Pervaporation dehydration of ethyl acetate aqueous solution using the doubly modified polyvinyl alcohol (PVA) composite membrane

摘要

Polyvinyl alcohol-tetraethoxysilane-perfluorosulfonic acid (PVA-TEOS-PFSA) hybrid membrane was prepared by sol-gel method through PVA being modified doubly by PFSA and TEOS. With polyacrylonitrile (PAN) ultrafiltration membrane as a substrate membrane, PVA-TEOS-PFSA/PAN composite membrane was fabricated by dip-coating method for pervaporation (PV) dehydration of ethyl acetate (EAc) aqueous solution. The hybrid membrane was characterized by swelling degree, static contact angle, Fourier transform infrared spectra and scanning electron microscope. Effects of PFSA and TEOS contents in coating solution on PV performance of composite membrane were investigated, respectively. With increasing PFSA content, the permeation flux of composite membrane increased, while the separation factor decreased. Just the opposite, the increase of TEOS content resulted in the decrease in permeation flux and the increase in separation factor. In addition, the PV performances of composite membranes were also investigated at different feed temperatures and water concentrations in feed, respectively. The PVA-TEOS-PFSA/PAN composite membrane, which was prepared from coating with PVA/PFSA mass ratio of 80/20 and TEOS content of 20 wt%, exhibited the permeation flux of 347.9 g m~(-2) h~(-1) and the separation factor of 2218 for PV dehydration of 2 wt% water of EAc solution at 40 °C.