核化学与放射化学2025，Vol.47Issue(5)：530-539,10.DOI:10.7538/hhx.2025.YX.2025018
LiCl-KCl共晶盐中Lu在Cu电极上的电化学行为与分离机理
Electrochemical Behavior and Separation Mechanism of Lutetium on Cu Electrode in LiCl-KCl Eutectic Salt
摘要
Abstract
Molten salt electrolysis has the advantages of high temperature resistance,radiation resistance and simple process,etc.,which make it to be a popular method for extraction and separation elements in spent fuel reprocessing.With the recovery of uranium and transuranium elements,lanthanides,as the main components of fission products,gradually accumulate in molten salt,which seriously hinder the recovery of actinides.In order to promote the smooth recovery of actinides and realize the purification of molten salt,the lanthanides must be removed from the molten salt.Lu is the lanthanide element with the largest atomic number,and its deposition potential is closer to that of actinides.The electrochemical study of Lu is of great significance for the extraction of lanthanide elements and the separation of lanthanide and actinide elements.In this work,cyclic voltammetry and square wave voltammetry were used to analyze the electrode reactions of Lu on W and Cu electrodes in LiCl-KCl eutectic salt at 773 K.It can be found that the reaction of Lu on W electrode is reversible process controlled by diffusion,and the diffusion coefficient of Lu(Ⅲ)in molten salt is calculated to be l.32×10-5-1.03×10-5 cm2/s when its concentration is 2.38×10-5-7.00×10-5 mol/cm3.On Cu cathode,the formation of three Lu-Cu intermetallic compounds,CuLu,Cu2Lu and Cu5Lu,is confirmed by cyclic voltammetry,anode and cathode square wave voltammetry.The thermodynamic data such as equilibrium potential,activity and Gibbs free energy of standard molar formation for Lu-Cu intermetallic compounds were measured by open circuit chronopotentiometry,and the results show that the activity and Gibbs free energy of standard molar formation of Cu5Lu are the smallest among Lu-Cu intermetallic compounds,indicating that Cu5Lu is easier formed on Cu electrode.In addition,the kinetic parameters such as the exchange current density,charge transfer resistance and reaction activation energy of Lu(Ⅲ)/Cu5L u were calculated at different temperatures by polarization curves.With the increase of temperature,the exchange current density gradually increases,while the charge transfer resistance gradually decreases,demonstrating that the higher temperature is conducive to the electrode reaction.The separation of Lu was conducted by potentiostatic electrolysis at-2.2 V for 8 h,and the ICP-OES was used to measure the concentration of Lu(Ⅲ)in molten salt.The results show that the concentration of Lu(Ⅲ)in molten salt decreases gradually with the increase of electrolysis time.The extraction rate can reach 97.6％after electrolysis for 8 h.Besides,the results of XRD and SEM-EDS show that the product is composed of Cu and Cu2Lu phases.Thus,Cu electrode can be used to extract lanthanide Lu efficiently.关键词
LiCl-KCl共晶盐/电极过程动力学和热力学/Lu/Cu电极/电化学分离Key words
LiCl-KCl eutectic salt/kinetics and thermodynamics of electrode process/Lu/Cu electrode/electrochemical separation分类
核科学引用本文复制引用
张欣,韦悦周,李文龙,肖钰滢,王国涛,孙拳章,王季,陈立丰,殷祥标,宁顺艳..LiCl-KCl共晶盐中Lu在Cu电极上的电化学行为与分离机理[J].核化学与放射化学,2025,47(5):530-539,10.基金项目
国家自然科学基金(12305388,12205146,U23B20167,22350710186) （12305388,12205146,U23B20167,22350710186）
湖南省自然科学基金(2023JJ40531) （2023JJ40531）
