Effect of ammoniacal thiosulfate solution composition on the gold dissolution rate: An electrochemical study

IF 5.5 3区材料科学 Q1 ELECTROCHEMISTRY Electrochimica Acta Pub Date : 2024-11-15 DOI:10.1016/j.electacta.2024.145359

José A. Tamayo, Carolina Ramírez-Sánchez, Jorge A. Calderón

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Abstract

The electrochemical behavior of ammoniacal thiosulfate solutions (S₂O₃^2-- NH3-Cu²⁺ -EDTA) has been studied for varying electrolyte compositions in the gold electro-dissolution. A gold rotating disk electrode (RDE) was employed to measure anodic and cathodic polarization curves in alkaline thiosulfate solutions. Potentiodynamic polarization showed how thiosulfate, ammonia, and copper concentration influence the cathodic and anodic behavior of the electrolyte. Likewise, the influence of oxygen on the electrochemical behavior system was evidenced from the analysis of polarization curves, and using Koutecky – Levich equation (slope of 59.60 mV/decade), it was possible to determine the peroxide pathway for oxygen reduction reaction (ORR) with two-electron transference. Additionally, gold dissolution and thiosulfate degradation were evaluated using the gold foil leaching tests. It was found solutions with a 0.2 mol L^-1 thiosulfate concentration favored the dissolution of gold and by maintaining an adequate ratio between thiosulfate/ammonium (1:3) or thiosulfate/copper (4:1) enable the attainment high gold dissolution and lower degradation of thiosulfate.

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硫代硫酸铵溶液成分对金溶解速率的影响：电化学研究

研究了不同电解质成分的硫代硫酸铵溶液（S2O32--NH3-Cu2+-EDTA）在金电解过程中的电化学行为。使用金旋转盘电极（RDE）测量了碱性硫代硫酸盐溶液中的阳极和阴极极化曲线。电位极化显示了硫代硫酸盐、氨和铜的浓度如何影响电解质的阴极和阳极行为。同样，氧气对电化学行为系统的影响也可以从极化曲线的分析中得到证明，利用库特基-列维奇方程（斜率为 59.60 mV/decade），可以确定氧气还原反应（ORR）的过氧化物途径与双电子转移。此外，还利用金箔浸出试验对金的溶解和硫代硫酸盐降解进行了评估。结果发现，硫代硫酸浓度为 0.2 mol L-1 的溶液有利于金的溶解，而通过保持硫代硫酸/铵（1:3）或硫代硫酸/铜（4:1）之间的适当比例，可以实现较高的金溶解度和较低的硫代硫酸降解度。

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来源期刊

Electrochimica Acta 工程技术-电化学

CiteScore

11.30

自引率

6.10%

发文量

1634

审稿时长

41 days

期刊介绍： Electrochimica Acta is an international journal. It is intended for the publication of both original work and reviews in the field of electrochemistry. Electrochemistry should be interpreted to mean any of the research fields covered by the Divisions of the International Society of Electrochemistry listed below, as well as emerging scientific domains covered by ISE New Topics Committee.