Fe(II)-Mediated Reduction and Repartitioning of Structurally Incorporated Cu, Co, and Mn in Iron Oxides
Fe(II)-Mediated Reduction and Repartitioning of Structurally Incorporated Cu, Co, and Mn in Iron Oxides
复制标题
DOI：
10.1021/es302236v
复制
发表时间：
2012-10-16
影响因子：
11.4
通讯作者：
Catalano, Jeffrey G.
中科院分区：
文献类型：
--
作者：
Frierdich, Andrew J.;Catalano, Jeffrey G.
Fe（II）在Fe（III）氧化物表面对微量元素和污染物的还原是有据可查的。然而，Fe（II）水溶液对氧化还原活性微量元素结构纳入氧化铁的命运的影响是未知的。在这里，我们调查的命运的氧化还原活性元素在Fe（II）激活重结晶的铜，钴，锰取代针铁矿和赤铁矿。在所有材料暴露于Fe（II）水溶液时，相对于在无Fe（II）流体中的反应，Cu、Co和Mn向溶液的释放增强。微量元素的释放量随pH值的增加时，Fe（11）的存在，但随pH值的增加，在没有Fe（II）的情况下减少。钴和锰从针铁矿释放预测以及使用二阶动力学模型，与释放的氧化还原惰性元素，如镍和锌。然而，铜释放和钴和锰释放从赤铁矿需要两个速率的总和，以充分模拟动力学数据。更大的吸收Fe（II）的Cu-，Co-和Mn-取代的铁氧化物相对于类似物只含有氧化还原惰性元素表明，净Fe（II）氧化发生。通过X射线吸收近边结构光谱证实了在pH 7.0-7.5下与Fe（II）反应后所有材料中的Cu、Co和Mn的还原。这项工作表明，氧化还原敏感的元素结构纳入铁氧化物减少，并重新分配到流体在Fe（II）介导的重结晶。这种非生物反应可能与部分微生物和非生物铁还原或含Fe（II）的流体迁移过程中协同操作，从而在水生系统中动员结构结合的污染物和微量营养素。
The reduction of trace elements and contaminants by Fe(II) at Fe(III) oxide surfaces is well documented. However, the effect of aqueous Fe(II) on the fate of redox-active trace elements structurally incorporated into iron oxides is unknown. Here, we investigate the fate of redox-active elements during Fe(II)-activated recrystallization of Cu-, Co-, and Mn-substituted goethite and hematite. Enhanced release of Cu, Co, and Mn to solution occurs upon exposure of all materials to aqueous Fe(II) relative to reactions in Fe(II)-free fluids. The quantity of trace element release increases with pH when Fe(11) is present but decreases with increasing pH in the absence of Fe(II). Co and Mn release from goethite is predicted well using a second-order kinetic model, consistent with the release of redox-inactive elements such as Ni and Zn. However, Cu release and Co and Mn release from hematite require the sum of two rates to adequately model the kinetic data. Greater uptake of Fe(II) by Cu-, Co-, and Mn-substituted iron oxides relative to analogues containing only redox-inactive elements suggests that net Fe(II) oxidation occurs. Reduction of Cu, Co, and Mn in all materials following reaction with Fe(II) at pHs 7.0-7.5 is confirmed by X-ray absorption near-edge structure spectroscopy. This work shows that redox-sensitive elements structurally incorporated within iron oxides are reduced and repartitioned into fluids during Fe(II)-mediated recrystallization. Such abiotic reactions likely operate in tandem with partial microbial and abiotic iron reduction or during the migration of Fe(II)-containing fluids, mobilizing structurally bound contaminants and micronutrients in aquatic systems.