Electrochemical deposition of alkaline-earth elements (Sr and Ba) from LiCl-KCl-SrCl2-BaCl2 solution using a liquid bismuth electrode
Electrochemical deposition of alkaline-earth elements (Sr and Ba) from LiCl-KCl-SrCl2-BaCl2 solution using a liquid bismuth electrode
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DOI：
10.1016/j.electacta.2018.05.097
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发表时间：
2018-08
影响因子：
6.6
通讯作者：
T. Lichtenstein;Thomas P. Nigl;N. Smith;Hojong Kim
中科院分区：
文献类型：
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作者：
T. Lichtenstein;Thomas P. Nigl;N. Smith;Hojong Kim
利用碱土金属和液态铋之间的强化学作用，研究了在500 °C的LiClKCl2-BaCl2电解液中，锶和钡在液态铋金属中的电化学沉积，作为一种将稳定的碱土离子从回收使用过的核燃料的熔盐(共晶LiClKCl2)中分离出来的方法。在共晶LiClKCl2中加入5 %的SrCl2和/或BaCl2，在50 mA cm−2的恒流密度下，液态铋电极的阴极放电强度可达2 70 C g-1。铋的使用导致了复杂的电极反应，导致了锶(2.0-6.5 摩尔%)、钡(4.1-12.8 摩尔%)和锂(5.9-16.2 摩尔%)的共沉积，库仑效率达到63-67%。通过结合实验测定的每种碱/碱土金属在铋中的活度，对电极电位的热力学分析也支持了观察到的共沉积。这项工作的结果表明，在熔融盐(Sr2+和Ba2+)中积累的碱土裂变产物可以通过电化学分离回收到液态铋中，这可以作为回收工艺盐(LiClKCl)的关键步骤，以最大限度地减少额外核废料的产生。
Electrochemical deposition of Sr and Ba into liquid Bi metal was investigated in LiCl-KCl-SrCl2-BaCl2electrolytes at 500 °C as a means to separate stable alkaline-earth ions from the molten salts (eutectic LiCl-KCl) utilized for recycling used nuclear fuel, by leveraging the strong chemical interactions between alkaline-earth metals and liquid Bi. The liquid Bi electrodes were subjected to cathodic discharge up to 270 C g–1at a constant current density of 50 mA cm−2in eutectic LiCl-KCl with the addition of 5 mol% total of SrCl2and/or BaCl2. The use of Bi resulted in complex electrode reactions, leading to co-deposition of Sr (2.0–6.5 mol%), Ba (4.1–12.8 mol%), and Li (5.9–16.2 mol%), and coulombic efficiencies of 63–67% were achieved. The observed co-deposition was also supported via thermodynamic analyses of electrode potentials by incorporating the experimentally determined activity values of each alkali/alkaline-earth metal in Bi. The results of this work suggest that alkaline-earth fission products accumulated in molten salts (Sr2+and Ba2+) can be recovered into liquid Bi by electrochemical separation, which could be employed as a critical step for recycling the process salt (LiCl-KCl) in order to minimize the generation of additional nuclear wastes.