Sorption and speciation of arsenic by zero-valent iron
Sorption and speciation of arsenic by zero-valent iron
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DOI：
10.1016/j.colsurfa.2008.10.033
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发表时间：
2009-09-05
影响因子：
5.2
通讯作者：
Hirajima, T.
中科院分区：
文献类型：
--
作者：
Sasaki, K.;Nakano, H.;Hirajima, T.
通过静态和静态实验研究了零价铁（ZVI）修复地下水过程中砷的吸附和形态变化。在批量测试中，亚砷酸盐被氧化为砷酸盐，砷酸盐通过与作为腐蚀产物的含Fe（III）的化合物共沉淀而被有利地固定，导致As（V）的占主导地位的表面物种。在柱材料后，引入与亚砷酸盐的22孔体积（pvs）的进水，As（III）是占主导地位的ZVI的表面上的所有部分列，而强烈的亚砷酸盐的氧化，特别是在入口附近观察。分析认为，由于ZVI颗粒在大部分底部与高浓度的亚砷酸盐接触时间最长，其表面已经均匀化，腐蚀产物在入口附近的ZVI颗粒上积累最多。XPS的实验结果也支持了这一点，即氧化物的O 1 s峰的相对强度在最底部段最大。XPS结果还表明，砷被固定在ZVI颗粒主要是亚砷酸盐和在较小程度上的砷酸盐。这些观察结果表明，保留机制主要是吸附，而不是还原。地球化学计算结果沿着SEM-EDX表明，砷和砷酸盐主要与含Fe（III）矿物和碳酸盐共沉淀。(C)2008 Elsevier B. V.保留所有权利。
Sorption and speciation of arsenic in groundwater remediation using zero-valent iron (ZVI) was investigated by batch and column experiments. In batch tests, arsenite was oxidized to arsenate which was favorably immobilized by co-precipitation with Fe(III)-bearing compounds as corrosion products, leading to the dominant surface species of As(V). In column materials after introducing influent with arsenite for 22 pore volumes(pvs), As(III) was predominant on the surface of ZVI in all segments of column, while intense oxidation of arsenite to arsenate was observed especially near the inlet. It is considered that the surface of ZVI granules was already uniformed and corrosion products are the most accumulated on ZVI granules near the inlet because ZVI has been contacted with high concentrations of arsenite for the longest time in the most bottom parts. This was also supported by the experimental results of XPS that relative intensity of O 1s peak assigned to oxide was the largest in the most bottom segment. Also XPS results revealed that arsenic was immobilized on ZVI granules mainly as arsenite and to a lesser extent arsenate. These observations suggest that the retention mechanism is primarily sorption rather than reduction. The results of geochemical calculations along with the SEM-EDX suggest that arsenite and arsenate were co-precipitated with mainly Fe(III)-bearing minerals and carbonates. (C) 2008 Elsevier B.V. All rights reserved.