Pervaporation separation and swelling measurement of acetic acid‐water mixtures using crosslinked PVA membranes

Abstract

The pervaporation separation and the swelling behavior of acetic acid-water mixtures were investigated at 30, 40, and 50°C using the crosslinked poly(vinyl alcohol) (PVA) membranes with varying the poly(acrylic acid) (PAA) contents and the acetic acid concentration in the feed mixture. Typically, for the pervaporation separation of 90 wt % acetic acid in the feed, the PVA/PAA = 75/25 membrane gives the separation factor of 795 and the flux of 5.6 g/m2 h at 30°C, respectively. The swelling degree decreases as the PAA content in the membrane decreases to 20 wt % of PAA due to the increase of the crosslinking portion in the membrane and increases beyond this PAA content. The swelling degrees show fairly high at the operating temperatures and the total range of the liquid mixtures in question. The overall activation energy of permeation was also calculated using an Arrhenius type relationship. From this study, it could be concluded that the diffusion step is dominant over the sorption step. © 1997 John Wiley & Sons, Inc.