Oxidation State and Local Structure of Plutonium Reacted with Magnetite, Mackinawite, and Chukanovite

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• 作者：Regina Kirsch ; David Fellhauer ; Marcus Altmaier ; Volker Neck ; Andre Rossberg ; Thomas Fangh盲nel ; Laurent Charlet ; Andreas C. Scheinost
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：September 1, 2011
• 年：2011
• 卷：45
• 期：17
• 页码：7267-7274
• 全文大小：960K
• 年卷期：v.45,no.17(September 1, 2011)
• ISSN：1520-5851

文摘

Due to their redox reactivity, surface sorption characteristics, and ubiquity as corrosion products or as minerals in natural sediments, iron(II)-bearing minerals control to a large extent the environmental fate of actinides. Pu-L_III-edge XANES and EXAFS spectra were used to investigate reaction products of aqueous ²⁴²Pu(III) and ²⁴²Pu(V) reacted with magnetite, mackinawite, and chukanovite under anoxic conditions. As Pu concentrations in the liquid phase were rapidly below detection limit, oxidation state and local structure of Pu were determined for Pu associated with the solid mineral phase. Pu(V) was reduced in the presence of all three minerals. A newly identified, highly specific Pu(III)-sorption complex formed with magnetite. Solid PuO₂ phases formed in the presence of mackinawite and chukanovite; in the case of chukanovite, up to one-third of plutonium was also present as Pu(III). This highlights the necessity to consider, under reducing anoxic conditions, Pu(III) species in addition to tetravalent PuO₂ for environmental risk assessment. Our results also demonstrate the necessity to support thermodynamic calculations with spectroscopic data.