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首页> 外文期刊>Soil Science Society of America Journal >Selenite Adsorption Mechanisms on Pure and Coated Montmorillonite: An EXAFS and XANES Spectroscopic Study
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Selenite Adsorption Mechanisms on Pure and Coated Montmorillonite: An EXAFS and XANES Spectroscopic Study

机译：纯蒙脱土和蒙脱土对亚硒酸盐的吸附机理：EXAFS和XANES光谱研究

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Selenite (SeO32–) is an oxyanion of environmental importance due to its toxicity to animals at higher concentrations, notably waterfowl and grazing animals. Sorption of SeO32– with mineral phases typically controls the movement and bioaccessibility of SeO32– in soils and sediments. Previous studies have successfully utilized synchrotron-based Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) spectroscopy to determine SeO32– bonding mechanisms on Fe and Mn oxides, but the direct evidence of SeO32– surface complexation mechanisms on important mineral phases such as Al hydroxide and aluminosilicate minerals is still lacking. In this study both EXAFS and XANES spectroscopy was conducted on aqueous SeO32– solutions and on a variety of Al-bearing sorption samples at pH 4.5. The sorbents chosen were a hydroxyaluminosilicate (HAS) polymer, a hydroxyaluminum (HYA) polymer, montmorillonite, and both HYA and HAS coated montmorillonite. For SeO32– sorption on montmorillonite, only bidentate binuclear inner-sphere complexation was observed. For the hydroxyaluminum and hydroxyaluminosilicate polymers, a mixture of outer-sphere and bidentate binuclear inner-sphere was observed. When montmorillonite was coated with either HYA or HAS polymers then adsorption behavior was intermediate between that of the mineral and the pure polymer. Since temperate soils often contain aluminum-hydroxy and aluminosilicate coated minerals rather than discrete Al hydroxide minerals and pristine clay surfaces, the adsorption mechanisms observed on these coated surfaces are more realistic of the natural environment than sorption on pure minerals.
机译：亚硒酸盐（SeO 3 2 – ）是一种对环境具有重要意义的含氧阴离子 ，因为它对较高浓度的动物具有毒性，特别是 水禽和放牧动物。矿物质相与 对SeO 3 2 – 的吸附通常控制SeO 3 <的运动和生物可及性 / sub> 2 – 在土壤和沉积物中。先前的研究 成功地利用了基于同步加速器的扩展X射线吸收 精细结构（EXAFS）和近边缘结构的X射线吸收 （XANES）光谱法确定SeO 3 2-在Fe和Mn氧化物上的键合机理 ，但是SeO 3 的直接证据在重要的矿物相如氢氧化铝和铝硅酸盐矿物上仍然缺乏 2 – 的表面络合机制。 研究是在含水SeO 3 2-溶液和各种含铝 上进行EXAFS和XANES光谱学研究>在pH 4.5时吸附样品。选择的吸附剂为羟基铝硅酸盐（HAS）聚合物，羟基铝（HYA）聚合物，蒙脱石， 以及HYA和HAS包覆的蒙脱石。对于在蒙脱石上吸附的SeO 3 2 – ，仅观察到双齿双核内球 的复合。对于羟基铝和羟基铝硅酸盐 聚合物，观察到外球和双齿双核 内球的混合物。当蒙脱土用HYA或HAS聚合物涂覆时，吸附行为介于矿物和纯聚合物之间。由于温带土壤通常包含铝羟基和铝硅酸盐涂覆的矿物，而不是离散的氢氧化铝矿物和原始的粘土表面，因此在这些表面观察到的吸附机理涂层 在自然环境中比在纯矿物上吸附 更真实。

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    《Soil Science Society of America Journal》 |2006年第1期|192-203|共12页
  • 作者

    Derek Peak; U. K. Saha; P. M. Huang;

  • 作者单位

    Dep. of Soil Science, Univ. of Saskatchewan, 51 Campus Dr., Saskatoon SK S7N 5A8 Canada;

    Dep. of Soil Science, Univ. of Saskatchewan, 51 Campus Dr., Saskatoon SK S7N 5A8 Canada;

    Dep. of Soil Science, Univ. of Saskatchewan, 51 Campus Dr., Saskatoon SK S7N 5A8 Canada;

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