Intercalation of zwitterionic surfactants dramatically enhances the performance of low-pressure nanofiltration membrane

Abstract

High-performance nanofiltration membrane with excellent perm-selectivity and fouling resistance was fabricated by layer-by-layer deposition of polyelectrolytes, polyethylenimine (PEI) and polystyrene sulfonate (PSS), with the intercalation of self-assemblies of zwitterionic surfactants, 3-(N, N-Dimethylmyristylammonio) propane sulfonate (SB3-14). The integration of SB3-14 to the polyelectrolyte active layer dramatically enhanced the water permeability of the low-pressure nanofiltration (LNF) membrane without compromising the rejection of humic acid (HA). Specifically, the LNF membrane with intercalation of zwitterionic surfactant self-assemblies achieved a water permeability of up to 131 L m−2 h−1 bar−1 and an HA rejection over 99%. In addition, the intercalation of SB3-14 surfactants also made the LNF membrane significantly smoother and less prone to fouling in long-term LNF operation, leading to higher water flux and HA rejection when the LNF process reached a steady state.