Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790784, Korea.
Environ Sci Technol. 2010 Feb 1;44(3):955-61. doi: 10.1021/es902577y.
In this study we investigated the speciation of the solid-phase As formed by reacting 2 x 10(-4) M As(III) with 1.0 g/L mackinawite and the potential for these sorbed species to be mobilized (released into the aqueous phase) upon exposure to atmospheric oxygen at pH 4.9, 7.1, and 9.1. Before oxygen exposure, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) analyses indicated that As(III) was removed from the aqueous phase by forming As(0), AsS, and surface precipitates as thioarsenites at pH 4.9 and As(0) and thioarsenite surface precipitates at pH 7.1 and 9.1. When oxygen was introduced, XAS analysis indicated that As(0) and the surface precipitates were quickly transformed, whereas AsS was persistent. During intermediate oxygen exposure times, dissolved As increased at pH 4.9 and 7.1 due to the rapid oxidation of As(0) and the slow precipitation of iron (oxyhydr)oxides, the oxidation products of mackinawite. This indicates that oxidative mobilization is a potential pathway for arsenic contamination of water at acidic to neutral pH. The mobilized As was eventually resorbed by forming edge-sharing and double-corner-sharing surface complexes with iron (oxyhydr)oxides.
在这项研究中，我们研究了 2 x 10(-4) M 的 As(III)与 1.0 g/L 的磁黄铁矿反应形成的固相 As 的形态，以及这些被吸附的物质在 pH 值为 4.9、7.1 和 9.1 的大气氧暴露下被迁移（释放到水相）的潜力。在氧气暴露之前，X 射线吸收光谱（XAS）和 X 射线光电子能谱（XPS）分析表明，As(III)通过形成 As(0)、AsS 和硫代砷酸盐表面沉淀物而从水相中去除，在 pH 值为 4.9 和 7.1 的情况下形成 As(0)和硫代砷酸盐表面沉淀物，在 pH 值为 9.1 的情况下形成 As(0)和硫代砷酸盐表面沉淀物。当引入氧气时，XAS 分析表明 As(0)和表面沉淀物很快被转化，而 AsS 则保持持久。在中间氧气暴露时间内，由于 As(0)的快速氧化和磁黄铁矿氧化产物铁（氢氧）氧化物的缓慢沉淀，pH 值为 4.9 和 7.1 的溶解 As 增加。这表明氧化迁移是酸性到中性 pH 值下水砷污染的潜在途径。被迁移的 As 最终通过与铁（氢氧）氧化物形成边共享和双角共享表面络合物而被重新吸收。
