Electrochemical evaluation of the surface of chalcopyrite during dissolution in sulfuric acid solution
Electrochemical evaluation of the surface of chalcopyrite during dissolution in sulfuric acid solution
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DOI：
10.1016/j.electacta.2010.03.052
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发表时间：
2010-07
影响因子：
6.6
通讯作者：
A. Ghahremaninezhad;E. Asselin;D. G. Dixon
中科院分区：
文献类型：
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作者：
A. Ghahremaninezhad;E. Asselin;D. G. Dixon
研究了块状黄铜矿电极（98.1%黄铜矿，1.9%菱铁矿）在0.5M硫酸溶液中的溶解。施加不同的阳极电位，并通过EIS，电位动力学和Mott-Schottky技术观察电极的行为。在开路电位（约- 235mV vs. MSE）下的电化学阻抗谱研究证明了电极表面存在薄层。该层相对于MSE稳定到100mV，根据先前的研究报告，假设该层为Cu1−xFe1−yS2（y》x）。通过增加电势到100-300mV vs. MSE范围，先前形成的层部分溶解，在表面形成第二层（Cu1−x−zS2）。在低电位扫描速率（0.05 mv−1）下，两层均表现出被动层的特征，而在高扫描速率下，两层表现出伪被动层的特征。然而，在300-420mV vs. MSE电位范围内，这两层表面层都溶解了，电极开始主动溶解。电势的进一步增大导致cu层的形成，阻碍了电极的溶解速度。cu的形成伴随着Fe2(SO4)3的形成，后者可能在高电位（约750mV vs. MSE）下作为黄铁矾的成核前体。黄钾铁矾在电极表面的沉淀阻碍了黄铜矿在高电位下的溶解。在每个电位范围内建立不同的等效电化学回路模型，并将模型回归结果与EIS实验结果进行比较，确定黄铜矿溶解顺序。
The dissolution of a massive chalcopyrite electrode (98.1% chalcopyrite, 1.9% siderite) was studied in 0.5M sulfuric acid solution. Different anodic potentials were applied and the behavior of the electrode was observed by means of EIS, potentiodynamic, and Mott–Schottky techniques. Electrochemical impedance spectroscopy studies at open circuit potential (around −235mV vs. MSE) proved the existence of a thin surface layer on the electrode. This layer was stable up to 100mV vs. MSE and was assumed to be Cu1−xFe1−yS2(y≫x) based on reports from previous studies. By increasing the potential to the range of 100–300mV vs. MSE, the previously formed layer partially dissolved and a second layer (Cu1−x−zS2) formed on the surface. Both of the layers showed the characteristics of passive layers at low potentiodynamic scan rate (0.05mVs−1) while at high scan rates they acted like pseudo-passive layers. However, in the potential range of 300–420mV vs. MSE, both of these surface layers dissolved and active dissolution of the electrode started. Further increase in potential caused the formation of a CuS layer which hindered the dissolution rate of the electrode. The formation of CuS is concomitant with Fe2(SO4)3formation and the latter may act as a nucleation precursor for jarosite at higher potentials (around 750mV vs. MSE). Jarosite precipitation on the electrode surface hindered the dissolution of chalcopyrite at higher potentials. Different equivalent electrochemical circuits were modeled for each potential range and the model regression results compared with the experimental results of EIS to determine the proposed sequence of chalcopyrite dissolution.