LiCl-KCl中Cs^(+)对La^(3+)电化学行为的影响  

Effect of Cs^(+) on Electrochemical Behavior of La^(3+) in LiCl-KCl

作　　者：罗万 缪继东[1] 杨大伟 刘雅兰[2] 王东东 赵修良[3] LUO Wan;MIAO Ji-dong;YANG Da-wei;LIU Ya-lan;WANG Dong-dong;ZHAO Xiu-liang(Zigong Fourth People's Hospital,Zigong 643099,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;School of Nuclear Science and Technology,University of South China,Hengyang 421000,China)

机构地区：[1]自贡市第四人民医院,四川自贡643099 [2]中国科学院高能物理研究所,北京100049 [3]南华大学核科学技术学院,湖南衡阳421000

出　　处：《核化学与放射化学》2024年第6期563-573,I0003,共12页Journal of Nuclear and Radiochemistry

基　　金：国家自然科学基金资助项目(21790373)。

摘　　要：模拟研究了电解精炼时阳离子裂变产物(Cs^(+))累积在LiCl-KCl中对镧系元素(La)电化学行为的影响。首先,采用循环伏安法测得La^(3+)在W电极上及液态Ga电极上的电化学性质,结果显示在两种电极上其还原电位随着Cs^(+)浓度的增加逐渐负移。随后,采用计时电位法研究了La^(3+)在熔盐中的扩散行为,发现其扩散系数随着Cs^(+)的累积从1.08×10-5cm^(2)/s减小到4.80×10^(-6)cm^(2)/s。最后,利用线性极化法和交流阻抗法研究了La^(3+)在液态Ga阴极上的动力学性质,结果显示随着Cs^(+)浓度增加,交换电流密度(i_(0))从0.302A/cm^(2)减小到0.0845A/cm^(2),反应活化能(E_(a))从26.77kJ/mol增大到39.24kJ/mol。以上结果表明,Cs^(+)在LiCl-KCl中累积时会改变La^(3+)的还原电位、影响还原反应速率。此外,通过拟合交流阻抗谱的等效电路发现,随着Cs^(+)浓度的增加电解质的物理性质也发生改变,电解质的溶液电阻增大。The main objective of developing molten salt electrolysis refining technology is to achieve the effective separation of Ln/An elements.The examination of the electrochemical behavior of lanthanides,with a particular focus on La^(3+) during electrolytic refining,provides valuable insights into the impact of accumulated cationic fission products,notably Cs^(+),on the electrochemical dynamics within a LiCl-KCl molten salt matrix.This investigation employed a comprehensive approach,utilizing advanced simulation techniques alongside experimental methodologies such as cyclic voltammetry,chronoamperometry,linear polarization,and electrochemical impedance spectroscopy,to elucidate the intricate interactions at play in this electrochemical environment.Preliminary evaluations of the electrochemical properties of La^(3+) ions were conducted on both tungsten(W)and liquid gallium(Ga)electrodes using cyclic voltammetry.The results reveal a notable shift in the reduction potential of La^(3+) towards more negative values as the concentration of Cs^(+) increases.This behavior can be ascribed to competitive ion interactions and modifications in the electrochemical milieu,which impede the reduction efficiency of La^(3+) ions.Subsequent experiments employing chronoamperometry were utilized to elucidate the diffusion behavior of La^(3+) ions within the molten salt matrix.The results demonstrate a marked decrease in the diffusion coefficient from 1.08×10^(-5 )cm/s to 4.80×10^(-6)cm^(2)/s as Cs^(+) concentration escalated.This decline suggests a notable impediment to ion mobility,likely due to the increased viscosity and ion crowding within the electrolyte as Cs^(+) accumulates.Further kinetic analyses of the La^(3+) reduction on liquid Ga cathode were conducted utilizing linear polarization and electrochemical impedance spectroscopy.The investigation reveales a substantial decrease in the exchange current density(i_(0))from 0.302 A/cm^(2) to 0.0845 A/cm^(2) with increasing Cs^(+) concentrations,indicating a marked deceleration in th

关 键 词：La^(3+) Cs^(+) LiCl-KCl 液态Ga电极 电化学行为 

分 类 号：TL241.2[核科学技术—核燃料循环与材料] O646[理学—物理化学]