Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH

Journal Article · Wed May 16 00:00:00 EDT 2018 · Environmental Science and Technology

DOI:https://doi.org/10.1021/acs.est.8b00164· OSTI ID:1491652

Morrison, Keith D. ^[1]; Jiao, Yongqin ^[1]; Kersting, Annie B. ^[1]; Zavarin, Mavrik ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Natural organic matter is known to influence the mobility of plutonium (Pu) in the environment via complexation and reduction mechanisms. Hydroxamate siderophores have been specifically implicated due to their strong association with Pu. Hydroxamate siderophores can also break down into di and mono-hydroxamates and may influence Pu oxidation state, and thereby its mobility. In this study we explored the reactions of Pu(VI) and Pu(V) with a mono-hydroxamate compound (acetohydroxamic acid, AHA) and a tri-hydroxamate siderophore desferrioxamine B (DFOB) at environmentally relevant pH (5.5-8.2). Pu(VI) was instantaneously reduced to Pu(V) upon reaction with AHA. The presence of hydroxylamine was not observed at these pHs; however, AHA was consumed during the reaction. This suggests that the reduction of Pu(VI) to Pu(V) by AHA is facilitated by direct one electron transfer. Importantly, further reduction to Pu(IV) or Pu(III) was not observed, even with excess AHA. We believe that further reduction of Pu(V) did not occur because Pu(V) does not form a strong complex with hydroxamate compounds at circum-neutral pH. Experiments performed using desferrioxamine B (DFOB) yielded similar results. Broadly, this suggests that Pu(V) reduction to Pu(IV) in the presence of natural organic matter is not facilitated by hydroxamate functional groups and that other natural organic matter moieties likely play a more prominent role.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1491652
• Report Number(s): LLNL-JRNL--744940; 898635
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 11 Vol. 52; ISSN 0013-936X
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY