Abstract The effect of lead ions on the dissolution behaviour of gold, thiosulfate, and Cu(en)22+ complex consumption in the Cu2+ − ethylenediamine (en) - S2O32− system has been investigated. Leaching experiments combined with X-ray photoelectron spectroscopy (XPS) analyses showed that the addition of an appropriate concentration of lead ions to the Cu2+- ethylenediamine (en) - S2O32− system facilitates the formation of a part of spotted PbO2 on the surface of the gold foils, which promotes the dissolution of gold, and also prevents the additional consumption of the thiosulfate and Cu(en)22+ complex. The Eh-pH diagram analysis of the system showed that the E(PbO2 / Pb2+) in the system decreased with the increase in lead ion concentration, and that the higher concentration of the lead ions in the system favoured the formation of PbO2. The cyclic voltammetry curves measured using a gold foil which was leached in higher concentration lead ion system as the working electrode in the leaching solution, indicate a significant PbO2 reduction peak. Furthermore, a deposition peak indicating that a part of PbO2 was formed on the gold foil after leaching in the system with the addition of lead was also observed. The Pb2+ in the leaching solution can also form PbO2, and the PbO2 deposition peak and reduction peak of the gold foil electrode after the leaching of lead ions system for 24 h were the most significant. The results of leaching experiments on Au-PbO2 electrode prepared by electrochemical deposition showed that covering a part of PbO2 on the gold foil can promote the dissolution of gold and increase its rate of dissolution. The mechanism of the appropriate concentration lead ions and gold foils in the Cu2+ − en - S2O32− gold leaching system would form many PbO2/Au micro battery is proposed. These micro batteries further improve the dissolution of gold in this system.

中文翻译：

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铅离子对 Cu2+ - en - S2O32− 体系中金溶解的影响

摘要 研究了铅离子对 Cu2+ - 乙二胺 (en) - S2O32- 体系中金、硫代硫酸盐和 Cu(en)22+ 络合物消耗的溶解行为的影响。结合 X 射线光电子能谱 (XPS) 分析的浸出实验表明，向 Cu2+-乙二胺 (en)-S2O32- 体系中添加适当浓度的铅离子有助于在表面形成部分点状 PbO2。金箔，促进金的溶解，也防止硫代硫酸盐和 Cu(en)22+ 复合物的额外消耗。体系的Eh-pH图分析表明体系中的E(PbO2 / Pb2+)随着铅离子浓度的增加而降低，体系中较高的铅离子浓度有利于PbO2的形成。使用在较高浓度铅离子系统中浸出的金箔作为浸出液中的工作电极测量的循环伏安曲线表明显着的 PbO2 还原峰。此外，还观察到在加入铅的体系中浸出后，在金箔上形成了部分PbO2的沉积峰。浸出液中的Pb2+也能形成PbO2，铅离子系统浸出24h后金箔电极的PbO2沉积峰和还原峰最为显着。电化学沉积法制备的Au-PbO2电极浸出实验结果表明，在金箔上覆盖部分PbO2可以促进金的溶解，提高其溶解速度。提出了适当浓度的铅离子和金箔在Cu2+ - en - S2O32- 金浸出体系中形成许多PbO2/Au 微型电池的机理。这些微型电池进一步改善了该系统中金的溶解。