The impact of end-group grafting on the chlorine resistance of semi-aromatic nanofiltration membranes
Semi-aromatic polyamide nanofiltration membranes play a crucial role in drinking water treatment due to their high retention selectivity,large water flux,ease of integration,and scalability.However,their low resistance to active chlorine limits widespread application.This study investigated the effects of grafting with oxalyl chloride and sulfonyl chloride on enhancing membrane chlorine resistance.Grafting with oxalyl chloride decreased retention rates for xylose and Mg2+,albeit with slightly improved chlorine resistance in lab-made NFlab membranes.In addition,commercial NFH membranes exhibited significantly reduced chlorine resistance after oxalyl chloride grafting.Sulfonyl chloride grafting maintained the filtration performance of the original membrane and notably enhanced chlorine resistance in NFlab membranes.DFT calculations on membrane monomers revealed that the nitrogen in the amide bond was a primary reactive site for hypochlorous acid.Grafting led to minor changes in geometric configuration and reaction sites but increased the negative charge on the amide nitrogen.Transition state optimizations demonstrated that sulfonyl chloride grafting increased the reaction barrier for amide bond with hypochlorous acid,thereby improving membrane chlorine resistance.
semi-aromatic nanofiltration membranechlorinationretention rategraftingreaction energy barrier
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维普
