Flexible regulation of the membrane performance via the reconstruction of structural and physicochemical features is a promising technical route for the modification of nanofiltration (NF) membranes. Here we present a facile but effective post-treatment method with a ternary mixture of Ethanol-Water-NaOH (EWN). It was demonstrated the polyamide (PA) film in the nascent NF membrane could be effectively reconstructed by the EWN which consisted of 1 mol/L NaOH, 70% (v/v) ethanol, and 30% (v/v) ultrapure water. The EWN post-treatment greatly improved the water permeability (almost 100%) while maintaining high Na₂SO₄ rejection (~95.9%), which made membrane separation performance closer to the “upper bound” related to the “trade-off” between water permeability and Na₂SO₄ rejection. This improvement was attributed to the “etching effect” brought by the synergistic interaction between NaOH and ethanol, which partially broke the polyamide chains, thus reducing the PA film thickness from 43.1 nm to 18.5 nm, decreasing the water contact angle from 38° to 28°, and decreasing the zeta potential from −34.4 mV to −69.1 mV. In addition, the long-term stability testing up to 60 h verified the good durability of the post-treated PA film. The performance improvement of different commercial NF membranes confirmed the general applicability of EWN post-treatment.

通过重构结构和物理化学特征来灵活调节膜性能是纳米过滤 (NF) 膜改性的一条有前途的技术途径。在这里，我们提出了一种简单但有效的后处理方法，使用乙醇-水-NaOH (EWN) 的三元混合物。结果表明，由 1 mol/L NaOH、70% ( v /v) 乙醇和 30% (v/v) 超纯水组成的 EWN 可以有效地重建新生 NF 膜中的聚酰胺 (PA) 膜。EWN 后处理大大提高了透水性（几乎 100%），同时保持高 Na ₂ SO ₄截留率 (~95.9%)，这使得膜分离性能更接近与水渗透率和 Na ₂ SO ₄截留率之间的“权衡”相关的“上限” 。这种改进归因于NaOH和乙醇之间的协同作用带来的“蚀刻效应”，部分破坏了聚酰胺链，从而将PA薄膜厚度从43.1 nm降低到18.5 nm，将水接触角从38°降低到28° °，并将 zeta 电位从 -34.4 mV 降低到 -69.1 mV。此外，长达 60 小时的长期稳定性测试验证了后处理 PA 薄膜的良好耐久性。不同商用 NF 膜的性能改进证实了 EWN 后处理的普遍适用性。