Preparation and characterization of PVA thin-film composite membrane for pervaporation dehydration of ethanol solution

Abstract

These days, ethanol fuel has been widely consumed worldwide to replace gasoline due to its possible environmental and long-term economic advantages. In detail, the ethanol fuel (purity ≥ 99.5 wt%) has been produced by traditional separation processes such as azeotropic distillation or molecular sieve adsorption, which excessively employs energy and capital cost. The pervaporation has already been considered as an effective alternative to conventional methods because of its high separation efficiency and low power consumption. Pervaporation separation of ethanol/water solution using hydrophilic membranes has been extensively studied owing to their superior perm-selectivity. In this present work, the polyvinyl alcohol thin-film composite membrane is prepared by casting a thin crosslinked polyvinyl alcohol (PVA) film on the polyacrylonitrile (PAN) porous substrate. The effect of PVA concentration on the pervaporation performance of the fabricated membrane is studied. The physicochemical properties of the prepared membrane are characterized using FTIR, SEM images, and contact angle measurements. The separation performance in terms of permeation flux and selectivity is simultaneously evaluated through a pervaporation dehydration of ethanol/water mixture of 80/20 wt.% at 60°C. The results show that the increase in PVA concentration leads to the decline in the hydrophilicity and the growth of the thickness and swelling degree of the membrane. Therefore, the selectivity of the membrane is found to improve significantly, while the permeation flux decreased with the PVA concentration ranging from 2.5 to 15 wt.%. Based on the results, the PVA membrane prepared from the 10 wt.% concentration is likely to provide high separation performance.