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首页> 外文期刊>Environmental Science & Technology >Technetium Incorporation into Goethite (α-FeOOH): An Atomic-Scale Investigation
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Technetium Incorporation into Goethite (α-FeOOH): An Atomic-Scale Investigation

机译：Go掺入针铁矿（α-FeO​​OH）：原子尺度研究

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摘要

During the processing of low-activity radioactive waste to generate solid waste forms (e.g., glass), technetium-99 (Tc) is of concern because of its volatility. A variety of materials are under consideration to capture Tc from waste streams, including the iron oxyhydroxide, goethite (α-FeOOH), which was experimentally shown to sequester Tc(Ⅳ). This material could ultimately be Incorporated into glass or alternative low-temperature waste form matrices. However, questions remain regarding the incorporation mechanism for Tc(Ⅳ) in goethite, which has implications for predicting the long-term stability of Tc in waste forms under changing conditions. Here, quantum-mechanical calculations were used to evaluate the energy of five different charge-compensated Tc(Ⅳ) incorporation scenarios in goethite. The two most stable incorporation mechanisms involve direct substitution of Tc(Ⅳ) onto Fe(Ⅲ) lattice sites and charge balancing either by removing one nearby H~+ (i.e., within 5 A) or by creating an Fe(Ⅲ) vacancy when substituting 3 Tc(Ⅳ) for 4 Fe(Ⅲ), with the former being preferred over the latter relative to gas-phase ions. When corrections for hydrated references phases are applied, the Fe(Ⅲ)-vacancy mechanism becomes more energetically competitive. Calculated incorporation energies and optimized bond lengths are presented. Proton movement is observed to satisfy undercoordinated bonds surrounding Fe(Ⅲ)-vacandes in the goethite structure.
机译：在处理低放射性放射性废物以产生固体废物形式（例如玻璃）的过程中，tech 99（Tc）由于易挥发而受到关注。正在考虑从废物流中捕获Tc的各种材料，包括羟基氧化铁，针铁矿（α-FeO​​OH），这些材料已通过实验证明可以隔离Tc（Ⅳ）。该材料最终可以掺入玻璃或其他低温废物形式的基质中。然而，针铁矿中Tc（Ⅳ）的掺入机理仍然存在疑问，这对于预测不断变化的条件下废料中Tc的长期稳定性具有重要意义。在这里，使用量子力学计算来评估针铁矿中五种不同的电荷补偿的Tc（Ⅳ）结合场景的能量。两种最稳定的掺入机制包括将Tc（Ⅳ）直接取代到Fe（Ⅲ）晶格位点上，以及通过除去附近的H〜+（即5 A内）或在取代时产生Fe（Ⅲ）空位来实现电荷平衡。 3 Tc（Ⅳ）表示4 Fe（Ⅲ），相对于气相离子，前者优先于后者。当对水合参比物进行校正时，Fe（Ⅲ）-空位机理变得更具能量竞争性。提出了计算的结合能和优化的键长。观察到质子运动满足针铁矿结构中Fe（Ⅲ）-空位周围的配位不足的键。

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  • 来源
    《Environmental Science & Technology》 |2015年第22期|13699-13707|共9页
  • 作者

    Frances N. Smith; Christopher D. Taylor; Wooyong Um; Albert A. Kruger;

  • 作者单位

    Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States ,Pacific Northwest National Laboratory, P.O. Box 999, MS-IN P7-25, Richland, WA 99352;

    Fontana Corrosion Center, Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, United States ,Strategic Research and Innovation, DNV GL, Dublin, Ohio 43017, United States;

    Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States;

    United States Department of Energy, Office of River Protection, P.O. Box 450, 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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