PVA/Matrimid composite dual-layer hollow fiber membranes for selective water removal from organic solvents by pervaporation

Abstract

Solvent dehydration and recovery are essential operations across various industries, including pharmaceuticals and electronics, where product quality is strongly influenced by residual water content. Ethanol and isopropanol, two widely used solvents, pose significant challenges for dehydration due to azeotrope formation. Conventional approaches are highly energy-intensive and often require entrainers. As an alternative separation process, this study investigates pervaporation using hydrophilic hollow fiber membranes. The main objective was to develop dual-layer hollow fibers combining the complementary properties of Matrimid and polyvinyl alcohol (PVA), previously evaluated in flat-sheet configuration. A Matrimid-based support with a porous internal structure and a thin dense outer layer was fabricated by spinning, followed by deposition of a dense selective PVA layer via dip-coating. Membranes were characterized by SEM, and solvent uptake of both polymers was evaluated. Pervaporation experiments were performed at 50 and 70 °C using ethanol/water and isopropanol/water mixtures containing 2.5–25 wt.% water, including azeotropic compositions. The Matrimid/PVA hollow fiber membrane exhibited promising performance, achieving permeation fluxes of 126 g m^-2 h^-1 for ethanol/water and 121 g m^-2 h^-1 for isopropanol/water at 50 °C and 15 wt.% water in the feed, with water concentrations in the permeate of 95 wt.% and 98 wt.%, respectively.