The Development of Pervaporation Hollow Fiber Membranes for Isopropanol Dehydration

Abstract

Pervaporation is a promising and unique membrane separation process for azeotropic mixtures or close boiling point mixtures separation. The purpose of this work is to fabricate high-performance pervaporation hollow fiber membranes through phase inversion method, and to investigate the effects of modifications on membrane properties and performance for alcohol dehydration. A BTDA-TDI/MDI (P84) asymmetric hollow fiber membrane was developed for pervaporation dehydration of IPA. Effects of various spinning conditions and post treatments on P84 hollow fiber membranes morphology and performance were investigated. Two different post treatment approaches were found on significant performance enhancement by silicone rubber coating and heat treatment, a superior performance was shown. A development of dual-layer hollow fiber membranes using a triple-orifice dual-layer spinneret via co-extrusion phase inversion process was carried out further, by chosen of BTDA-TDI/MDI (P84) co-polyimide to create outer selective layer. It was shown heat treatment densifies the skin of P84 outer-layer and eliminates the pores on the skin of PES inner-layer, and the p-xylenediamine cross-linking modification applied on BTDA-TDI/MDI (P84)/PES dual-layer hollow fiber shows significantly increases the separation factor/selectivity of dual-layer hollow fibers.