Abstract:

Efficient separation of monovalent/divalent cations is highly demanded in various industrial processes such as water softening, lithium extraction from salt-lake brine, the production of edible salt and the comprehensive treatment of acidic wastewater. Research on the above membrane materials used in these separation systems has advanced significantly in recent years. This paper presented a comprehensive review of the membrane-based technologies for monovalent/divalent cation separation, including selective cation exchange membranes, nanofiltration membranes, supported liquid membranes and ion imprinting membranes. The optimization strategies and underlying mechanisms for the membrane selectivity were highlighted. The characteristics and applicable scenarios of the above membrane processes were compared. Considering this, it was proposed that the selective ion separation was one of the key areas for membrane separation technology. Clarifying the formation and evolution mechanism of the separation layer at the molecular scale was crucial for improving the controllability of interfacial polymerization reactions. Highly selective ion screening can be realized by controllably constructing recognition sites and mass transfer channels for target ions inside the membrane matrix. Novel membrane materials contained intrinsic and regular pore architectures, such MOFs, COFs, two-dimensional layered membranes, etc., had good development potential for fine ion selection.

Key words: cation exchange membranes, nanofiltration membranes, liquid membranes, ion imprinted membranes, monovalent/divalent cation separation

摘要：

各类工业过程如水质软化、食用盐纯化、盐湖卤水提锂、酸和重金属资源回收等对一/二价阳离子高效分离的需求日益增长，近年来，针对上述分离体系的膜材料的研究取得了诸多进展。本文详细总结了针对一/二价阳离子分离的选择性阳离子交换膜、纳滤膜、支撑液膜和离子印迹膜的研究进展，重点梳理了相关膜材料的离子选择性优化思路和机理，对比分析了上述膜过程的特点和适用场景。基于此，作者认为，离子筛分精细化是膜分离技术的重要发展方向。在分子尺度明晰分离层的形成和演化机理，对于提高界面聚合反应可控度，实现在亚纳米尺度膜结构的精细调控至关重要。通过在膜基体内可控构建目标离子的特异性识别位点和传质通道，有望实现高选择性离子筛分。此外，具有本征规则孔道结构的新型分离膜材料，如MOFs、COFs、二维层状结构膜等，在精细筛分方面具有良好的发展潜力。

关键词: 阳离子交换膜, 纳滤膜, 液膜, 离子印迹膜, 一/二价阳离子分离