Separation of NMP/water mixtures by nanocomposite PEBA membrane: Part I. Membrane synthesis, characterization and pervaporation performance Original Research Article

Novel composite poly(ether-block-amide) (PEBA-2533) membranes were prepared in 90:10 v/v ethanol–water mixed solvent system for pervaporation of n-methyl pyrrolidone (NMP)/water mixtures. Hydrophilic 4A zeolite was incorporated to the extent of 10–40% of polymer weight to enhance separation properties. The synthesized membranes were crosslinked with 2% v/v 2, 4-toluylene-diisocyanate (TDI) in hexane medium for 4 h to reduce degree of swelling and improve selective nature with respect to water. Sorption studies were carried out in pure water, NMP and binary mixtures of varying compositions to establish membrane–liquid interactions. Membranes were characterized by FTIR, XRD and SEM to study formation of new functional groups and intermolecular interactions, degree of crystallinity and d-spacing, besides morphologies of surface and cross-section of the composite films, respectively. Effect of feed composition on membrane performance was evaluated using the optimum 30% zeolite-loaded membrane. For a feed mixture containing 2.87 wt.% water, a selectivity of 122 at a reasonable flux of 55 g/m2h was observed. PEBA-2533 membrane appears to have considerable potential for dewatering of highly polar aprotic solvents owing to its ability to dehydrate NMP to purity levels of > 99%. The composite nature of the membrane makes it feasible to fabricate modular configurations for scale-up.