Comprehensive Analysis on Anomalous Phenomenon of Ethanol-Soluble PVB
Membrane for Ethanol Recovery via Pervaporation
Abstract
Poly(vinyl butyral) is selected as a promising ethanol-permselective
membrane based the solubility parameter theory, however it exhibits
anomalous water perm-selectivity in practical pervaporation process.
Comprehensive analysis based on experimental and theoretical methods
were carried out to explore the inherent mechanism of the anomalous
performance. Firstly, sum frequency generation vibrational spectra and
contact angle were developed to quantify the surface reconstruction of
membrane in air and ethanol, which indicated that hydrophilic hydroxyl
tended to expose on membrane surface with ethanol thus improved the
membrane affinity to water. Meanwhile, swelling behaviors proved more
water would accumulate in the ethanol swollen membrane. Furthermore,
theoretical analysis in terms of sorption and diffusion process, based
on the UNIFAC-FV model and Fujita free volume theory, confirmed the
mechanism of anomalous phenomenon of poly(vinyl butyral) membrane. The
comprehensive investigation was expected to provide insights into the
basic separation mechanism of pervaporation process.