Solubility of U(VI) in Highly Basic Solutions

T. Yamamura; A. Kitamura; A. Fukui; S. Nishikawa; T. Yamamoto; H. Moriyama

Solubility of U(VI) in Highly Basic Solutions

T. Yamamura, A. Kitamura, A. Fukui, S. Nishikawa, T. Yamamoto, H. Moriyama

International Research Center for Nuclear Materials Science

Research output: Contribution to journal › Article › peer-review

41 Citations (Scopus)

Abstract

The solubility of U(VI) was measured in highly basic solutions (p0Hc = -log[OH] ranges from 3 down to 0) at the ionic strength I = 0.5 - 2.0 M (M: mol dm ^-3) over a wide range of carbonate ion concentrations C = 1 × 10^-3 -0.5 M by both oversaturation and undersaturation methods. In oversaturation experiments, the solubility of U(VI) decreased with increasing equilibration time from 1 week to 1 year, suggesting an increase in the crystallinity of the solid phase with aging. The solid phase was identified as Na₂U₂O₇ · x H₂O (x = 3-5) by X-ray diffraction. Undersaturation experiments conducted for 1 month with this solid phase indicated a rapid attainment of equilibrium. These data were well interpreted by considering the formation of [UO₂(OH)₃]^-, [UO₂(OH),]^2- and [UO₂(CO₃)₃]^4-, and the apparent equilibrium constants for [UO (OH)₃]^- and [UC₂(OH)₄,]^2- were determined with fairly small deviations. Using the evaluated solubility product of Na₂U₂O₇ · x H₂O (x = 3-5), the stability constants for the above species were evaluated. The upper limit values of the stability constants of the carbonatohydroxodioxouranium(VI) complexes were also evaluated.

Original language	English
Pages (from-to)	139-146
Number of pages	8
Journal	Radiochimica Acta
Volume	83
Issue number	3
Publication status	Published - 1998

Keywords

Carbonate
Equilibrium constant
Hydrolysis
Solubility
Solubility limiting solid phase
U(VI)

ASJC Scopus subject areas

Physical and Theoretical Chemistry

Cite this

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title = "Solubility of U(VI) in Highly Basic Solutions",

abstract = "The solubility of U(VI) was measured in highly basic solutions (p0Hc = -log[OH] ranges from 3 down to 0) at the ionic strength I = 0.5 - 2.0 M (M: mol dm -3) over a wide range of carbonate ion concentrations C = 1 × 10-3 -0.5 M by both oversaturation and undersaturation methods. In oversaturation experiments, the solubility of U(VI) decreased with increasing equilibration time from 1 week to 1 year, suggesting an increase in the crystallinity of the solid phase with aging. The solid phase was identified as Na2U2O7 · x H2O (x = 3-5) by X-ray diffraction. Undersaturation experiments conducted for 1 month with this solid phase indicated a rapid attainment of equilibrium. These data were well interpreted by considering the formation of [UO2(OH)3]-, [UO2(OH),]2- and [UO2(CO3)3]4-, and the apparent equilibrium constants for [UO (OH)3]- and [UC2(OH)4,]2- were determined with fairly small deviations. Using the evaluated solubility product of Na2U2O7 · x H2O (x = 3-5), the stability constants for the above species were evaluated. The upper limit values of the stability constants of the carbonatohydroxodioxouranium(VI) complexes were also evaluated.",

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author = "T. Yamamura and A. Kitamura and A. Fukui and S. Nishikawa and T. Yamamoto and H. Moriyama",

year = "1998",

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journal = "Radiochimica Acta",

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T1 - Solubility of U(VI) in Highly Basic Solutions

AU - Yamamura, T.

AU - Kitamura, A.

AU - Fukui, A.

AU - Nishikawa, S.

AU - Yamamoto, T.

AU - Moriyama, H.

PY - 1998

Y1 - 1998

N2 - The solubility of U(VI) was measured in highly basic solutions (p0Hc = -log[OH] ranges from 3 down to 0) at the ionic strength I = 0.5 - 2.0 M (M: mol dm -3) over a wide range of carbonate ion concentrations C = 1 × 10-3 -0.5 M by both oversaturation and undersaturation methods. In oversaturation experiments, the solubility of U(VI) decreased with increasing equilibration time from 1 week to 1 year, suggesting an increase in the crystallinity of the solid phase with aging. The solid phase was identified as Na2U2O7 · x H2O (x = 3-5) by X-ray diffraction. Undersaturation experiments conducted for 1 month with this solid phase indicated a rapid attainment of equilibrium. These data were well interpreted by considering the formation of [UO2(OH)3]-, [UO2(OH),]2- and [UO2(CO3)3]4-, and the apparent equilibrium constants for [UO (OH)3]- and [UC2(OH)4,]2- were determined with fairly small deviations. Using the evaluated solubility product of Na2U2O7 · x H2O (x = 3-5), the stability constants for the above species were evaluated. The upper limit values of the stability constants of the carbonatohydroxodioxouranium(VI) complexes were also evaluated.

AB - The solubility of U(VI) was measured in highly basic solutions (p0Hc = -log[OH] ranges from 3 down to 0) at the ionic strength I = 0.5 - 2.0 M (M: mol dm -3) over a wide range of carbonate ion concentrations C = 1 × 10-3 -0.5 M by both oversaturation and undersaturation methods. In oversaturation experiments, the solubility of U(VI) decreased with increasing equilibration time from 1 week to 1 year, suggesting an increase in the crystallinity of the solid phase with aging. The solid phase was identified as Na2U2O7 · x H2O (x = 3-5) by X-ray diffraction. Undersaturation experiments conducted for 1 month with this solid phase indicated a rapid attainment of equilibrium. These data were well interpreted by considering the formation of [UO2(OH)3]-, [UO2(OH),]2- and [UO2(CO3)3]4-, and the apparent equilibrium constants for [UO (OH)3]- and [UC2(OH)4,]2- were determined with fairly small deviations. Using the evaluated solubility product of Na2U2O7 · x H2O (x = 3-5), the stability constants for the above species were evaluated. The upper limit values of the stability constants of the carbonatohydroxodioxouranium(VI) complexes were also evaluated.

KW - Carbonate

KW - Equilibrium constant

KW - Hydrolysis

KW - Solubility

KW - Solubility limiting solid phase

KW - U(VI)

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SN - 0033-8230

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ER -

Solubility of U(VI) in Highly Basic Solutions

Abstract

Keywords

ASJC Scopus subject areas

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