Electrochemical extraction of samarium from molten chlorides in pyrochemical processes
Electrochemical extraction of samarium from molten chlorides in pyrochemical processes
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DOI：
10.1016/j.electacta.2011.07.059
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发表时间：
2011-10-01
影响因子：
6.6
通讯作者：
Barrado, E.
中科院分区：
文献类型：
--
作者：
Castrillejo, Y.;Fernandez, P.;Barrado, E.
这项工作涉及从熔融氯化物中电化学提取钐。通过这种方式，研究了钐离子在钨、铝和铝包钨电极表面的共晶LiCl-KCl中的电化学行为。在钨惰性电极上，Sm(III) 的电还原仅发生在一个可溶-可溶电化学步骤 Sm(III)/Sm(II) 中。在电化学窗口内没有观察到电化学系统 Sm(II)/Sm(0)，因为 Li(I) 离子从溶剂中预先还原，这抑制了从此类基材上的盐中电萃取 Sm 物质。与熔体接触的 Sm 金属根据反应生成 Li(0)：Sm(0) + 2Li(I) Sm(II) + 2Li(0)。相反，在反应性 Al 电极上，在电活性范围内观察到电化学系统 Sm(II)/Sm(0)。氧化还原电对的电位变化是由于界面处形成Sm-Al合金而导致金属相中Sm活性降低而引起的。研究了金属间化合物的形成机制，该熔体包含：(i) 使用 W 和 Al 涂层的钨电极，同时包含 Sm(III) 和 Al(III) 离子，以及 (ii) 使用 Al 电极的 Sm(III) 离子。通过 X 射线衍射和扫描电子显微镜 (SEM) 以及能量色散 X 射线光谱 (EDS) 对恒电位电解后的样品进行分析，可以鉴定 Al3Sm 和 Al2Sm。 (C) 2011 Elsevier Ltd. 保留所有权利。
This work concerns the electrochemical extraction of samarium from molten chlorides. In this way, the electrochemical behaviour of samarium ions has been investigated in the eutectic LiCl-KCl at the surface of tungsten, aluminium and aluminium coated tungsten electrodes. On a W inert electrode the electro-reduction of Sm(III) takes place in only one soluble-soluble electrochemical step Sm(III)/Sm(II). The electrochemical system Sm(II)/Sm(0) has not been observed within the electrochemical window, because of the prior reduction of Li(I) ions from the solvent, which inhibits the electro-extraction of Sm species from the salt on such a substrate. Sm metal in contact with the melt react to give Li(0) according to the reaction: Sm(0) + 2Li(I) Sm(II) + 2Li(0).On the contrary, on reactive Al electrodes the electrochemical system Sm(II)/Sm(0) was observed within the electroactive range. The potential shift of the redox couple is caused by the decrease of Sm activity in the metal phase due to the formation of Sm-Al alloys at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sm(III) and Al(III) ions, using W and Al coated tungsten electrodes, and (ii) Sm(III) ions using an Al electrode. Analysis of the samples after potentiostatic electrolysis by X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al3Sm and Al2Sm. (C) 2011 Elsevier Ltd. All rights reserved.