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

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 & Sons, Ltd.