Boglaienko Daria, Soltis Jennifer A, Kukkadapu Ravi K, Du Yingge, Sweet Lucas E, Holfeltz Vanessa E, Hall Gabriel B, Buck Edgar C, Segre Carlo U, Emerson Hilary P, Katsenovich Yelena, Levitskaia Tatiana G
Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
Illinois Institute of Technology, Chicago, IL, 60616, USA.
Commun Chem. 2020 Jul 10;3(1):87. doi: 10.1038/s42004-020-0334-x.
The sequestration of metal ions into the crystal structure of minerals is common in nature. To date, the incorporation of technetium(IV) into iron minerals has been studied predominantly for systems under carefully controlled anaerobic conditions. Mechanisms of the transformation of iron phases leading to incorporation of technetium(IV) under aerobic conditions remain poorly understood. Here we investigate granular metallic iron for reductive sequestration of technetium(VII) at elevated concentrations under ambient conditions. We report the retarded transformation of ferrihydrite to magnetite in the presence of technetium. We observe that quantitative reduction of pertechnetate with a fraction of technetium(IV) structurally incorporated into non-stoichiometric magnetite benefits from concomitant zero valent iron oxidative transformation. An in-depth profile of iron oxide reveals clusters of the incorporated technetium(IV), which account for 32% of the total retained technetium estimated via X-ray absorption and X-ray photoelectron spectroscopies. This corresponds to 1.86 wt.% technetium in magnetite, providing the experimental evidence to theoretical postulations on thermodynamically stable technetium(IV) being incorporated into magnetite under spontaneous aerobic redox conditions.
金属离子螯合到矿物晶体结构中在自然界很常见。迄今为止，主要针对在精心控制的厌氧条件下的体系研究了将锝（IV）掺入铁矿物的情况。在有氧条件下导致锝（IV）掺入的铁相转变机制仍知之甚少。在此，我们研究了粒状金属铁在环境条件下对高浓度锝（VII）的还原螯合作用。我们报告了在锝存在下，水铁矿向磁铁矿的转变受到抑制。我们观察到，高锝酸盐的定量还原以及一部分锝（IV）在结构上掺入非化学计量的磁铁矿，得益于伴随的零价铁氧化转变。对氧化铁的深入剖析揭示了掺入的锝（IV）簇，通过X射线吸收和X射线光电子能谱估计，这些簇占保留的总锝的32%。这相当于磁铁矿中锝的含量为1.86 wt.%，为关于在自发有氧氧化还原条件下热力学稳定的锝（IV）掺入磁铁矿的理论假设提供了实验证据。
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