Dehydration of ethanol-water mixture by vapor permeation through hollow fiber membranes

Abstract

This research programme aims at development of vapor permeation hollow fiber membranes for use in dehydrating industrial solvents especially those that form azeotropes with water. Various polymeric asymmetric hollow fibre membranes have been fabricated via dry-wet phase inversion methods from polymer dopes formulated using polyetherimide (PEI), polyethersulfone (PESf) and polysulfone (PSf) as polymers. The dimensional parameters of the skin layer were determined from nitrogen gas permeation test and the cross-sectional morphologies were examined based on scanning electron microscopy (SEM). The performance of PEI, PESf and PSf vapor permeation membranes for dehydration of ethanol-water mixtures have been investigated under different operating conditions. Among the three membranes tested, PEI membrane was observed to give the best permselectivity for the ethanol-water system investigated. Under the optimal temperature of 110 0C and permeate pressure of 50 mbar, the observed separation factor of water with respect to ethanol and the permeation flux through the PEI membrane are 76 and 592 g/m2.hr respectively.