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.

中文翻译：

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Fe（II）/ Fe（III）（羟基）氧化物中铀（V）的掺入机理和稳定性

了解放射性核素和矿物质相之间的相互作用是核工业现场环境净化和废物管理的基础。放射性核素在许多地下环境中的传输和命运受吸附，氧化还原和矿物掺入过程控制。由于丰富的铀作为环境污染物，并且在工程和自然环境中普遍存在氧化铁（羟基氧化物），因此广泛研究了氧化铁（羟基氧化物）与铀的相互作用。尽管如此，有关将铀掺入含Fe（II）的磁铁矿和生铁锈的详细机械信息仍然很少。在这里，我们提出了一项共沉淀研究，其中U（VI）与环境相关的铁（II / III）（羟基）氧化物矿物相反应。根据衍射，微观，溶解和光谱学证据表明，在与铁（羟基氧化物）共沉淀过程中，通过掺入颗粒的近表面和主体内，U（VI）还原为U（V）并稳定了U（V）。U（V）在磁铁矿和生铁锈结构中都是稳定的，并且在类似尿酸盐的配位环境中通过取代八面体配位的Fe掺入。随着Fe（II）/ Fe（III）比的增加，一部分U（IV）也作为表面缔合的UO析出。U（V）在磁铁矿和生铁锈结构中都是稳定的，并且在类似尿酸盐的配位环境中通过取代八面体配位的Fe来掺入。随着Fe（II）/ Fe（III）比的增加，一部分U（IV）也作为表面缔合的UO析出。U（V）在磁铁矿和生铁锈结构中都是稳定的，并且在类似尿酸盐的配位环境中通过取代八面体配位的Fe来掺入。随着Fe（II）/ Fe（III）比的增加，一部分U（IV）也作为表面缔合的UO析出。₂。这些新颖的发现对工程环境和自然环境中铀的行为具有重要意义。