Sericin/poly(vinyl alcohol) blend membranes for pervaporation separation of ethanol/water mixtures

Hydrophilic membranes were prepared from sericin and poly(vinyl alcohol) (PVA) for applications in alcohol dehydration by pervaporation. Sericin/PVA blend membranes were prepared by blending sericin and PVA, followed by chemical crosslinking with dimethylolurea. The permeation of water/ethanol mixtures through the membranes was investigated. It was shown that the blend membranes are preferentially permeable to water. In the temperature range of 50–70 °C, a permeate water concentration of 93.1–94.1 wt.% was achieved at 8.5 wt.% water in the feed, which corresponds to a separation factor of ca. 145–172. As a comparison, membranes were also fabricated from pure sericin and PVA alone, and tested for pervaporation separation under the same conditions. In addition, to elucidate the permselectivity of the membrane, sorption/desorption studies were carried out as well to determine the sorption isotherms for both permeating components. It was shown that the membrane permselectivity to water was primarily derived from its sorption selectivity, and there was a strong coupling effect for the permeation and sorption of the permeant in the membranes.