The effect of As, Co, and Ni impurities on pyrite oxidation kinetics: Batch and flow-through reactor experiments with synthetic pyrite
The effect of As, Co, and Ni impurities on pyrite oxidation kinetics: Batch and flow-through reactor experiments with synthetic pyrite
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DOI：
10.1016/j.gca.2008.02.003
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发表时间：
2008-04-01
影响因子：
5
通讯作者：
Savage, Kaye
中科院分区：
文献类型：
--
作者：
Lehner, Stephen;Savage, Kaye
使用 As、Co 或 Ni 杂质合成且未添加杂质的黄铁矿样品在 1 mM 三价铁存在下、pH 2 下，在间歇式和混合流通式反应器中进行氧化。来自每个掺杂剂群体的六个样品用于提供统计上稳健的比较；还包括来自科罗拉多州莱德维尔（主要杂质铅、砷、铋、银、锌）和意大利厄尔巴岛（钴、砷）的两个天然样品。在每个实验中，监测三个反应进程变量：三价铁、二价铁和硫酸盐。含有杂质的黄铁矿样品的平均氧化速率比未掺杂的样品快，其中砷和钴掺杂的黄铁矿具有最高的速率。 As、Co 和 Ni 根据其在固体样品中的浓度释放到溶液中。由于间歇式反应器实验中的浓度趋于保持恒定，而 Co 和 Ni 的浓度随着时间的推移而增加。根据间歇式反应器实验计算出的初始速率比根据混合流通式反应器实验计算出的稳态速率更快。使用硫酸盐计算的表观速率比使用三价铁和二价铁计算的表观速率更快，反映了溶液中二价铁被溶解氧氧化。结果表明，黄铁矿中的杂质确实有助于其反应性，这与使用电化学方法的研究一致。具有不同杂质的黄铁矿样品之间的氧化速率差异可能太小，不足以保证在环境建模应用中明确考虑，但对于理解黄铁矿氧化机制和半导体特性很重要。 (C) 2008 Elsevier Ltd. 保留所有权利。
Pyrite samples synthesized with As, Co, or Ni impurities and without added impurities were oxidized in batch and mixed flow-through reactors in the presence of 1 mM ferric iron, at pH 2. Six samples from each dopant population were used to provide a statistically robust comparison; two natural samples from Leadville, CO (major impurities Pb, As, Bi, Ag, Zn) and Elba, Italy (Co, As) were also included. In each experiment, three reaction progress variables were monitored: ferric iron, ferrous iron, and sulfate. The pyrite samples with impurities have average oxidation rates that are faster than the undoped samples, with As- and Co-doped pyrite having the highest rates. As, Co, and Ni were released to solution in accordance with their concentrations in the solid samples. As concentrations in the batch reactor experiments tended to remain constant, in contrast to Co and Ni, which increased over time. Initial rates, calculated from the batch reactor experiments, were faster than the steady-state rates calculated from the mixed flow-through reactor experiments. Apparent rates calculated using sulfate were faster than apparent rates calculated using ferric and ferrous iron, reflecting oxidation of ferrous iron in solution by dissolved oxygen. The results imply that impurities in pyrite do contribute to its reactivity, in agreement with studies using electrochemical methods. Oxidation rate differences among pyrite samples with different impurities are probably too small to warrant explicit consideration in environmental modeling applications, but are important to understanding pyrite oxidation mechanisms and semiconducting properties. (C) 2008 Elsevier Ltd. All rights reserved.