In this research, the ethylamine-ammonium-sulfate novel system is electrochemically studied to comprehend the governing reaction mechanism for silver leaching. The effect of using ethylamine (EA) instead of monoethanolamine (MEA) on silver leaching kinetics is presented in this paper. The study was complemented with thermodynamic modelling, electrochemical tests (Tafel, linear voltammetry and OCP), surface characterization techniques (FESEM-EDS) and leaching tests using H2O2 as an oxidizing agent. The results revealed that EA and ammoniacal species can compete to dissolve silver as the complexes Ag EA2+ and Ag NH32+ at pH 10.2. The Tafel analysis showed that silver oxidation is strongly dependent on the EA concentration, and the rate law of the rate determining step of silver dissolution is of first order with respect to EA concentration. The electrochemical tests permitted to elucidate the main kinetic difference between the MEA and EA containing systems, i.e., EA does not work as a catalyst for silver dissolution. However, EA can be promising to perform the co-dissolution of silver and can be an interesting option to perform cathodic pre-treatments of other silver sulfide species. Experiments carried out with carbon paste electrodes containing silver sulfide, revealed that cathodic decomposition of silver sulfide presents significantly higher kinetics than that observed with MEA containing solutions. Finally, silver leaching tests carried out in a batch reactor showed the possibility to dissolve 65 % of silver in 30 min using the EA containing leaching system at room temperature.

中文翻译：

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使用乙胺-硫酸铵-新型系统对银溶解进行机理电化学分析

在这项研究中，对乙胺-铵-硫酸盐新型系统进行了电化学研究，以了解银浸出的控制反应机制。本文介绍了使用乙胺 （EA） 代替单乙醇胺 （MEA） 对银浸出动力学的影响。该研究还辅以热力学建模、电化学测试（Tafel、线性伏安法和 OCP）、表面表征技术 （FESEM-EDS） 和使用 H2O2 作为氧化剂的浸出测试。结果表明，在 pH 值为 10.2 时，EA 和氨物质可以竞争溶解银，因为复合物 Ag EA2+ 和 Ag NH32+。Tafel 分析表明，银氧化强烈依赖于 EA 浓度，并且决定银溶解速率步骤的速率定律相对于 EA 浓度是一阶的。允许阐明含 MEA 和 EA 的系统之间的主要动力学差异的电化学测试，即 EA 不能作为银溶解的催化剂。然而，EA 可以有望进行银的共溶解，并且可以成为对其他硫化银物种进行阴极预处理的有趣选择。使用含有硫化银的碳膏电极进行的实验表明，硫化银的阴极分解表现出明显高于使用含 MEA 的溶液观察到的动力学。最后，在间歇式反应器中进行的银浸出测试表明，在室温下使用含有 EA 的浸出系统可以在 30 分钟内溶解 65 % 的银。