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Atomistic Simulations of Uranium Incorporation into Iron (Hydr)Oxides

机译：铀掺入氧化铁中的原子模拟

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摘要

Atomistic simulations were carried out to characterize the coordination environments of U incorporated in three Fe-(hydr) oxide minerals: goethite, magnetite, and hematite. The simulations provided information on U-O and U-Fe distances, coordination numbers, and lattice distortion for U incorporated in different sites (e.g., unoccupied versus occupied sites, octahedral versus tetrahedral) as a function of the oxidation state of U and charge compensation mechanisms (i.e., deprotonation, vacancy formation, or reduction of Fe(lll) to Fe(II)). For goethite, deprotonation of first shell hydroxyls enables substitution of U for Fe(lll) with a minimal amount of lattice distortion, whereas substitution in unoccupied octahedral sites induced appreciable distortion to 7-fold coordination regardless of U oxidation states and charge compensation mechanisms. Importantly, U-Fe distances of ~3.6 A were associated with structural incorporation of U and cannot be considered diagnostic of simple adsorption to goethite surfaces. For magnetite, the octahedral site accommodates U(V) or U(VI) with little lattice distortion. U substituted for Fe(lll) in hematite maintained octahedral coordination in most cases. In general, comparison of the simulations with available experimental data provides further evidence for the structural incorporation of U in iron (hydr) oxide minerals.
机译：进行了原子模拟，以表征掺入三种铁（水）氧化物矿物中的铀的配位环境：针铁矿，磁铁矿和赤铁矿。模拟提供了有关UO和U-Fe距离，配位数以及掺入不同位点（例如，空位与占据位点，八面体与四面体）的U随U的氧化态和电荷补偿机制的信息（即去质子化，空位形成或Fe（III）还原为Fe（II））。对于针铁矿，第一壳羟基的去质子化使U以最小的晶格畸变取代了Fe（III），而在未占据的八面体位点中的取代则引起明显的畸变至7倍配位，无论U氧化态和电荷补偿机制如何。重要的是，〜3.6 A的U-Fe距离与U的结构结合有关，不能视为诊断容易吸附到针铁矿表面。对于磁铁矿，八面体位点可容纳U（V）或U（VI），且晶格畸变很小。在大多数情况下，U替代赤铁矿中的Fe（III）保持八面体配位。通常，将模拟与可用的实验数据进行比较，为铀在铁（水）氧化物矿物中的结构结合提供了进一步的证据。

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  • 来源
    《Environmental Science & Technology》 |2011年第7期|p.2770-2776|共7页
  • 作者

    Sebastien Kerisit; Andrew R. Felmy; Eugene S. Ilton;

  • 作者单位

    Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States;

    Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States;

    Chemical and Materials 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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