Abstract In this work, antifouling thin-film composite (TFC) nanofiltration (NF) membrane having zwitterionic PEI moieties was fabricated through the layer-by-layer interfacial polymerization (LbL-IP) via grafting hyperbranched polyethyleneimine (PEI) onto the polyamide surface, followed by in-situ N-methylation of PEI and then quaternization using 3-bromopropionic acid to form zwitterionic PEI. The successful surface modifications of TFC NF membrane with PEI and zwitterionic PEI were confirmed by XPS and ATR-FTIR results. Benefitting from the strong hydrophilicity and hyperbranched steric structure, the zwitterionic PEI-grafted TFC membrane (NF-ZPEI) exhibited a stronger hydration capacity and a thicker hydration layer than the PEI-grafted TFC membrane (NF-PEI) and the control sample (NF-PA). Meantime, the water permeability of NF-ZPEI membrane was enhanced by 11.6% higher than the control sample. The NF-ZPEI membrane also exhibited the improved ion selectivity of having a decreased rejection towards NaCl and maintaining a high rejection towards divalent ions. Dynamic fouling experiments were performed to demonstrate the impact of surface hydrophilicity and surface charge on the membrane fouling performances. Results illustrate that the zwitterionic PEI grafted on the TFC NF membrane mitigated the electrostatic attraction between the membrane surface and protein foulants, and exhibited the improved antifouling properties of having a low flux decline and a high flux recovery. Our work provides some insights on the zwitterionic surface modification of the TFC NF membrane with both the enhanced water permeability and the antifouling properties towards charged foulants.

中文翻译：

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聚乙烯亚胺表面接枝两性离子改性制备防污薄膜复合纳滤膜

摘要 在这项工作中，通过将超支化聚乙烯亚胺 (PEI) 接枝到聚酰胺表面，通过逐层界面聚合 (LbL-IP) 制备了具有两性离子 PEI 部分的防污薄膜复合 (TFC) 纳滤 (NF) 膜，然后是 PEI 的原位 N-甲基化，然后使用 3-溴丙酸季铵化形成两性离子 PEI。XPS 和 ATR-FTIR 结果证实了 TFC NF 膜与 PEI 和两性离子 PEI 的成功表面改性。受益于强亲水性和超支化空间结构，两性离子 PEI 接枝的 TFC 膜（NF-ZPEI）比 PEI 接枝的 TFC 膜（NF-PEI）和对照样品（NF-ZPEI）表现出更强的水化能力和更厚的水化层。 -PA）。与此同时，NF-ZPEI膜的透水性比对照样品提高了11.6%。NF-ZPEI 膜还表现出改善的离子选择性，即对 NaCl 的截留率降低并保持对二价离子的高截留率。进行动态污染实验以证明表面亲水性和表面电荷对膜污染性能的影响。结果表明，接枝在 TFC NF 膜上的两性离子 PEI 减轻了膜表面与蛋白质污染物之间的静电吸引力，并表现出具有低通量下降和高通量恢复的改善的防污性能。