Thin-film composite (TFC) membranes prepared by the interfacial polymerization (IP) of amines and trimesoyl chloride (TMC) have been widely utilized for Li/Mg separation from salt-lake brine. The relatively high lithium rejection hinders the achievement of high lithium extraction efficiency. In this study, a polyphenol-metal-assisted method was designed to regulate the structure of polyethylenimine (PEI)-based polyamide nanofiltration (NF) membranes. Tannic acid (TA) was first deposited onto the substrate, followed by the impregnation of the Cu ions-incorporated aqueous PEI monomer solution to establish ternary interactions among PEI, TA, and Cu ions. Based on the synergistic effect of ternary interactions, the resultant PA-TA-Cu membrane possesses ultrathin thickness (≈11 nm), high positive charge, and relatively loose structure. It exhibited a high MgCl rejection (95.9 %) and a low LiCl rejection (17.1 %), with a pure water permanence of 4.87 L m h bar. Furthermore, the NF membrane exhibits a high Li/Mg separation factor (26.5) and excellent long-term stability. This study provides an efficient strategy for fabricating an excellent NF membrane for lithium extraction from salt-lake brines.

中文翻译：

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用于Li+/Mg2+分离的三元配位调节聚酰胺纳滤膜

通过胺和均苯三甲酰氯（TMC）的界面聚合（IP）制备的薄膜复合（TFC）膜已广泛用于从盐湖卤水中分离锂/镁。相对较高的锂截留率阻碍了高锂提取效率的实现。在这项研究中，设计了一种多酚金属辅助方法来调节聚乙烯亚胺（PEI）基聚酰胺纳滤（NF）膜的结构。首先将单宁酸 (TA) 沉积到基材上，然后浸渍掺有铜离子的 PEI 单体水溶液，以建立 PEI、TA 和铜离子之间的三元相互作用。基于三元相互作用的协同效应，所得PA-TA-Cu膜具有超薄的厚度（约11 nm）、高正电荷和相对疏松的结构。它表现出高 MgCl 截留率 (95.9 %) 和低 LiCl 截留率 (17.1 %)，纯水持久性为 4.87 L m h bar。此外，NF膜具有高Li/Mg分离因子（26.5）和优异的长期稳定性。这项研究为制造用于从盐湖卤水中提取锂的优异纳滤膜提供了一种有效的策略。