A poly(ionic liquid) complex membrane for pervaporation dehydration of acidic water-isopropanol mixtures

Advanced membranes for pervaporation dehydration of acidic mixtures are demanded since the membrane swelling and stability in acidic feed differ from that in neutral feed. Herein we exploited poly(ionic liquid) complex (PILC) membranes featuring high dehydration performance in acidic conditions versus feed temperature and operation time. A poly(ionic liquid), i.e., poly[1-cyanomethyl-3-vinylimidazolium bromide] (PCMVImBr), was synthesized and complexed with sodium carboxymethyl cellulose (CMCNa) to prepare membranes. Chemical structures, compositions, microstructures and surface properties of PCMVIm-CMCNa PILC membranes were characterized by Fourier-transform infrared spectroscopy, element analysis, scanning electron microscopy, atomic force microscopy and water contact angle. The PILC membranes were efficient in dehydrating 10 wt% acidic water-isopropanol mixtures. Water in permeate for PILC membranes was maintained 99.5 ± 0.3 wt% (feed pH: 7–1, feed temperature: 70 °C), in stark contrast to the pristine CMCNa membrane whose separation factor declined significantly from 1791 to 91.