Uranium(V) Incorporation Mechanisms and Stability in Fe(II)/Fe(III) (oxyhydr)Oxides
Uranium(V) Incorporation Mechanisms and Stability in Fe(II)/Fe(III) (oxyhydr)Oxides
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DOI：
10.1021/acs.estlett.7b00348
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发表时间：
2017-10-01
影响因子：
10.9
通讯作者：
Shaw, Samuel
中科院分区：
文献类型：
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作者：
Roberts, Hannah E.;Morris, Katherine;Shaw, Samuel
了解放射性核素和矿物相之间的相互作用是核工业现场环境清理和废物管理的基础。放射性核素在许多地下环境中的迁移和归宿受吸附、氧化还原和矿物掺入过程的控制。由于铀作为一种环境污染物的丰富性以及氧化铁在工程和自然环境中的普遍性，氧化铁与铀的相互作用已被广泛研究。尽管如此，详细的机械信息纳入铀铁（II）轴承磁铁矿和绿色锈是稀疏的。在这里，我们提出了一个共沉淀研究中，U（VI）与环境相关的铁（II/III）（oxyhydr）氧化物矿物相反应。的基础上的衍射，显微镜，溶解，和光谱证据，我们表明减少U（VI）的U（V）和稳定的U（V）的结合在近表面和大部分的颗粒在共沉淀过程中与铁（oxyhydr）氧化物。U（V）在磁铁矿和绿色锈结构中都是稳定的，并通过在类铀酸盐配位环境中取代八面体配位的Fe而结合。随着Fe（II）/Fe（III）比率的增加，一定比例的U（IV）也以表面缔合的UO 2形式沉淀。这些新的观察结果对铀在工程和自然环境中的行为具有重要意义。
Understanding interactions between radionuclides and mineral phases underpins site environmental cleanup and waste management in the nuclear industry. The transport and fate of radionuclides in many subsurface environments are controlled by adsorption, redox, and mineral incorporation processes. Interactions of iron (oxyhydr)oxides with uranium have been extensively studied because of the abundance of uranium as an environmental contaminant and the ubiquity of iron (oxyhydr)oxides in engineered and natural environments. Despite this, detailed mechanistic information regarding the incorporation of uranium into Fe(II)-bearing magnetite and green rust is sparse. Here, we present a co-precipitation study in which U(VI) was reacted with environmentally relevant iron(II/III) (oxyhydr)oxide mineral phases. On the basis of diffraction, microscopic, dissolution, and spectroscopic evidence, we show the reduction of U(VI) to U(V) and stabilization of the U(V) by incorporation within the near surface and bulk of the particles during co-precipitation with iron (oxyhydr)oxides. U(V) was stable in both magnetite and green rust structures and incorporated via substitution for octahedrally coordinated Fe in a uranate-like coordination environment. As the Fe(II)/Fe(III) ratio increased, a proportion of U(IV) was also precipitated as surface associated UO2. These novel observations have significant implications for the behavior of uranium within engineered and natural environments.