Solubility of U(YI) in Highly Basic Solutions

Yamamura, Tomoo; Kitamura, Akira; Fukui, A.; Nishikawa, Sataro; Yamamoto, Takao A.; Moriyama, Hirotake

doi:10.1524/ract.1998.83.3.139

Cited by 54 publications

(35 citation statements)

References 16 publications

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“…The latter phase was synthesized under hydrothermal conditions, whereas the former phase can precipitate from ambient solutions at neutral and high pH and with high and low concentrations of Na [53,54]. Giammar and Hering [53] showed that metaschoepite transforms into a clarkeite-type phase in the presence of Na ions in solution.…”

Section: Na-uranyl-hydroxy-hydrate Precipitatesmentioning

confidence: 99%

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Schindler¹,

Hawthorne

Mandaliev

et al. 2011

Radiochimica Acta

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Summary.Understanding the mechanism(s) of uraniummineral dissolution is crucial for predictive modeling of U mobility in the subsurface. In order to understand how pH and type of cation in solution may affect dissolution, experiments were performed on mainly single crystals of curite, PbSolutions included: deionized water; aqueous HCl solutions at pH 3.5 and 2; 0.5 mol L −1 Pb(II)-, Ba-, Sr-, Ca-, Mg-, HCl solutions at pH 2; 1.0 mol L −1 Na-and K-HCl solutions at pH 2; and a 0.1 mol L −1 Na 2 CO 3 solution at pH 10.5. Uranyl mineral basal surface microtopography, micromorphology, and composition were examined prior to, and after dissolution experiments on micrometer scale specimens using atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Evolution of etch pit depth at different pH values and experimental durations can be explained using a stepwave dissolution model. Effects of the cation in solution on etch pit symmetry and morphology can be explained using an adsorption model involving specific surface sites. Surface precipitation of the following phases was observed: (a) a highly-hydrated uranyl-hydroxy-hydrate in ultrapure water (on all minerals), (b) a Na-uranyl-hydroxy-hydrate in Na 2 CO 3 solution of pH 10.5 (on uranyl-hydroxy-hydrate minerals), (c) a Na-uranyl-carbonate on zippeite, (d) Ba-and Pb-uranylhydroxy-hydrates in Ba-HCl and Pb-HCl solutions of pH 2 (on uranophane), (e) a (SiO x (OH) 4−2x ) phase in solutions of pH 2 (uranophane), and (f) sulfate-bearing phases in solutions of pH 2 and 3.5 (on zippeite).

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Section: Na-uranyl-hydroxy-hydrate Precipitatesmentioning

confidence: 99%

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Schindler¹,

Hawthorne

Mandaliev

et al. 2011

Radiochimica Acta

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“…Also, it is reported that 0.1M CO 3 2-resulted in Na 2 U 2 O 7 dissolution in highly basic solutions (Yamamura et al, 1998). In the present study, 0.28 mM UO 2 (NO 3 ) 2 solution was added into different concentrations of CO 3 2-(0.05~1.50M as Na 2 CO 3 ) in 1M NaOH solution to study the effect of CO 3 2-on uranium dissolution.…”

Section: Effect Of Co 3 2-on Uranium Dissolution/precipitationmentioning

confidence: 85%

Immobilization of Radionuclides in The Hanford Vadose Zone by Incorporation in Solid Phases

Mullins¹,

Traina²

2004

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“…Other possible reasons for the high Na 2 U 2 O 7 (am) SI values include the possibility that the K sp value of Yamamura et al (1998) used for this solid is not correct for the phase in our experiments and the possible formation of colloidal size uranium-bearing particles that could pass through the 0.45 μm filters used to filter the solutions prior to analysis. Other workers measuring the solubility of UO 2 2+ precipitates have used filters with much smaller pore sizes to avoid this problem (e.g., Rai et al 2002;Yamamura et al 1998).…”

Section: Uranium Mineral Solubility Measurementsmentioning

confidence: 98%

“…Two different NaOH concentrations in the range used by Yamamura et al (1998) were selected. Na 2 CO 3 was only added on the fourth replenishment of the third solution, in case carbonate contamination becomes unavoidable.…”

Section: I Extraction and Analysismentioning

confidence: 99%

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Hanford Tanks 241-C-202 and 241-C-203 Residual Waste Contaminant Release Models and Supporting Data

Deutsch¹,

Krupka²,

Lindberg³

et al. 2007

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SummaryAs directed by Congress, the U.S. Department of Energy (DOE) established the Office of River Protection in 1998 to manage DOE's largest, most complex environmental cleanup project -retrieval of radioactive waste from Hanford tanks for treatment and eventual disposal. Sixty percent by volume of the nation's high-level radioactive waste is stored at Hanford in aging deteriorating tanks. If not cleaned up, this waste is a threat to the Columbia River and the Pacific Northwest.CH2M HILL Hanford Group, Inc. is the Office of River Protection's prime contractor responsible for the storage, retrieval, and disposal of Hanford's tank waste. As part of this effort, CH2M HILL Hanford Group, Inc. contracted with Pacific Northwest National Laboratory (PNNL) to develop release models for key contaminants that are present in residual sludge remaining in Hanford Tanks 241-C-202 (C-202) and 241-C-203 (C-203). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. These release models are being developed to support the tank risk assessments performed by CH2M HILL Hanford Group, Inc. for DOE.The contaminant release models developed for these tanks are based on empirical solubility release models. Sludge testing was not successful in identifying minerals in the solids that may be limiting contaminant release; thus, it was not possible to develop mechanistic release models for the residual sludge in these tanks. The empirical release models apply to two different tank scenarios. In the first scenario the tank is filled with a relatively inert material, such as sand, and the leaching solution that contacts sludge in the future is in equilibrium with calcite (CaCO 3 ). Equilibrium with calcite is the typical condition for Hanford vadose zone porewater and groundwater, and Ca 2+ and CO 3 2-/HCO 3 -are the common major cation and anions in solution. Alternatively, the tanks might be filled with a cementitious material, which would produce a Ca(OH) 2 dominated leaching solution while the cement is fresh. As the cement reacts with infiltrating water and ages, it would evolve to resemble the CaCO 3 solution of the first scenario. Empirical solubility release models for the primary contaminants of interest (U, Cr, and 99 Tc) have been developed from laboratory leaching tests of sludge samples using the Ca(OH) 2 and CaCO 3 leaching solutions. Results for 129 I results were below the detection limit.Key results from this work are that future release concentrations from these tanks of the primary contaminants of concern in most cases represent less than 10% of the total contaminant concentration in the sludge. That is, the contaminants are not appreciably soluble in the Ca(OH) 2 and CaCO 3 leaching solutions. For example, the cumulative amount of U leached by the Ca(OH) 2 leaching solution during six sequential stages of leaching represented only 0.13% and 0.11% of the total uranium in tanks C-202 and C-203, respectively. The corresponding percentages of U leached...

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Solubility of U(YI) in Highly Basic Solutions

Cited by 54 publications

References 16 publications

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Immobilization of Radionuclides in The Hanford Vadose Zone by Incorporation in Solid Phases

Hanford Tanks 241-C-202 and 241-C-203 Residual Waste Contaminant Release Models and Supporting Data

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