Effect of vapor-induced phase separation on the morphology and separation performance of polysulfone hollow fiber membranes

Abstract

The applicability of a membrane technique to a separation process strongly depends on whether the membrane possessing suitable separation performance can be successfully prepared. Among the methods for preparation of membranes, the most widely used one is the phase inversion method [1]. There are several methods to induce phase separation during membrane forming, such as thermally induced phase separation (TIPS), nonsolvent induced phase separation (NIPS), and vapor-induced phase separation (VIPS) [1]. Although the role of VIPS in the formation of flat-sheet membranes was widely studied [2,3], few articles identified the importance of VIPS in the preparation of hollow fiber membranes. In the present work, we fabricated polysulfone (PSf) hollow fiber membranes via the dry/wet spinning process, changing the ambient humidity to demonstrate the effect of VIPS on membrane morphology. Our focus is on how VIPS affects the formation of macrovoids near the outer surface of hollow fibers and the pervaporation performance of 90w% aqueous isopropanol solution through VIPS fabricated PSf hollow fiber membranes.