Stability and pervaporation characteristics of PVA and its blend with PVAm membranes in a ternary feed mixture containing highly reactive epichlorohydrin

Abstract

In order to find an alternative for classical distillation in the recovery of ECH/IPA from azeotropic ECH/IPA/water (50/30/20 w/w, %) mixtures, a pervaporation process has been applied. Membranes from the crosslinking of poly(vinyl alcohol)/poly(vinyl amine) (PVA/PVAm) were prepared, and then the membrane stability and pervaporation efficiency of the crosslinked PVA/PVAm membranes were studied for highly reactive ECH systems containing a ternary feed mixture. From the Fourier-transform infrared (FT-IR) spectroscopy analysis, it was observed that all of the membranes were chemically stable for 15 days of immersion in a 50 : 30 : 20 ECH/IPA/water (w/w, %) feed mixture at 60 °C. The degree of membrane swelling increased with increasing PVAm content in the membrane composition, water content in the feed composition, and feed temperature, which was attributed to the increase in the number of hydrophilic sites in the membrane. The field-emission scanning electron microscopy (FE-SEM) study revealed that higher PVAm content membranes (PVAm1.0 and PVAm1.5) show polymer phase extraction in ECH/IPA/water (50 : 30 : 20) (w/w, %) at 60 °C in long-term stability tests. The pervaporation dehydration characteristics for all of the membranes with the feed comprising an ECH/IPA/water (50 : 30 : 20 by weight) azeotropic mixture at 30 °C were examined and excellent pervaporation dehydration efficiency was found. Quantitatively, the flux increased from 0.025 to 0.32 kg (m² h)⁻¹ and the separation factor decreased from 1908 to 60 with increasing PVAm content in the blended membrane.