Nanofiltration (NF) offers a scalable and energy-efficient method for lithium extraction from salt lakes. However, the selective separation of lithium from magnesium, particularly in brines with high magnesium concentrations, remains a significant challenge due to the close similarity in their hydrated ionic radii. The limited Li⁺/Mg²⁺selectivity of current NF membranes is primarily attributed to insufficient control over pore size and surface charge. In this study, we report the development of an interlayered thin-film composite (iTFC) membrane incorporating functionalized sulfonated carrageenan to regulate the interfacial polymerization process. This integrated interlayer plays a crucial role in controlling the diffusion and spatial distribution of amine monomers, leading to the formation of dense, nano-striped polyamide networks. These structural improvements including refined pore size and reduced negative charge significantly enhanced Li⁺/Mg²⁺selectivity (133.5) and increased permeance by 2.5 times compared to conventional TFC membranes. Additionally, the nano-striped structure optimized the membrane filtration area while minimizing ion transport resistance, effectively overcoming the traditional trade-off between ion selectivity and permeability. This study highlights the potential of iTFC membranes for achieving both high lithium purity and recovery, offering a promising avenue for large-scale lithium extraction from brines.

中文翻译：

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层间聚酰胺膜的纳米形态发生，用于锂提取中的精确离子筛分


纳滤 （NF） 为从盐湖中提取锂提供了一种可扩展且节能的方法。然而，由于水合离子半径非常相似，锂与镁的选择性分离，特别是在高镁浓度的盐水中，仍然是一个重大挑战。当前 NF 膜的有限 Li⁺/Mg²⁺ 选择性主要归因于对孔径和表面电荷的控制不足。在这项研究中，我们报道了一种层间薄膜复合 （iTFC） 膜的开发，该膜掺入了功能化磺化角叉菜胶以调节界面聚合过程。这种集成的夹层在控制胺单体的扩散和空间分布方面起着至关重要的作用，从而形成致密的纳米条纹聚酰胺网络。与传统的 TFC 膜相比，这些结构改进（包括细化的孔径和减少的负电荷）显著提高了 Li⁺/Mg²⁺选择性 （133.5），并将渗透性提高了 2.5 倍。此外，纳米条纹结构优化了膜过滤面积，同时最大限度地减少了离子传输阻力，有效地克服了离子选择性和渗透性之间的传统权衡。这项研究强调了 iTFC 膜在实现高锂纯度和回收率方面的潜力，为从卤水中大规模提取锂提供了一条有前途的途径。