Preparation, characterization, and performance of a novel hollow fiber nanofiltration membrane

Abstract

Nanofiltration (NF) grade hollow fiber membrane was prepared by incorporation of zinc chloride into polysulfone–polyethylene glycol (molecular weight 200) blend. A 1.0 wt% zinc chloride in the blend reduced the molecular weight cut off (MWCO) of hollow fibers from 44 kDa (average pore size 64A⁰) to a nanofiltration range of MWCO 870 Da (average pore size 7.69 A°). MWCO decreased further to 330 Da (average pore size 4.78 A°) on addition of 2.5 wt% zinc chloride. types of NF hollow fiber were spun, corresponding to zinc chloride concentration of 1.0, 1.5, 2.0, and 2.5 wt%. Ternary phase diagram qualitatively explained the denser morphology for various concentrations of zinc chloride. This was supported by scanning electron micrographs of cross-section and top surface of hollow fibers. NF membranes possessed negative surface charge at extreme pH conditions. Rejection of 1000 mg/l sodium chloride solution was in between 38 to 45% at pH 11, and for divalent sodium sulfate, it was in the range of 55 to 62%. Rejection of dye congo red was found to be 100%. NF membranes showed reasonable antifouling characteristics having flux recovery ratio of more than 90% and a flux decline ratio of less than 10%. Copyright © 2015 John Wiley and Sons, Ltd.