Electrochemical oxidation of pyrite (FeS2) in aqueous electrolytes
Electrochemical oxidation of pyrite (FeS2) in aqueous electrolytes
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DOI：
10.1016/s0022-0728(99)00261-2
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发表时间：
1999-08-13
影响因子：
4.5
通讯作者：
Brandon, NP
中科院分区：
文献类型：
--
作者：
Kelsall, GH;Yin, Q;Brandon, NP
采用电化学技术、原位傅里叶变换红外光谱（FTIR）、非原位x射线光电子能谱（XPS）和离子色谱（IC）研究了黄铁矿（FeS2）在水溶液中的电化学氧化。结果表明，当黄铁矿与SCE在1 M HCl溶液中以大于或等于30 mV s（-1）的扫描速率在- 0.35 ~ 0.25 V电位区极化时，氧化还原过程为可逆的电化学吸附/解吸过程。而当扫描速率小于或等于10 mV s（-1）时，黄铁矿表面发生大量氧化，并变得部分不可逆。n型黄铁矿在很宽的电位范围内的氧化速率非常有限，这可能是由于其半导体特性，或者是施加电位的主要部分落在空间电荷区而不是亥姆霍兹层。黄铁矿的电化学氧化是一个复杂的串联和平行反应步骤，最终生成Fe2+/Fe3+和S/S2O32-/HSO4-，取决于pH和电位。利用能带和分子轨道理论，提出并讨论了这一过程的机理。(C) 1999 Elsevier Science S.A.版权所有
Electrochemical oxidation of pyrite (FeS2) in aqueous electrolytes has been investigated using electrochemical techniques, in situ Fourier transform infrared spectroscopy (FTIR), ex situ X-ray photoelectron spectroscopy (XPS) and ion chromatography (IC). The results show that when pyrite is polarised in the potential region of - 0.35 to 0.25 V versus SCE in 1 M HCl at sweep rates greater than or equal to 30 mV s(-1), the redox process is a reversible electrochemical adsorption/desorption. whereas at sweep rates less than or equal to 10 mV s(-1) substantial oxidation of the pyrite surface occurs and becomes partially irreversible. The very limited oxidation rate of n-type pyrite over a wide range of potentials may be attributed to its semiconducting properties, or the main part of the applied potential falling across the space charge region rather than the Helmholtz layer. The electrochemical oxidation of pyrite involves a complex series and parallel reaction steps, ultimately producing Fe2+/Fe3+ and S/S2O32-/HSO4-, depending on pH and potential. A mechanism for this process is proposed and discussed using energy band and molecular orbital theories. (C) 1999 Elsevier Science S.A. All rights reserved.