Enhancing the permselectivity of thin-film composite poly(vinyl alcohol) (PVA) nanofiltration membrane by incorporating poly(sodium-p-styrene-sulfonate) (PSSNa)

Thin-film composite poly(vinyl alcohol) (PVA) nanofiltration membranes with improved permselectivity were prepared by incorporating poly(sodium-p-styrene-sulfonate) (PSSNa). Membranes were prepared through surface coating and in situ cross-linking procedure with porous polysulfone (PSf) membrane as support, PVA and PSSNa as coating materials , and glutaraldehyde as cross-linking agent. The effects of the incorporation of PSSNa on the membrane property and performance were investigated experimentally through ATR-FTIR spectroscopy, AFM analysis, streaming potential analysis, contact angle measurement and cross-flow permeation test. It was found that the incorporation of PSSNa resulted in increased membrane pore size, surface hydrophilicity and negative charge and thereby improved membrane permeability and solute selectivity . The PVA–PSf composite membrane exhibited a pure water flux of about 21.0   l/m 2   h, NaCl rejection of 69.8% and Na 2 SO 4 rejection of 96.5% when tested with 500   mg/l electrolyte aqueous solution at neutral pH and 5.0   bar, while the desired PSSNa/PVA–PSf composite membrane exhibited a higher pure water flux of 41.7   l/m 2   h, lower NaCl rejection of 55.7% and higher Na 2 SO 4 rejection of 98.3%. Moreover, compared with the PVA–PSf composite membrane, the PSSNa/PVA–PSf composite membrane possessed increased water flux and dye removal to anionic dye aqueous solution and improved fouling resistance to BSA aqueous solution.