Adsorption mechanism of selenium(VI) onto maghemite
Adsorption mechanism of selenium(VI) onto maghemite
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DOI：
10.1016/j.gca.2012.09.048
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发表时间：
2013-02-15
影响因子：
5
通讯作者：
Reuther, H.
中科院分区：
文献类型：
--
作者：
Jordan, N.;Ritter, A.;Reuther, H.
在这项研究中，磁赤铁矿（γ-Fe 2 O3）对硒（VI）的吸附性能进行了研究，首次在宏观和分子水平。使用批实验，我们发现保留反应非常快。pH值和离子强度的增加导致硒（VI）的吸附减少。电泳迁移率的测量结果表明，硒（VI）的吸附磁赤铁矿的等电点没有显着的影响。这些宏观结果强烈地表明在所研究的pH范围（3.5-8.0）内形成了外层复合物。在分子水平上，吸附的表面物种的结构，阐明了原位使用衰减全反射傅里叶变换红外（ATR FT-IR）光谱和扩展X射线吸收精细结构（EXAFS）光谱。ATR FT-IR结果表明形成的外层配合物显示出意想不到的双齿对称性，这可能揭示了实际上广泛使用的分类的阴离子物种的内部和外层配位缺乏准确性。EXAFS结果表明，除了外层复合物，也有一个小的（15%）的贡献，在双核角共享几何的内层复合物。(C)2012爱思唯尔有限公司保留所有权利。
In this study, the sorption properties of maghemite (gamma-Fe2O3) towards selenium(VI) were studied for the first time both on the macroscopic and the molecular level. Using batch experiments, we found that the retention reaction was very fast. Both increase of pH and ionic strength led to a decrease of selenium(VI) sorption. Electrophoretic mobility measurements showed that selenium(VI) sorption had no significant effect on the isoelectric point of maghemite. These macroscopic results strongly suggested the formation of outer-sphere complexes across the investigated pH range (3.5-8.0). At the molecular level, the structure of the sorbed surface species was elucidated in situ using Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) spectroscopy and Extended X-ray Absorption Fine-Structure (EXAFS) spectroscopy. The ATR FT-IR results suggested the formation of outer-sphere complexes showing an unexpected bidentate symmetry, which possibly revealed the lack of accuracy of the actual widely-used classification of inner-and outer-sphere coordination for anionic species. EXAFS results revealed, that in addition to outer-sphere complexes, there is also a small (15%) contribution of an inner-sphere complex in binuclear corner-sharing geometry present. (C) 2012 Elsevier Ltd. All rights reserved.