Biogenic nanoparticulate UO2: Synthesis, characterization, and factors affecting surface reactivity

Singer, David M.; Farges, François; Brown, Gordon E.

doi:10.1016/j.gca.2009.03.031

Cited by 62 publications

(80 citation statements)

References 81 publications

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“…The precipitate is generally formed in the periplasm or externally to the cell, and may be associated with or near reductase cytochromes and exopolymeric substances (Marshall et al, 2006). Biogenic uraninite is nanoparticulate (2-10 nm), exhibiting a contraction of the U lattice compared with synthetic bulk UO 2 because of the large number of U atoms on the surface of the nanoparticle (approximately 50% of U atoms), whereas the core of the particle remains highly ordered stoichiometric UO 2 Schofield et al, 2008;Singer et al, 2009). The surface of the particle is slightly more disordered than the interior, but it is still essentially crystalline and stoichiometric, based on detailed X-ray absorption and synchrotron powder diffraction studies Bargar et al, 2009).…”

Section: Geomicrobiology Of U Oxidation and Reduction: Enzymatically mentioning

confidence: 99%

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Campbell¹,

Gallegos²,

Landa

2015

Applied Geochemistry

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aspects of uranium mineralization, mining, milling, and remediation" (2014 U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling of U-bearing ores is the first step in the nuclear fuel cycle, and the contact of residual waste with natural water is a potential source of contamination of U and associated elements to the environment. Uranium is mined by three basic methods: surface (open pit), underground, and solution mining (in situ leaching or in situ recovery), depending on the deposit grade, size, location, geology and economic considerations (Abdelouas, 2006). Solid wastes at U mill tailings (UMT) sites can include both standard tailings (i.e., leached ore rock residues) and solids generated on site by waste treatment processes. The latter can include sludge or ''mud'' from neutralization of acidic mine/mill effluents, containing Fe and a range of coprecipitated constituents, or barium sulfate precipitates that selectively remove Ra (e.g., Carvalho et al., 2007). In this chapter, we review the hydrometallurgical processes by which U is extracted from ore, the biogeochemical processes that can affect the fate and transport of U and associated elements in the environment, and possible remediation strategies for site closure and aquifer restoration. This paper represents the fourth in a series of review papers from the U.S. Geological Survey (USGS) on geochemical aspects of UMT management that span more than three decades. The first paper (Landa, 1980) in this series is a primer on the nature of tailings and radionuclide mobilization from them. The second paper (Landa, 1999) includes coverage of research carried out under the U.S. Department of Energy's Uranium Mill Tailings Remedial Action Program (UMTRA). The third paper (Landa, 2004) reflects the increased focus of researchers on biotic effects in UMT environs. This paper expands the focus to U mining, milling, and remedial actions, and includes extensive coverage of the increasingly important alkaline in situ recovery and groundwater restoration.Ó 2014 Published by Elsevier Ltd.

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Section: Geomicrobiology Of U Oxidation and Reduction: Enzymatically mentioning

confidence: 99%

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Campbell¹,

Gallegos²,

Landa

2015

Applied Geochemistry

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“…Full occupation of the uraninite surface sites by Ca 2+ would produce overall Ca:U ratios (i.e., in the bulk sample) approaching this value. The overall Ca:U ratios observed in this study via digestions (Ca:U was 0.21 to 0.31, cf., SI 39 then a surface Ca:bulk U ratio of 0.07 would be obtained. The upper limit on the sorption density of surface-complexed Ca (Γ Ca,max ) can be estimated by equating it to the density of proton-active surface sites, which is expected to be ca.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

Long-Term in Situ Oxidation of Biogenic Uraninite in an Alluvial Aquifer: Impact of Dissolved Oxygen and Calcium

Lezama‐Pacheco

Cerrato

Veeramani

et al. 2015

Environ. Sci. Technol.

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Oxidative dissolution controls uranium release to (sub)oxic pore waters from biogenic uraninite produced by natural or engineered processes, such as bioremediation. Laboratory studies show that uraninite dissolution is profoundly influenced by dissolved oxygen (DO), carbonate, and solutes such as Ca 2+. In complex and heterogeneous subsurface environments, the concentrations of these solutes vary in time and space. Knowledge of dissolution processes and kinetics occurring over the long-term under such conditions is needed to predict subsurface uranium behavior and optimize the selection and performance of uraninite-based remediation technologies over multiyear periods. We have assessed dissolution of biogenic uraninite deployed in wells at the Rifle, CO, DOE research site over a 22 month period. Uraninite loss rates were highly sensitive to DO, with near-complete loss at >0.6 mg/L over this period but no measurable loss at lower DO. We conclude that uraninite can be stable over decadal time scales in aquifers under low DO conditions. U(VI) solid products were absent over a wide range of DO values, suggesting that dissolution proceeded through complexation and removal of oxidized surface uranium atoms by carbonate. Moreover, under the groundwater conditions present, Ca 2+ binds strongly to uraninite surfaces at structural uranium sites, impacting uranium fate.

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“…Scanning electron microscopy (SEM) analysis revealed that nanoparticles exhibit extracellular accumulation [62]. The synthesis of biogenic UO2 nanoparticles (5-10 nm) was mediated by S. putrefaciens cell suspensions growing aerobically, followed by the anaerobic addition of a uranyl-bearing solution [(UO2 +2 )-PIPES,NH4Cl-lactate-KHCO3-K2HPO4] [63].…”

Section: Uraninite (Uo2) Nanoparticlesmentioning

confidence: 99%

“…These effects may be linked to the depleted uranium doses and independent of the solubility of uranium oxide [106]. The biotransformations of uranyl salts are an important way to avoid environment contamination, and the presence of protein capping on the surface of biogenically synthesized UO2 nanoparticles can avoid posterior metal solubilization [63]. Lee et al [111] reported the biogenic synthesis of UO2 (uraninite) nanocrystals by the iron-reducing bacterium, Shewanella putrefaciens CN32, from uranium-rich solution.…”

Section: Uraninite (Uo2) Nanoparticlesmentioning

confidence: 99%

Nanotoxicology of Metal Oxide Nanoparticles

Seabra

Durán

2015

Metals

191

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This review discusses recent advances in the synthesis, characterization and toxicity of metal oxide nanoparticles obtained mainly through biogenic (green) processes. The in vitro and in vivo toxicities of these oxides are discussed including a consideration of the factors important for safe use of these nanomaterials. The toxicities of different metal oxide nanoparticles are compared. The importance of biogenic synthesized metal oxide nanoparticles has been increasing in recent years; however, more studies aimed at better characterizing the potent toxicity of these nanoparticles are still necessary for nanosafely considerations and environmental perspectives. In this context, this review aims to inspire new research in the design of green approaches to obtain metal oxide nanoparticles for biomedical and technological applications and to highlight the critical need to fully investigate the nanotoxicity of these particles. OPEN ACCESSMetals 2015, 5 935

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Biogenic nanoparticulate UO2: Synthesis, characterization, and factors affecting surface reactivity

Cited by 62 publications

References 81 publications

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Long-Term in Situ Oxidation of Biogenic Uraninite in an Alluvial Aquifer: Impact of Dissolved Oxygen and Calcium

Nanotoxicology of Metal Oxide Nanoparticles

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