As(V) and As(III) reactions on pristine pyrite and on surface-oxidized pyrite.
As(V) and As(III) reactions on pristine pyrite and on surface-oxidized pyrite.
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DOI：
10.1016/j.jcis.2012.08.019
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发表时间：
2012-12
影响因子：
9.9
通讯作者：
Fenglong Sun;B. Dempsey;K. Osseo-Asare
中科院分区：
文献类型：
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作者：
Fenglong Sun;B. Dempsey;K. Osseo-Asare
研究了As（III）和As(V)与黄铁矿的反应，分别采用原始黄铁矿（在严格缺氧条件下生成并反应，PO2<10−8atm）和表面氧化黄铁矿（在缺氧条件下生成，暴露于空气中，然后在严格缺氧条件下储存和反应）。表面氧化黄铁矿的结果与先前报道的砷-黄铁矿的结果相似。然而，As（III）吸附在原始黄铁矿上的pH值范围比表面氧化黄铁矿大，As(V)吸附在原始黄铁矿上的pH值范围比表面氧化黄铁矿小，吸附在原始黄铁矿上的As(V)被还原为As(III)，而吸附的As(V)不被表面氧化黄铁矿还原。原始黄铁矿对As(V)的还原为一级还原，释放出Fe(II)，并氧化硫。提出的As(V)氧化黄铁矿的机理与已发表的o2氧化黄铁矿的机理相似，并对其速率进行了比较。结果可用于预测连续缺氧环境下黄铁矿上As(V)和As（III）的去除率，或间歇缺氧环境下黄铁矿上As(V)和As（III）的去除率。如果商业或生产的黄铁矿被用作原始黄铁矿的替代品，则需要严格的清理和严格缺氧条件的持续维护。
Reactions of As(III) and As(V) with pyrite were investigated using pristine pyrite (produced and reacted in a rigorously anoxic environment with PO2<10−8atm) and using surface-oxidized pyrite (produced under anoxic conditions, exposed to air, then stored and reacted under rigorously anoxic conditions). Results with surface-oxidized pyrite were similar to previously reported arsenic-pyrite results. However As(III) adsorbed over a broader pH range on pristine pyrite than on surface-oxidized pyrite, As(V) adsorbed over a narrower pH range on pristine pyrite than on surface-oxidized pyrite, and adsorbed As(V) on pristine pyrite was reduced to As(III) but adsorbed As(V) was not reduced with surface-oxidized pyrite. Reduction of As(V) with pristine pyrite was first-order in total As(V), Fe(II) was released, and sulfur was oxidized. The proposed mechanism for pyrite oxidation by As(V) was similar to the published mechanism for oxidation by O2and rates were compared. The results can be used to predict the removals of As(V) and As(III) on pyrite in continuously anoxic environments or on pyrite in intermittently oxic/anoxic environments. Rigorous cleanup and continuous maintenance of strictly anoxic conditions are required if commercial or produced pyrites are to be used as surrogates for pristine pyrite.