temperature and feed concentration as well as the pervap oration properties of isopropanol-water mixture were also studied. (C) 1999 John Wiley & Sons, Inc.