N-methylglucamine modified poly (vinyl chloride) support assists the construction of uniform dually charged nanofiltration membrane via interfacial polymerization

Support membrane plays a crucial role in interfacial polymerization (IP) reaction for nanofiltration membranes (NFMs) preparation and dramatically affects the properties of NFMs. This paper reported NFMs with improved uniformity and dually charged separation layer, formed on properly modified poly(vinyl chloride) (PVC) substrate by N-methylglucamine (NMG) molecules. The effect of NMG grafting on the structure and performance of PVC UF membranes and NFMs was studied. The results showed that the appropriate grafting of NMG molecules on the surface of PVC UF membrane significantly improved the hydrophilicity of PVC UF membrane without affecting the pore size. It assisted the convenient formation of uniform and defect-free dually charged polyamide separation layer by regulating the adsorption, storage and dispersion of diamine monomers. Simultaneous high rejection for both divalent anions and cations was obtained. This work provides a convenient and effective strategy to construct uniform dually charged NFMs.