Tailoring the structure and properties of the polyamide (PA) layer in a straightforward way is considered promising for fabricating advanced thin film composite (TFC) nanofiltration (NF) membranes. Herein, green and cost-effective tannic acid (TA) was used as an effective additive in the aqueous phase to construct TFC NF membranes via interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC). It was found that the introduction of a small quantity of TA could alter the IP process by attracting more PIP monomers, locally enriching them on the substrate and hindering their diffusion toward the water/organic interface via protonation reaction and hydrogen bonding, resulting in a rough and dense PA structure. Besides, characterizations confirmed that the proper incorporation of TA improved the membrane cross-linking degree, surface hydrophilicity and electronegativity. Consequently, the optimal TFC membrane, obtained at a low TA concentration of 0.004 w/v%, exhibited superior separation performance with permeate fluxes of 67.1 LMH and 55.7 LMH and rejections of 97.0% and 94.4% for Na₂SO₄ and MgSO₄ solutions, respectively. Notably, the optimized TFC membrane outperformed its control counterparts, indicating the efficiency of TA incorporation in constructing a high-performance TFC NF membrane. This work provides a straightforward and economic route to fabricate competitive dense NF membranes for water purification.

中文翻译：

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痕量单宁酸辅助的简便，经济途径，可构建用于脱盐的高性能薄膜复合NF膜

认为以简单的方式调整聚酰胺（PA）层的结构和性能有望用于制造高级薄膜复合材料（TFC）纳滤（NF）膜。在本文中，绿色环保且具成本效益的单宁酸（TA）被用作水相中的有效添加剂，以通过哌嗪（PIP）和均苯三甲酰氯（TMC）的界面聚合（IP）来构建TFC NF膜。结果发现，引入TA少量的可通过吸引更多的PIP单体，局部富集它们在所述衬底上并妨碍它们的扩散朝向水/有机接口改变IP处理通过质子化反应和氢键结合，导致PA结构粗糙而致密。此外，表征证实TA的适当引入改善了膜的交联度，表面亲水性和电负性。因此，在0.004 w / v％的低TA浓度下获得的最佳TFC膜表现出优异的分离性能，渗透通量为67.1 LMH和55.7 LMH，Na ₂ SO ₄和MgSO _4的截留率分别为97.0％和94.4％。解决方案。值得注意的是，优化的TFC膜的性能优于对照膜，表明TA掺入在构建高性能TFC NF膜方面的效率。这项工作提供了一种直接且经济的途径来制造竞争性的致密NF膜以进行水净化。