The role of pe, pH, and carbonate on the solubility of UO2 and uraninite under nominally reducing conditions

Casas, I.; Pablo, Joan de; Giménez, Javier; Torrero, M.E.; Bruno, Jordi; Cera, E.; Finch, Robert J.; Ewing, Rodney C.

doi:10.1016/s0016-7037(98)00140-9

Cited by 114 publications

(69 citation statements)

References 27 publications

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“…Enhanced reactivity of smaller UO 2 particles could simply be due to the greater exposed reactive surface area of smaller particles or the accumulation of insoluble U(VI) species on UO 2 grain boundaries that limit their further reaction with oxidants (Trocellier et al, 1995;Wronkiewicz et al, 1997;Casas et al, 1998). The role of U(IV)-associated phosphoryl groups (observed by EXAFS) in the oxidation of biogenic U(IV) is unclear.…”

Section: Uo 2 Particle Size and Aggregationmentioning

confidence: 99%

“…The reason for incomplete oxidation of UO 2 by nitrite (with or without Fe as an electron shuttle) is less clear, but may be attributed to thermodynamic (Ginder-Vogel et al, 2006), or physical (e.g., accumulation of U(VI) coatings on UO 2 particle surfaces (Trocellier et al, 1995;Wronkiewicz et al, 1997;Casas et al, 1998)) limitations on the reaction that arise as it proceeds. The susceptibility of biogenic UO 2 to oxidation by nitrite (without Fe as an electron shuttle) is surprising, since nitrite alone has been previously reported to be a relatively ineffective oxidant of U(IV) (Senko et al, 2005b).…”

Section: Uo 2 Oxidationmentioning

confidence: 99%

See 1 more Smart Citation

The effect of U(VI) bioreduction kinetics on subsequent reoxidation of biogenic U(IV)

Senko

Kelly

Dohnálková

et al. 2007

Geochimica et Cosmochimica Acta

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Section: Uo 2 Particle Size and Aggregationmentioning

confidence: 99%

Section: Uo 2 Oxidationmentioning

confidence: 99%

The effect of U(VI) bioreduction kinetics on subsequent reoxidation of biogenic U(IV)

Senko

Kelly

Dohnálková

et al. 2007

Geochimica et Cosmochimica Acta

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“…Therefore, research related to remediation of uranium-contaminated groundwater takes advantage of sulfate-, iron-, and manganesereducing bacteria to reduce uranium concentrations to low levels by reductive processes (e.g., Abdelouas et al, 2000;Yi et al, 2007). Experimental work suggests that crystallinity, particle size, chemical impurity, and mixed oxidation states all factor into uranium concentrations derived from uraninite dissolution (Finch and Ewing, 1992;Langmuir, 1997;Casas et al, 1998). Fig.…”

Section: Mineralogy Geochemistry and Genesis Of Roll-front Uranium mentioning

confidence: 99%

Potential aquifer vulnerability in regions down-gradient from uranium in situ recovery (ISR) sites

Saunders

Pivetz

Voorhies

et al. 2016

Journal of Environmental Management

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“…An increase in the release was quantified as a function of increasing bicarbonate concentration. Bicarbonate-promoted dissolution has been observed with numerous uranium minerals including uranophane (Casas et al 1997b;Perez et al 2000), soddyite (Perez et al 1997;Casas et al 1997b), uraninite (Casas et al 1998;Casas et al 1994;Pierce et al 2005;Grandstaff 1976;de Pablo et al 1999), becquerelite (Casas et al 1997a;Sowder et al 2000b;Hering and Schnoor 2000), and autunite-group minerals (Sowder et al 2000b). Casas et al (Perez et al 2000;Casas et al 1997b) quantified the solubility of uranophane through a series of static tests and provide a solubility constant of log K o so = 11.7 ± 0.6.…”

Section: Dissolution Kinetics Of Uranophanementioning

confidence: 99%

DNA Profile Analysis and Interpretation

2014

DNA Analysis for Missing Person Identification in Mass Fatalities

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SummaryThe Hanford Site is a former nuclear defense production facility. A groundwater plume containing uranium, originating from a combination of purposeful discharges of wastewater to cribs, trenches, and ponds, along with some accidental leaks and spills related to nuclear fuel fabrication activities, has persisted beneath the Hanford Site 300 Area for many years. Despite the cessation of uranium releases and the removal of shallow vadose zone source materials, the remedial action objective to lower the concentration of groundwater uranium to the U. S. Environmental Protection Agency maximum contaminant level concentration of 30 µg/L has not been achieved within the anticipated 10-year time period. Some unknown amount of contamination remains in the vadose zone beneath the lower extent of the excavation activities. Additional contamination also may remain beneath buildings and facilities in the southern portion of the 300 Area, which has not been decontaminated and decommissioned. The use of polyphosphate technology for source treatment in the vadose zone and capillary fringe is expected to accelerate the natural attenuation of uranium to thermodynamically stable uranium-phosphate minerals. This effort will complement the current 300 Area treatability test being conducted within the saturated zone (e.g., 300 Area aquifer) for in situ treatment of uranium-contaminated groundwater.Polyphosphate technology has been demonstrated for in situ precipitation of phosphate phases to control the long-term fate of uranium. A critical component of the development and testing is detailed evaluation to determine if polyphosphate technology could be modified for infiltration from ground surface or some depth of excavation to stabilize source uranium phases. This report presents results from bench-scale treatability studies conducted under site-specific conditions to optimize the polyphosphate amendment for implementation of a field-scale technology demonstration to stabilize uranium within the 300 Area vadose zone and capillary fringe of the Hanford Site. Documented in this report are data related to 1) the retardation of polyphosphate as a function of water content and pore water velocity, 2) the reaction between uranium-bearing solid phases and aqueous polyphosphate remediation technology as a function of polyphosphate composition and concentration, 3) the mechanism of autunite formation via the reaction of solid-phase calcite-bound uranium and aqueous polyphosphate remediation technology, 4) the transformation mechanism and reaction kinetics between uranyl-carbonate and -silicate minerals with the polyphosphate remedy under advective conditions, and 5) the extent and rate of uranium released and immobilized as a function of polyphosphate composition and the infiltration rate of the polyphosphate remedy. Kinetic rate law parameters were determined from single-pass flow-through experiments. Pressurized unsaturated flow tests were used to determine the effect of polyphosphate composition, concentration, and infiltration rate...

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The role of pe, pH, and carbonate on the solubility of UO2 and uraninite under nominally reducing conditions

Cited by 114 publications

References 27 publications

The effect of U(VI) bioreduction kinetics on subsequent reoxidation of biogenic U(IV)

The effect of U(VI) bioreduction kinetics on subsequent reoxidation of biogenic U(IV)

Potential aquifer vulnerability in regions down-gradient from uranium in situ recovery (ISR) sites

DNA Profile Analysis and Interpretation

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