活性Cu电极熔盐电解提取变价稀土Tm  

Molten salts electrolytic extraction of variable rare earth Tm using reactive Cu electrode

作　　者：李梅[1] 王季 韩伟[1] 董永昌 Mei Li;Ji Wang;Wei Han;Yongchang Dong(Key Laboratory of Superlight Materials and Surface Technology,Ministry of Education,College of Material Science and Chemical Engineering,Harbin Engineering University,Harbin 150001,China)

机构地区：[1]哈尔滨工程大学材料科学与化学工程学院教育部超轻材料与表面技术重点实验室,哈尔滨150001

出　　处：《中国科学：化学》2019年第1期175-183,共9页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:11675044;11575047;21790373;11875116;21876034);国家重点基础研究发展规划(编号:91326113;91226201);中央高校基本科研业务费专项资金(编号:HEUCFP201849)资助项目

摘　　要：以LiCl-KCl为熔盐体系,采用不同的电化学方法研究变价Tm(Ⅲ)离子在不同电极(W和Cu)上的电化学还原机制.循环伏安、方波伏安、计时电位和反向计时电位等研究结果表明, Tm(Ⅲ)在W电极上的还原是两步电子转移且受扩散控制的过程,并利用Sand方程计算其扩散系数为6.58×10^(-5)cm^2s^(-1).采用循环伏安法和计时电位法研究了Cu电极上电化学提取稀土Tm的机制,发现Tm(Ⅲ)在Cu电极的还原是分步进行的:Tm(Ⅲ)+e~–→Tm(Ⅱ); Tm(Ⅱ)+2e~–+xCu→Cu_xTm.由于二价Tm(Ⅱ)离子在Cu电极上得电子生成Cu_xTm化合物,使Tm(Ⅱ)的还原电位正移.同时根据每个Cu_xTm化合物的析出电位,在Cu电极上进行恒电位电解提取稀土Tm,并利用X射线衍射仪(XRD)和扫描电子显微镜镜能谱仪(SEM-EDS)对提取物进行了表征,结果表明, 4个Cu-Tm金属间化合物可以被选择性地提取.The electrochemical reduction mechanisms of Tm(III)on different electrodes(W and Cu)were studied in LiCl-KCl molten salts.The results of cyclic voltammetry,square wave voltammetry,chronopotentiometry and reverse chronopotentiometry indicated that the electrochemical reaction of Tm(III)on W electrode proceeds in two steps and diffusion-controlled process.The value of diffusion coefficient calculated using the Sand equation was found to be 6.58x10一5 cm2 s1.The mechanism of electrochemical extraction of Tm on Cu electrode was investigated by cyclic voltammetry and chronopotentiometry,which demonstrated that the reduction of Tm(III)on Cu electrode takes place in two steps:Tm(III)+e-→Tm(II);Tm(II)+2e-+xCu→CuxTm.Since the Tm(II)ions obtains two electrons on Cu substrate and reacts with Cu to form CuxTm compounds,the reduction potential of Tm(II)shifts towards more positive direction.Furthermore,metallic Tm was extracted from molten salts on Cu electrode by potentiostatic electrolysis according to the deposition potential of four CuxTm compounds.The products were characterized by XRD and SEM-EDS,which showed that four Cu-Tm intermetallic compounds could be selectively prepared.

关 键 词：熔盐LiCl-KCl 电化学行为 电解提取 恒电位电解 变价稀土 

分 类 号：TF845[冶金工程—有色金属冶金]