摘要
LiCl-KCl熔盐体系中铀与稀土元素在惰性电极上的分离是电解精炼干法流程中去污的关键步骤。采用方波伏安法(SWV)和开路计时电位法(OCP)研究了LiCl-KCl熔盐体系中U^(4+)和Ce^(3+)的电化学行为,探讨了U^(4+)与Ce^(3+)的还原机理,得到了U^(3+)/U和Ce^(3+)/Ce的表观还原电势。随后,采用恒电位电解法电化学分离了UCl_(4)-CeCl_(3)和UCl_(3)-CeCl_(3),使用能量色散X-射线光谱(EDS)和电感耦合等离子体发射光谱(ICP-AES)确定了电解产物中各元素含量及分离因子。电化学行为研究结果表明,U^(4+)分两步还原为金属(U^(4+)→U^(3+)、U^(3+)→U),Ce^(3+)可一步还原为金属。恒电位电解UCl_(4)-CeCl_(3),产物中含有33.0%的Ce,未能有效地分离铀与铈;金属锂还原UCl_(4)得到UCl_(3)后,恒电位电解UCl_(3)-CeCl_(3)得到枝晶状和片状两种形貌的电解产物。ICP-MS分析结果表明,枝晶状电解产物中U和Ce含量分别为93.84%和5.05%,U与Ce的分离因子为155.1;片状电解产物中U和Ce含量分别为92.65%和5.54%,U与Ce的分离因子为131.7。
The separation of uranium from rare earth elements on the inert electrode in the LiCl-KCl molten salt system is a key step in the decontamination of spent fuel for electrorefining pyrochemcal pyroreprocessing.The electrochemical behaviors of U^(4+)and Ce^(3+)in LiCl-KCl molten salt system were investigated by square wave voltammetry(SWV)and open-circuit chronopotentiometry(OCP).The reduction mechanisms of U^(4+)and Ce^(3+)were discussed,and that the apparent reduction potential U^(3+)/U and Ce^(3+)/Ce were obtained.Subsequently,the electrohcemical separation of U from Ce was carried out by potentiostatic electrolysis in the UCl_(4)-CeCl_(3) and UCl_(3)-CeCl_(3) systems.The content and separation factors in the electrolysis product were determined by EDS and ICP-AES.Electrochemical behavioral studies show that U^(4+)is reduced to metal(U^(4+)→U^(3+),U^(3+)→U)in two steps,and that Ce^(3+)can be reduced to metal in one step.The deposition product by potentiostatic electrolysis in the UCl_(4)-CeCl_(3) contains of 33.0%Ce,which indicate it is hard to effectively separate them in this system.After the reduction of UCl_(4) into UCl_(3) using Lithium metal,products with the dendritic and lamellar morphology were obtained by potentiostatic electrolysis of UCl_(3)-CeCl_(3) mixture.The results of ICP-MS indicated that the contents of U and Ce in product with the dendritic morphology were 93.84%and 5.05%respectively with the separation factor of 155.1;the contents of U and Ce in product with the lamellar morphology were 92.65%and 5.54%respectively with the separation factor of 131.7.
作者
王有群
曾德军
林如山
何辉
张志宾
刘云海
叶国安
WANG You-qun;ZENG De-jun;LIN Ru-shan;HE Hui;ZHANG Zhi-bin;LIU Yun-hai;YE Guo-an(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013, China;Department of Radiochemistry, China Institute of Atomic Energy, Beijing 102413, China)
出处
《东华理工大学学报（自然科学版）》
CAS
2021年第1期82-89,共8页
Journal of East China University of Technology(Natural Science)
基金
江西省教育厅资助项目(GJJ160577)
核资源与环境国家重点实验室基金项目(NRE1813)。
关键词
熔盐
干法后处理
铀
铈
电化学分离
molten salt
dry reprocessing
uranium
cerium
electrochemical separation
