Fabrication of poly(1-vinylimidazole)/mordenite grafting membrane with high pervaporation performance for the dehydration of acetic acid

Abstract

A novel hydrophilic poly(1-vinylimidazole)/mordenite (PVI/MOR) grafting membrane was prepared by free-radical graft polymerization of 1-vinylimidazole (VI) onto the as-synthesized mordenite zeolite membrane. The surface property and the morphology of the membranes were analyzed by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), diffuse reflectance FT-IR spectroscopy (DRIFTS) and thermogravimetric analysis (TGA). The effects of VI concentrations in the grafting medium, separation temperature, feed concentration on selectivity and flux of the obtained membranes for pervaporation dehydration of acetic acid were examined. The PVI/MOR grafting membrane with the VI solution of 15 wt.% astonishingly exhibited the ideal selectivity with water contents in permeates reaching 100.00 wt.% over acetic acid feed concentrations from 71 to 94 wt.% at 80 °C. Both the total fluxes and selectivity for this membrane increased with temperature ranging from 40 to 80 °C. It was suggested that an in situ formed complex between the poly(1-vinylimidazole) (PVI) moiety of the membrane and the acetic acid in the feed played an important role in the separation performance. It not only blocked the permeation of acetic acid through the grain boundary defects but also facilitated the transport of the water molecules, resulting in an ideal selectivity of water over acetic acid.