LiCl-KCl熔盐中PrCl_(3)在Mo电极上的电化学行为和热力学性质  

The Electrochemical Behavior and Thermodynamic Properties of PrCl_(3)in the LiCl-KCl Molten Salt on the Mo Cathode

作　　者：王有群[1,2] 陈辉 林如山[3] 宋鹏旺[2] 刘云海 WANG Youqun;CHEN Hui;LIN Rushan;SONG Pengwang;LIU Yunhai(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;School of Nuclear Science and Engineering,East China University of Technology,Nanchang 330013,China;Department of Radiochemistry,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]东华理工大学核科学与工程学院,江西南昌330013 [3]中国原子能科学研究院放射化学研究所,北京102413

出　　处：《东华理工大学学报(自然科学版)》2025年第1期94-100,共7页Journal of East China University of Technology(Natural Science)

基　　金：国家自然科学基金联合基金项目“熔盐中分子筛制备及其对铀钚和关键裂片元素固相吸附行为的研究”(U2167223)。

摘　　要：熔盐中锕系元素和裂变产物的热力学和电化学性质决定了熔盐电解干法后处理工艺中两者的分离效率。镨是一种典型的裂变产物,且难以与锕系元素分离。采用方波伏安法、循环伏安法、计时电位法和开路计时电位法等探究了LiCl KCl熔盐中PrCl_(3)在Mo阴极上的电化学行为,得到Pr(Ⅲ)于Mo电极上的扩散系数、Pr(Ⅲ)/Pr表观标准电位、PrCl_(3)热力学函数与温度的关系式。利用X射线衍射仪(XRD)和扫描电子显微镜能谱仪(SEM EDS)表征了LiCl KCl熔盐中恒电流电解PrCl_(3)的产物。结果表明,Pr(Ⅲ)在LiCl KCl熔盐中(于Mo阴极)是一个一步转移3个电子的准可逆反应:Pr(Ⅲ)+3e=Pr。反应是扩散控制的,扩散系数(D)与温度(T)的关系式为ln D=-6.47-4228.85T-1,扩散活化能为35.16 kJ/mol。Pr(Ⅲ)/Pr的表观标准电位与温度的关系式为E_(Pr(Ⅲ)/Pr)^(0*)=-3.672+7.72×10^(-4)T。研究成果将为LiCl KCl熔盐体系中锕系和裂变元素的分离提供基础支撑。The thermodynamic and electrochemical properties of actinides and fission products in molten salt de-termine the separation efficiency of pyrochemical reprocessing by molten salt electrolysis.Praseodymium is an im-portant fission product in spent nuclear fuel,and it is difficult to separate from actinides in the molten salt elec-trolysis pyrochemical reprocessing process.To separate and recover praseodymium from actinides,it is important to study the electrochemical and thermodynamic properties of PrCl_(3)in LiCl-KCl molten salts.Square wave voltam-metry,cyclic voltammetry,chronopotentiometry,and open circuit chronopotentiometry were used to obtain the electrochemical behavior of PrCl_(3)on Mo cathode.The dependence of diffusion coefficient of Pr(Ⅲ),apparent standard potential of Pr(Ⅲ)/Pr and thermodynamic function of PrCl_(3)on temperatures were obtained.The con-stant current electrolysis product of PrCl_(3)in LiCl-KCl molten salt was characterized using an X-ray diffractometer(XRD)and scanning electron microscopy energy-dispersive spectroscopy(SEM-EDS).The results indicate that Pr(Ⅲ)in LiCl-KCl molten salt undergoes a quasi-reversible reaction of transferring three electrons in one step at the Mo cathode:Pr(Ⅲ)+3e=Pr.The relationship between diffusion coefficient(D)and temperature(T)ob-tained by cyclic voltammetry is ln D=-6.47-4228.85T-1,with a diffusion active energy of 35.16 kJ/mol.The relationship between the apparent standard potential of Pr(Ⅲ)/Pr and temperature is obtained as E_(Pr(Ⅲ)/Pr)^(0*)=-3.672+7.72×10^(-4)T.This study will provide fundamental support for the separation of actinide and fission products in the LiCl-KCl molten salt system.

关 键 词：干法后处理 LiCl KCl熔盐 镨 电化学 

分 类 号：TL241.2[核科学技术—核燃料循环与材料]