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

Morrison, Keith D.; Jiao, Yongqin; Kersting, Annie B.; Zavarin, Mavrik

doi:10.1021/acs.est.8b00164

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

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Abstract

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 othermore »« less

Authors:

^[1];

^[1]; Kersting, Annie B. ^[1]; Zavarin, Mavrik ^[1]

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

Publication Date:: 2018-05-16

Research Org.:: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:: 1491652

Report Number(s):: LLNL-JRNL-744940
Journal ID: ISSN 0013-936X; 898635

Grant/Contract Number:: AC52-07NA27344

Resource Type:: Accepted Manuscript

Journal Name:: Environmental Science and Technology

Additional Journal Information:: Journal Volume: 52; Journal Issue: 11; Journal ID: ISSN 0013-936X

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats


                    Morrison, Keith D., Jiao, Yongqin, Kersting, Annie B., and Zavarin, Mavrik. Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH.  United States: N. p., 2018. 
Web.  doi:10.1021/acs.est.8b00164.

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                    Morrison, Keith D., Jiao, Yongqin, Kersting, Annie B., & Zavarin, Mavrik. Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH.  United States.  https://doi.org/10.1021/acs.est.8b00164

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                    Morrison, Keith D., Jiao, Yongqin, Kersting, Annie B., and Zavarin, Mavrik. Wed .  
"Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH".  United States.  https://doi.org/10.1021/acs.est.8b00164.  https://www.osti.gov/servlets/purl/1491652.

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@article{osti_1491652,

  title        = {Reduction of Plutonium(VI) to (V) by Hydroxamate Compounds at Environmentally Relevant pH},

  author       = {Morrison, Keith D. and Jiao, Yongqin and Kersting, Annie B. and Zavarin, Mavrik},

  abstractNote = {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.},

  doi          = {10.1021/acs.est.8b00164},

  journal      = {Environmental Science and Technology},

  number       = 11,

  volume       = 52,

  place        = {United States},

  year         = {2018},

  month        = {5}

}

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