NaCl-KCl共融盐中铅的电化学行为与电解制备

来源期刊:中国有色金属学报(英文版)2020年第9期

论文作者:朱曾丽 刘欢 陈杰双阳 孔辉 徐亮 华中胜 赵卓

文章页码:2568 - 2576

关键词:电化学行为;Pb(II);还原;废铅酸电池;NaCl-KCl共融盐

Key words:electrochemical behavior; Pb(II); reduction; spent lead acid batteries; eutectic NaCl-KCl melt

摘    要:为了开发高效、环境友好的废铅酸电池回收工艺,提出一种基于氯化焙烧和熔盐电解的新型处理方法。首先,通过热力学分析对熔盐法从废铅酸电池中回收铅的可行性进行论证。然后,采用电化学暂态测试方法对700 °C时NaCl-KCl共融盐中Pb(II)在钨电极上的电化学行为进行深入研究。结果表明:Pb(II)在NaCl-KCl熔盐中的还原反应是一步交换2个电子的准可逆过程,且该过程受准可逆扩散控制。最后,于-0.6 V (vs Ag/AgCl)电位下在NaCl-KCl-PbCl2熔盐中进行恒电位电解,所得阴极产物经X射线衍射分析证实为纯Pb。本研究表明,在NaCl-KCl共融盐中电解还原PbCl2制备金属铅是切实可行的,并为熔盐法从废铅酸电池中回收铅的后续研究提供重要理论依据。

Abstract: A novel molten salt extraction process consisting of chlorination roasting and molten salt electrolysis was proposed to develop a more efficient and environmental friendly technology for recovering lead from spent lead acid batteries (LABs). The feasibility of this process was firstly assessed based on thermodynamics fundamentals. The electrochemical behavior of Pb(II) on a tungsten electrode in the eutectic NaCl-KCl melts at 700 °C was then investigated in detail by transient electrochemical techniques. The results indicated that the reduction reaction of Pb(II) in NaCl-KCl melts was a one-step process exchanging two electrons, and it was determined to be a quasi-reversible diffusion-controlled process. Finally, potentiostatic electrolysis was carried out at -0.6 V (vs Ag/AgCl) in the NaCl-KCl-PbCl2 melts, and the obtained cathodic product was identified as pure Pb by X-ray diffraction analysis. This investigation demonstrated that it is practically feasible to produce pure Pb metal by electrochemical reduction of PbCl2 in eutectic NaCl-KCl melts, and has provided important fundamental for the further study on lead recovery from spent LABs via molten salt extraction process.

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