Nanofiltration technology holds significant potential for precisely separating monovalent and multivalent ions, such as lithium (Li) and magnesium (Mg) ions, during lithium extraction from salt lakes. This study bridges a crucial gap in understanding the impact of the membrane spatial charge distribution on ion-selective separation. We developed two types of mixed-charge membranes with similar pore sizes but distinct longitudinal and horizontal distributions of oppositely charged domains. The charge-mosaic membrane, synthesized and utilized for ion fractionation for the first time, achieved an exceptional water permeance of 15.4 LMH/bar and a Li/Mg selectivity of 108, outperforming the majority of published reports. Through comprehensive characterization, mathematical modeling, and machine learning methods, we provide evidence that the spatial charge distribution dominantly determines ion selectivity. The charge-mosaic structure excels by substantially promoting ion selectivity through locally enhanced Donnan effects while remaining unaffected by variations in feedwater concentration. Our findings not only demonstrate the applicability of charge-mosaic membranes to precise nanofiltration but also have profound implications for technologies demanding advanced ion selectivity, including those in the sustainable water treatment and energy storage industries.

中文翻译：

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通过异均相电荷分布增强纳滤膜的离子选择性


纳滤技术在从盐湖中提取锂的过程中精确分离一价和多价离子，例如锂 （Li） 和镁 （Mg） 离子，具有巨大潜力。这项研究弥合了理解膜空间电荷分布对离子选择性分离影响的关键差距。我们开发了两种类型的混合电荷膜，它们具有相似的孔径，但带相反电荷的域具有不同的纵向和水平分布。首次合成并用于离子分馏的电荷镶嵌膜实现了 15.4 LMH/bar 的出色透水率和 108 的 Li/Mg 选择性，优于大多数已发表的报告。通过全面的表征、数学建模和机器学习方法，我们提供了空间电荷分布主要决定离子选择性的证据。电荷马赛克结构通过局部增强的 Donnan 效应显着提高离子选择性，同时不受给水浓度变化的影响。我们的研究结果不仅证明了电荷镶嵌膜对精确纳滤的适用性，而且对需要高级离子选择性的技术具有深远的影响，包括可持续水处理和储能行业的技术。