Abstract Electrodialysis (ED) technique is a typical and promising membrane process, for applications like water treatment and ion separation. Especially, the separation between monovalent and multivalent cations is a current central issue in many industries and academic researches. Herein, a series of novel cation exchange membranes were prepared from quaternized polyaniline modified sulfonated polyphenyl sulfone (SPPSU) by in-situ polymerization-deposited polyaniline followed by quaternizing with methyl iodide. Restricted divalent cation penetration and regulated monovalent cation transport were achieved by elevating the kinetic effect of electrostatic repulsion and narrowing water channel. Importantly, positive charge density of modification layer could be adjusted by controlling the degree of quaternization, which was accompanied by the change of water channel. When evaluated in a simulated mixed salt system (Mg2+/Na+ and Mg2+/Li+), the optimal quaternized polyaniline membrane exhibited a higher perm-selectivity (PNaMg=4.1, PLiMg=1.75) than initial polyaniline modified cation exchange membrane (PNaMg=0.8, PLiMg=0.75), and commercial monovalent-selective cations exchange membrane CIMS (PNaMg=3.56, PLiMg=1.11). This presented strategy is straightforward and effective, demonstrating the effect of surface positive charge layer on perm-selectivity.

中文翻译：

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通过功能层上可调节的电荷密度提高阳离子交换膜的单价选择性

摘要 电渗析（ED）技术是一种典型的、有前景的膜工艺，用于水处理和离子分离等应用。尤其是单价和多价阳离子的分离是当前许多行业和学术研究的核心问题。在此，以季铵化聚苯胺改性磺化聚苯砜（SPPSU）为原料，通过原位聚合沉积聚苯胺，然后用甲基碘进行季铵化，制备了一系列新型阳离子交换膜。通过提高静电排斥的动力学效应和缩小水通道，实现了限制二价阳离子渗透和调节单价阳离子传输。重要的是，可以通过控制季铵化程度来调整改性层的正电荷密度，伴随着水道的变化。在模拟混合盐体系（Mg2+/Na+ 和 Mg2+/Li+）中进行评估时，最佳季铵化聚苯胺膜表现出比初始聚苯胺改性阳离子交换膜（PNaMg=0.8， PLiMg=0.75）和商业单价选择性阳离子交换膜 CIMS（PNaMg=3.56，PLiMg=1.11）。这种提出的策略简单而有效，证明了表面正电荷层对渗透选择性的影响。和商业单价选择性阳离子交换膜 CIMS (PNaMg=3.56, PLiMg=1.11)。这种提出的策略简单而有效，证明了表面正电荷层对渗透选择性的影响。和商业单价选择性阳离子交换膜 CIMS (PNaMg=3.56, PLiMg=1.11)。这种提出的策略简单而有效，证明了表面正电荷层对渗透选择性的影响。