Han Eui-Gyu, Lee Ji-Hyeon, Kang Moon-Sung
Department of Green Chemical Engineering, College of Engineering, Sangmyung University, Cheonan 31066, Republic of Korea.
Membranes (Basel). 2025 Jan 9;15(1):19. doi: 10.3390/membranes15010019.
Membrane capacitive deionization (MCDI) is an electrochemical ion separation process that combines ion-exchange membranes (IEMs) with porous carbon electrodes to enhance desalination efficiency and address the limitations of conventional capacitive deionization (CDI). In this study, a cation-exchange membrane (CEM) embedded with a metal-organic framework (MOF) was developed to effectively separate monovalent and multivalent cations in influent solutions via MCDI. To fabricate CEMs with high monovalent ion selectivity, ZIF-8 was incorporated into sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) at various weight ratios. The resulting membranes were systematically characterized using diverse electrochemical methods. The ZIF-8-embedded CEMs demonstrated a sieving effect based on differences in ion size and hydration energy, achieving excellent permselectivity for monovalent ions. MCDI tests using the prepared CEMs showed a Na ion removal rate exceeding 99% in Na/Mg and Na/Ca mixed feed solutions, outperforming a commercial membrane (CSE, Astom Corp., Tokyo, Japan), which achieved a removal rate of 94.1%. These findings are expected to provide valuable insights for advancing not only MCDI but also other electro-membrane processes capable of selectively separating specific ions.
膜电容去离子化（MCDI）是一种电化学离子分离过程，它将离子交换膜（IEMs）与多孔碳电极相结合，以提高脱盐效率并解决传统电容去离子化（CDI）的局限性。在本研究中，开发了一种嵌入金属有机框架（MOF）的阳离子交换膜（CEM），以通过MCDI有效分离进水溶液中的单价和多价阳离子。为了制备具有高单价离子选择性的CEM，将ZIF-8以不同的重量比掺入磺化聚（2,6-二甲基-1,4-亚苯基氧化物）（SPPO）中。使用各种电化学方法对所得膜进行了系统表征。嵌入ZIF-8的CEM基于离子大小和水合能的差异表现出筛分效应，对单价离子实现了优异的选择透过性。使用制备的CEM进行的MCDI测试表明，在Na/Mg和Na/Ca混合进料溶液中，Na离子去除率超过99%，优于商业膜（CSE，日本东京阿童木公司），其去除率为94.1%。这些发现有望为推进MCDI以及其他能够选择性分离特定离子的电膜过程提供有价值的见解。
