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首页> 外文期刊>Environmental Science & Technology >Molecular Dynamics Simulations of Uranyl and Uranyl Carbonate Adsorption at Aluminosilicate Surfaces
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Molecular Dynamics Simulations of Uranyl and Uranyl Carbonate Adsorption at Aluminosilicate Surfaces

机译：铝硅酸盐表面吸附铀酰和碳酸铀酯的分子动力学模拟

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摘要

Adsorption at mineral surfaces is a critical factor controlling the mobility of uranium(Ⅵ) in aqueous environments. Therefore, molecular dynamics (MD) simulations were performed to investigate uranyl(Ⅵ) adsorption onto two neutral aluminosilicate surfaces, namely, the orthoclase (001) surface and the octahedral aluminum sheet of the kaolinite (001) surface. Although uranyl preferentially adsorbs as a bidentate inner-sphere complex on both surfaces, the free energy of adsorption on the orthodase surface (-15 kcal mol~(-1)) is significantly more favorable than that at the kaolinite surface (-3 kcal mol~(-1)), which is attributed to differences in surface functional groups and the ability of the orthodase surface to release a surface potassium ion upon uranyl adsorption. The structures of the adsorbed complexes compare favorably with X-ray absorption spectros- copy results. Simulations of the adsorption of uranyl complexes with up to three carbonate ligands revealed that uranyl complexes coordinated to up to two carbonate ions are stable on the orthodase surface whereas uranyl carbonate surface complexes are unfavored at the kaolinite surface. Combining the MD-derived equilibrium adsorption constants for orthodase with aqueous equilibrium constants for uranyl carbonate species indicates the presence of adsorbed uranium complexes with one or two carbonates under alkaline conditions, in support of current uranium(Ⅵ) surface complexation models.
机译：矿物表面的吸附是控制铀在水中环境中迁移率的关键因素。因此，进行了分子动力学（MD）模拟，以研究铀酰（Ⅵ）吸附在两个中性铝硅酸盐表面上，即原石酶（001）表面和高岭石（001）表面的八面铝板。尽管铀酰在两个表面上优先以双齿内球络合物的形式吸附，但在原酶表面上的吸附自由能（-15 kcal mol〜（-1））比在高岭石表面上的吸附自由能（-3 kcal mol）更好。 〜（-1）），这归因于表面官能团的差异以及原酶表面在铀酰吸附后释放表面钾离子的能力。吸附的配合物的结构与X射线吸收光谱复制结果相比具有优势。对具有多达三个碳酸根配体的铀酰复合物的吸附模拟表明，与多达两个碳酸根离子配位的铀酰复合物在原酶表面上是稳定的，而碳酸铀酰表面复合物在高岭石表面上是不利的。将原酶的MD衍生平衡吸附常数与碳酸铀酰物质的水平衡常数相结合，表明在碱性条件下，存在铀或六价碳酸盐的铀配合物存在，以支持当前的铀（Ⅵ）表面络合模型。

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  • 来源
    《Environmental Science & Technology》 |2014年第7期|3899-3907|共9页
  • 作者

    Sebastien Kerisit; Chongxuan Liu;

  • 作者单位

    Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States;

    Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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