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Sorption and pervaporation experiments were carried out with PVA/PAA cross-linked membranes for the separation of azeotropic methyl tert-butyl ether and methanol mixtures. The influence of the PVA/PAA ratio and liquid mixture composition were investigated. With increasing PAA content in the membranes, solubilities and fluxes decreased and selectivities increased. Total sorption and fluxes increased with increasing concentration of MeOH. Increasing the concentration of MeOH resulted in decreasing selectivities. Because of polarity, MeOH permeated selectively through the membranes. Sorption results showed the same tendency with pervaporation results.

Tested membranes are MeOH selective. Sorption and pervaporation experiments show that pervaporation characteristics can be controlled with adjusting PVA/PAA ratio in the membranes. Sorption may increase with higher MeOH concentration and this causes higher permeability, but because of the decline of the selective sorption, pervaporation selectivity decreases also. As the cross-linking agent in the membrane increases, cross-linking degree also increases. Therefore, swelling decreases. Because the membrane acts as a perm-selective medium, preferential sorption increases. Since polymer segment mobility decreases with cross-linking, the diffusion of penetrants through the membranes also decreases. Lower diffusion and lower sorption cause lower flux and higher selectivity. Pervaporation has been considered as an alternative separation technique. It may not be practical to separate completely any entire reactor effluents or it may not replace distillation columns in the petrochemical industry. Pervaporation should be used in combination with a conventional separation technique such as a hybrid distillation–pervaporation system to break the azeotropy economically.