Effect of membrane morphology in pervaporative separation of isopropyl alcohol–aromatic mixtures— a thermodynamic approach to membrane selection

Isopropyl alcohol (IPA)–benzene and IPA–toluene, which forms azeotropic mixtures, are commonly encountered in pharmaceutical industries. The present study deals with the use of pervaporation to separate these mixtures. For this purpose, several polymeric hydrophilic membranes with variation in solubility parameters such as regenerated cellulose or cellophane, poly(vinyl alcohol) (PVA), cellulose acetate (CA), cellulose diacetate (CDA), and cellulose triacetate (CTA) were studied. Some of these membranes gave a gradual shift of azeotropic point according to the variation of solubility parameter and interaction parameter values between solute and polymer matrix. Regenerated cellulose film gave the best pervaporation performance in terms of IPA selectivity and durability. PVA showed high selectivity with reasonable flux. Poly(dimethylsiloxane), which is hydrophobic, was also studied as an aromatic selective membrane. The experiments were carried out over the entire range of 0–100% at 30°C.