MODIFICATION OF POLY(VINYL ALCOHOL) USING MALEIC-ACID AND ITS APPLICATION TO THE SEPARATION OF ACETIC-ACID WATER MIXTURES BY THE PERVAPORATION TECHNIQUE

The 'solution technique' modification of poly(vinyl alcohol) (PVA) using maleic acid was carried out with the help of triethanolamine/water catalysts. The resulting PVA membranes were characterized by differential scanning calorimetry, infrared spectroscopy, and tensile studies to investigate the reaction between PVA polymer and maleic acid. It was found that the resulting PVA membranes had two portions, branched and crosslinked, and there were no more branched than cross-linked portions. For the pervaporation separation of the acetic acid-water system, two reaction densities (X(cr) = mole maleic acid per mole monomeric unit of PVA) of 0.05 and 0.1 were studied for the separation of the entire range of mixture compositions at 25-degrees-C. The separation factors of the X(cr) = 0.05 modified PVA membranes were higher than those of the X(cr) = 0.1 modified ones and the highest separation factor of 7.80 was obtained at 70 wt% water in the feed with the X(cr) = 0.05 modified PVA membrane.