Formation of crystalline PuO2+·nH2O nanoparticles upon sorption of Pu(V,VI) onto hematite

Romanchuk, Anna Yu.; Kalmykov, Stepan N.; Егоров, А. В.; Zubavichus, Yan V.; Shiryaev, A. A.; Batuk, Olga N.; Conradson, Steven D.; Pankratov, D. А.; Presnyakov, I. A.

doi:10.1016/j.gca.2013.07.016

Cited by 47 publications

(48 citation statements)

References 49 publications

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“…High-resolution transmission electron microscopy (HRTEM) imaging (see Fig. S6 in the supplemental material) indicated that the nanocrystalline Pu(IV)O 2 precipitates have a crystallite dimension of 2 to 3 nm, similar to those previously observed under similar solution conditions (13,42,43). The main features of the corresponding electron diffraction patterns match the face-centered cubic (fcc) Pu(IV)O 2 crystal structure (see Fig.…”

Section: Cellular Pu Sorption and Reduction Pseudomonas Sp Eps-1wsupporting

confidence: 77%

Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Boggs

Jiao

Dai

et al. 2016

Appl Environ Microbiol

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Safe and effective nuclear waste disposal, as well as accidental radionuclide releases, necessitates our understanding of the fate of radionuclides in the environment, including their interaction with microorganisms. We examined the sorption of Pu(IV) and Pu(V) to Pseudomonas sp. strain EPS-1W, an aerobic bacterium isolated from plutonium (Pu)-contaminated groundwater collected in the United States at the Nevada National Security Site (NNSS) in Nevada. We compared Pu sorption to cells with and without bound extracellular polymeric substances (EPS). Wild-type cells with intact EPS sorbed Pu(V) more effectively than cells with EPS removed. In contrast, cells with and without EPS showed the same sorption affinity for Pu(IV). In vitro experiments with extracted EPS revealed rapid reduction of Pu(V) to Pu(IV). Transmission electron microscopy indicated that 2-to 3-nm nanocrystalline Pu(IV)O 2 formed on cells equilibrated with high concentrations of Pu(IV) but not Pu(V). Thus, EPS, while facilitating Pu(V) reduction, inhibit the formation of nanocrystalline Pu(IV) precipitates. IMPORTANCEOur results indicate that EPS are an effective reductant for Pu(V) and sorbent for Pu(IV) and may impact Pu redox cycling and mobility in the environment. Additionally, the resulting Pu morphology associated with EPS will depend on the concentration and initial Pu oxidation state. While our results are not directly applicable to the Pu transport situation at the NNSS, the results suggest that, in general, stationary microorganisms and biofilms will tend to limit the migration of Pu and provide an important Pu retardation mechanism in the environment. In a broader sense, our results, along with a growing body of literature, highlight the important role of microorganisms as producers of redox-active organic ligands and therefore as modulators of radionuclide redox transformations and complexation in the subsurface.T he civil production of nuclear energy and military production of nuclear materials have resulted in an estimated worldwide inventory of over 2,000 metric tons of plutonium (Pu) (1). This inventory continues to increase at a rate of approximately 70 metric tons per year as a result of global nuclear energy production (2). Due to its long half-life (24,100 years for 239 Pu) and high radiotoxicity (3), Pu is an important driver in public health risk assessments for nuclear waste repositories and radiologically contaminated sites. However, predicting how Pu behaves in the environment and ultimately calculating its human health risk are limited by our understanding of the dominant biogeochemical processes controlling its behavior.The behavior of Pu in the environment is strongly dependent on its oxidation state and concentration. Among all the actinides, Pu has one of the most complex chemical, redox, and surface sorption behaviors. At low concentrations, Pu can exist as aqueous species in the III, IV, V, and/or VI oxidation states, all of which have different solubilities (4), mineral sorption affinities (5-7), and hence...

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Section: Cellular Pu Sorption and Reduction Pseudomonas Sp Eps-1wsupporting

confidence: 77%

Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Boggs

Jiao

Dai

et al. 2016

Appl Environ Microbiol

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“…In addition, different shapes and appearances of the polymers either aggregated or grown on mineral surfaces were observed (Thiyagarajan et al, 1990;Powell et al, 2011;Zavarin et al, 2012). Recently, researchers indicated that Pu intrinsic colloid was characterized by crystalline structures (Soderholm et al, 2008;Powell et al, 2011;Delegard, 2013;Romanchuk et al, 2013). They called them crystalline nanoparticles rather than polymers, although the term "polymer" was widely used in many reports (Kersting, 2013;Walther and Denecke, 2013;Marsac et al, 2014).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Trace-level plutonium(IV) polymer stability and its transport in coarse-grained granites

et al. 2015

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“…Several studies have shown that minerals may facilitate surface-mediated reduction of Pu(V/VI) to Pu(IV/III) even on minerals that are considered oxidizing or non-reactive [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Theories proposed to describe the surface-mediated reduction of Pu are shown below [14], however disproportionation and self-reduction have been previously proven negligible at environmentally relevant pH values and concentrations of Pu [17,19]: -Thermodynamic favorability of Pu(IV) hydroxide complexes [14,18,19,24].…”

Section: Introductionmentioning

confidence: 99%

“…Theories proposed to describe the surface-mediated reduction of Pu are shown below [14], however disproportionation and self-reduction have been previously proven negligible at environmentally relevant pH values and concentrations of Pu [17,19]: -Thermodynamic favorability of Pu(IV) hydroxide complexes [14,18,19,24]. -Self-reduction via radiolysis byproducts [5,11,19].…”

Section: Introductionmentioning

confidence: 99%

“…It is a ferric oxide mineral and the absence of ferrous iron (Fe(II)) in the structure implies hematite will have little to no reduction capacity. However the presence of trace Fe(II) has been proposed to be responsible for the reduction of Pu(V/VI) on hematite [14,17,18,24]. Thus, Fe(II) is likely present in hematite but may be below analytical detection limits.…”

Section: Introductionmentioning

confidence: 99%

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Observations of surface-mediated reduction of Pu(VI) to Pu(IV) on hematite nanoparticles by ATR FT-IR

Emerson

Powell

2015

Radiochimica Acta

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Previous studies have shown that mineral surfaces may facilitate the reduction of plutonium though the mechanisms of the reduction are still unknown. The objective of this study is to use batch sorption and attenuated total reflectance Fourier transform infrared spectroscopy experiments to observe the surface-mediated reduction of plutonium on hematite nanoparticles. These techniques allow for in situ measurement of reduction of plutonium with time and may lead to a better understanding of the mechanisms of surface mediated reduction of plutonium. For the first time, ATR FT-IR peaks for Pu(VI) sorbed to hematite are measured at ∼ 916 cm −1 , respectively. The decrease in peak intensity with time provides a real-time, direct measurement of Pu(VI) reduction on the hematite surface. In this work pseudo first order rate constants estimated at the high loadings (22 mg Pu /g hematite , 1.34 × 10 −6 M Pu /m 2 ) for ATR FT-IR are approximately 10× slower than at trace concentrations based on previous work. It is proposed that the reduced rate constant at higher Pu loadings occurs after the reduction capacity due to trace Fe(II) has been exhausted and is dependent on the oxidation of water and possibly electron shuttling based on the semiconducting nature of hematite. Therefore, the reduction rate at higher loadings is possibly due to the thermodynamic favorability of Pu(IV)-hydroxide complexes.

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Formation of crystalline PuO2+·nH2O nanoparticles upon sorption of Pu(V,VI) onto hematite

Cited by 47 publications

References 49 publications

Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Trace-level plutonium(IV) polymer stability and its transport in coarse-grained granites

Observations of surface-mediated reduction of Pu(VI) to Pu(IV) on hematite nanoparticles by ATR FT-IR

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