Institute of Geosciences, Friedrich-Schiller-University Jena, 07745 Jena, Germany.
Environ Sci Technol. 2013 Aug 20;47(16):9140-7. doi: 10.1021/es305182c. Epub 2013 Aug 2.
Hematite (α-Fe2O3) is one of the most common iron oxides and a sink for the toxic metalloid arsenic. Arsenic can be immobilized by adsorption to the hematite surface; however, the incorporation of As in hematite was never seriously considered. In our study we present evidence that, besides adsorption, the incorporation of As into the hematite crystals can be of great relevance for As immobilization. With the coupling of nanoresolution techniques and X-ray absorption spectroscopy the presence of As (up to 1.9 wt %) within the hematite crystals could be demonstrated. The incorporated As(5+) displays a short-range order similar to angelellite-like clusters, epitaxially intergrown with hematite. Angelellite (Fe4As2O11), a triclinic iron arsenate with structural relations to hematite, can epitaxially intergrow along the (210) plane with the (0001) plane of hematite. This structural composite of hematite and angelellite-like clusters represents a new immobilization mechanism and potentially long-lasting storage facility for As(5+) by iron oxides.
赤铁矿（α-Fe2O3）是最常见的氧化铁之一，也是有毒类金属砷的汇。砷可以通过吸附到赤铁矿表面而固定；然而，将砷掺入赤铁矿晶体中从未被认真考虑过。在我们的研究中，我们提供的证据表明，除了吸附之外，砷掺入赤铁矿晶体中对于砷的固定具有重要意义。通过纳米分辨率技术和 X 射线吸收光谱的结合，证明了赤铁矿晶体中存在砷（高达 1.9wt%）。掺入的 As(5+) 表现出类似于似 Ange11e1lite 样簇的短程有序，与赤铁矿外延共生长。 Ange11e1lite（Fe4As2O11）是一种具有与赤铁矿结构关系的三方铁砷酸盐，可以沿（210）平面与赤铁矿的（0001）平面外延共生长。这种赤铁矿和 Ange11e1lite 样簇的结构复合材料代表了一种新的砷（5+）固定机制，以及铁氧化物潜在的长效砷（5+）存储设施。
