Polyamide nanofiltration (NF) membranes with enhanced desalination and fouling resistance were fabricated via grafting N,N-dimethyl-N-2-propenyl-2-propene-1-ammonium chloride-2-propenamide (polyquaternium-7, PQ7), which consists of dimethyl diallyl ammonium chloride and acrylamide monomers. Compared to the control polyamide NF membrane, the PQ7-grafting membrane exhibited higher hydrophilicity, rougher membrane surface, and stronger positive charge. The surface grafting process had no distinct influence on membrane thickness. After modification, the water flux of the resulting membrane improved from 47.8 to 79.6 L m^–2 h^–1 under 5 bar, showing a significant improvement in permeability. Meanwhile, the rejection to divalent ions was elevated to a superior level due to the introduction of the positively charged quaternary ammonium groups from PQ7. Furthermore, the antifouling evaluation indicated that the modified polyamide NF membrane owed superior flux recovery capacity and fouling resistance to both sodium alginate solution and bovine serum albumin. Owing to the low cost of the surface modifier and facile grafting process, this strategy has wide application potential in fabricating superior NF membranes used for water softening.

中文翻译：

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通过表面接枝 Polyquaternium-7 实现具有增强的脱盐和防污性能的聚酰胺纳滤膜

通过接枝N , N-二甲基-N-2-丙烯基-2-丙烯-1-氯化铵-2-丙烯酰胺（聚季铵​​盐-7，PQ7）制备了具有增强的脱盐和抗污染性的聚酰胺纳滤（NF）膜，其由二甲基二烯丙基氯化铵和丙烯酰胺单体。与对照聚酰胺NF膜相比，PQ7接枝膜表现出更高的亲水性、更粗糙的膜表面和更强的正电荷。表面接枝过程对膜厚度没有明显影响。改性后，所得膜的水通量从 47.8 L m ^–2 h ^–1提高到 79.6 L m低于 5 bar，显示渗透性显着改善。同时，由于 PQ7 中带正电荷的季铵基团的引入，对二价离子的排斥提高到了更高的水平。此外，防污评估表明，改性聚酰胺 NF 膜对海藻酸钠溶液和牛血清白蛋白均具有优异的通量恢复能力和抗污染性。由于表面改性剂的低成本和简便的接枝工艺，该策略在制造用于软化水的优质 NF 膜方面具有广泛的应用潜力。