Reduction of Np(VI) and Pu(VI) by Organic Chelating Agents

Reed, Donald T.; Aase, S. B.; Banaszak, James E.

doi:10.1524/ract.1998.82.special-issue.109

Cited by 40 publications

(35 citation statements)

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“…Concurrently, uranyl and plutonyl were also not reduced and remained stable in their higher-valent form throughout the ∼1-week duration of the experiments. In the longer term, based on the abiotic chemistry [20], a slow reduction of plutonyl is likely given the many organic species present and generated in this system but we did not observe this in the timeframe of our experiments.…”

Section: Bioreduction Of Higher-valent Uranyl and Plutonylmentioning

confidence: 72%

“…Plutonium (99% Pu-242 by mass), was oxidized to PuO 2 2+ by fuming in perchloric acid [1,20] and dissolved in 0.1 M hydrochloric acid. PuO 2 + was synthesized by adding Pu(VI) to 0.1 M PIPES at pH ∼ 7 and letting it sit overnight leading to essentially complete reduction to Pu(V).…”

Section: Experimental Approachmentioning

confidence: 99%

“…Higher-valent uranium and plutonium species can be stable towards reduction for relatively long periods of time in the absence of reducing agents and at near-neutral pH [1,20]. They also can persist for a fairly long time (weeks) as meta-stable species in the aqueous phase at apparent solubilities that are much higher than their true solubility.…”

Section: Abiotic Reduction Of U(vi) Pu(v) and Pu(vi)mentioning

confidence: 99%

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Subsurface bio-mediated reduction of higher-valent uranium and plutonium

Reed

Pepper

Richmann

et al. 2007

Journal of Alloys and Compounds

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Bio-mediated reduction of multivalent actinide contaminants plays an important role in their fate and transport in the subsurface. To initiate the process of extending recent progress in uranium biogeochemistry to plutonium, a side-by-side comparison of the bioreduction of uranyl and plutonyl species was conducted with Shewanella alga BrY, a facultative metal-reducing bacterium that is known to enzymatically reduce uranyl. Uranyl was reduced in our system, consistent with literature reports, but we have noted a strong coupling between abiotic and biotic processes and observe that non-reductive pathways to precipitation typically exist. Additionally, a key role of biogenic Fe 2+ , which is known to reduce uranyl at low pH, is suggested. In contrast, residual organics, present in biologically active systems, reduce Pu(VI) species to Pu(V) species at near-neutral pH. The predominance of relatively weak complexes of PuO 2 + is an important difference in how the uranyl and plutonyl species interacted with S. alga. Pu(V) also led to increased toxicity towards S. alga and is also more easily reduced by microbial activity. Biogenic Fe 2+ , produced by S. alga when Fe(III) is present as an electron acceptor, also played a key role in understanding redox controls and pathways in this system. Overall, the bioreduction of plutonyl is observed under anaerobic conditions, which favors its immobilization in the subsurface. Understanding the mechanism by which redox control is established in biologically active systems is a key aspect of remediation and immobilization strategies for actinides when they are present as subsurface contaminants.

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Section: Bioreduction Of Higher-valent Uranyl and Plutonylmentioning

confidence: 72%

Section: Experimental Approachmentioning

confidence: 99%

Section: Abiotic Reduction Of U(vi) Pu(v) and Pu(vi)mentioning

confidence: 99%

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Subsurface bio-mediated reduction of higher-valent uranium and plutonium

Reed

Pepper

Richmann

et al. 2007

Journal of Alloys and Compounds

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“…Additionally, recent evidence suggests that chelates function as "catalysts" for biotic and abiotic electron transfer reactions. REED et al 154 found that EDTA, citrate, and oxalate reduce An(VI) to An(V/IV) in WIPP brines. In biological systems, the presence of organic chelating agents accelerates the growth of organisms utilizing solid electron-acceptor substrates.…”

Section: Biodegradation Of Organic Compounds and Chelating Agentsmentioning

confidence: 99%

Subsurface interactions of actinide species and microorganisms: Implications for the bioremediation of actinide-organic mixtures

Banaszak

Rittmann

Reed

1999

J Radioanal Nucl Chem

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“…Peroxide reduction of Pu(VI) is well documented [5,6] and H 2 O 2 is the primary product of alpha radiolysis [7], but [Pu(VI)]-time data for 239 Pu(VI) [8] and 242 Pu(VI) [9] show that self-reduction is most rapid near zero time. At that point, concentrations of H 2 O 2 and other radiolytic reductants are low and reduction of Pu(VI) should be slow.…”

Section: Introductionmentioning

confidence: 99%