School of Chemical and Biological Engineering, College of Engineering, Institute of Chemical Processes (ICP), Seoul National University (SNU), Gwanak-gu, Daehak-dong, Seoul 08826, Republic of Korea; Asian Institute for Energy, Environment & Sustainability (AIEES), Seoul National University (SNU), Gwanak-gu, Daehak-dong, Seoul 08826, Republic of Korea.
School of Chemical and Biological Engineering, College of Engineering, Institute of Chemical Processes (ICP), Seoul National University (SNU), Gwanak-gu, Daehak-dong, Seoul 08826, Republic of Korea.
J Colloid Interface Sci. 2017 Nov 15;506:644-648. doi: 10.1016/j.jcis.2017.07.054. Epub 2017 Jul 18.
Electrochemical selective ion separation via capacitive deionization, for example, separation of lithium resource from brine, using lithium ion batteries is proposed and demonstrated to have the potential for separating specific ions selectively from a solution containing diverse ions. This separation method is of great industrial concern because of applicability in various fields such as deionization, water softening, purification, heavy metal removal, and resource recovery. Nevertheless, besides the selectivity of materials for lithium ion batteries toward Li, there is very little investigation on the selectivity of the materials for sodium ion batteries toward Na. Here, the electrochemical selectivity of sodium manganese oxide (NaMnO), one of the most widely used material in sodium ion batteries, for Na and other cations (K, Mg, and Ca) is investigated. Selective Na separation using the system consisting of NaMnO and a Ag/AgCl electrode is successfully demonstrated from a solution containing diverse cations (Na, K, Mg, and Ca) via a two-step process that involves a capturing step (charging process) and a releasing step (discharging process). The results showed that NaMnO has over 13 times higher selectivity for Na than for K and 6-8times higher selectivity for Na than for Mg and Ca in the electrolyte containing equal concentrations of the respective ions. Additionally, as a practical demonstration, Na was successfully separated from an industrial raw material used for pure KOH production (estimated ratio of Na:K=1:200).
通过电容去离子（Capacitive Deionization，CDI）进行电化学选择性离子分离，例如从卤水中分离锂资源，使用锂离子电池被提出并证明具有从含有多种离子的溶液中选择性分离特定离子的潜力。这种分离方法引起了工业界的极大关注，因为它适用于脱盐、水软化、净化、重金属去除和资源回收等各种领域。然而，除了锂离子电池对锂离子的材料选择性之外，对钠离子电池对钠离子的材料选择性的研究很少。在这里，研究了钠离子电池中最广泛使用的材料之一——锰酸钠（NaMnO）对 Na 和其他阳离子（K、Mg 和 Ca）的电化学选择性。通过两步过程（捕获步骤（充电过程）和释放步骤（放电过程）），成功地从含有多种阳离子（Na、K、Mg 和 Ca）的溶液中使用 NaMnO 和 Ag/AgCl 电极的系统来实现选择性的 Na 分离。结果表明，在含有各离子等浓度的电解质中，NaMnO 对 Na 的选择性是 K 的 13 倍以上，对 Na 的选择性是 Mg 和 Ca 的 6-8 倍以上。此外，作为实际演示，成功地从用于纯 KOH 生产的工业原料（估计 Na:K 比为 1:200）中分离出了 Na。
