Synthesis of membranes for the dehydration of water‐acetic acid mixtures by pervaporation, 1. Polymer material selection

Poly(vinyl alcohol) (PVA) was studied for use as a basic material for membrane preparation with the aim of dehydrating water‐acetic acid mixtures. Membranes of different nature were made by blending a PVA sample of 96% hydroxyl content with a polyacid or a polybase counterpolymer in water, followed by complete evaporation. The PVA‐polybase blends gave membranes of low selectivity, unsuitable for dehydration. The membrane M5, made of a 1 : 1 (by wt.) blend of PVA with a special grade of polyhydroxycarboxylic acid (PHC1), presents a good combination of selectivity and permeability. It was studied in a water‐acetic acid mixture containing up to 10 wt.‐% of water. The Arrhenius‐type activation energy for the permeation was found to be 9,0 kcal/mol (38 kJ/mol).