Thermodynamic characterization of boltwoodite and uranophane: Enthalpy of formation and aqueous solubility

Tatiana Y. Shvareva; Lena Mazeina; Drew Gorman-Lewis; Peter C. Burns; Jennifer E.S. Szymanowski; Jeremy B. Fein; Alexandra Navrotsky

doi:10.1016/j.gca.2011.06.041

Thermodynamic characterization of boltwoodite and uranophane: Enthalpy of formation and aqueous solubility

Tatiana Y. Shvareva
, Lena Mazeina
, Drew Gorman-Lewis
, Peter C. Burns
, Jennifer E.S. Szymanowski
, Jeremy B. Fein
, Alexandra Navrotsky

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

41 Scopus citations

Abstract

Boltwoodite and uranophane are uranyl silicates common in oxidized zones of uranium ore deposits. An understanding of processes that impact uranium transport in the environment, especially pertaining to the distribution of uranium between solid phases and aqueous solutions, ultimately requires determination of thermodynamic parameters for such crystalline materials. We measured formation enthalpies of synthetic boltwoodites, K(UO₂)(HSiO₄)·H₂O and Na(UO₂)(HSiO₄)·H₂O, and uranophane, Ca(UO₂)₂(HSiO₄)₂·5H₂O, by high temperature oxide melt solution calorimetry. We also studied the aqueous solubility of these phases from both saturated and undersaturated conditions at a variety of pH. The combined data permit the determination of standard enthalpies, entropies and Gibbs free energies of formation for each phase and analysis of its potential geological impact from a thermodynamic point of view.

Original language	English
Pages (from-to)	5269-5282
Number of pages	14
Journal	Geochimica et Cosmochimica Acta
Volume	75
Issue number	18
DOIs	https://doi.org/10.1016/j.gca.2011.06.041
State	Published - Sep 15 2011
Externally published	Yes

Funding

This material is based upon work supported as part of the Materials Science of Actinides, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001089. Funding for the beginning stages of this project (prior to EFRC) was provided by a U.S. Department of Energy, Office of Science and Technology and International (OST&I) grant under the Source Term Thrust program.

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title = "Thermodynamic characterization of boltwoodite and uranophane: Enthalpy of formation and aqueous solubility",

abstract = "Boltwoodite and uranophane are uranyl silicates common in oxidized zones of uranium ore deposits. An understanding of processes that impact uranium transport in the environment, especially pertaining to the distribution of uranium between solid phases and aqueous solutions, ultimately requires determination of thermodynamic parameters for such crystalline materials. We measured formation enthalpies of synthetic boltwoodites, K(UO2)(HSiO4)·H2O and Na(UO2)(HSiO4)·H2O, and uranophane, Ca(UO2)2(HSiO4)2·5H2O, by high temperature oxide melt solution calorimetry. We also studied the aqueous solubility of these phases from both saturated and undersaturated conditions at a variety of pH. The combined data permit the determination of standard enthalpies, entropies and Gibbs free energies of formation for each phase and analysis of its potential geological impact from a thermodynamic point of view.",

author = "Shvareva, \{Tatiana Y.\} and Lena Mazeina and Drew Gorman-Lewis and Burns, \{Peter C.\} and Szymanowski, \{Jennifer E.S.\} and Fein, \{Jeremy B.\} and Alexandra Navrotsky",

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T2 - Enthalpy of formation and aqueous solubility

AU - Shvareva, Tatiana Y.

AU - Mazeina, Lena

AU - Gorman-Lewis, Drew

AU - Burns, Peter C.

AU - Szymanowski, Jennifer E.S.

AU - Fein, Jeremy B.

AU - Navrotsky, Alexandra

PY - 2011/9/15

Y1 - 2011/9/15

N2 - Boltwoodite and uranophane are uranyl silicates common in oxidized zones of uranium ore deposits. An understanding of processes that impact uranium transport in the environment, especially pertaining to the distribution of uranium between solid phases and aqueous solutions, ultimately requires determination of thermodynamic parameters for such crystalline materials. We measured formation enthalpies of synthetic boltwoodites, K(UO2)(HSiO4)·H2O and Na(UO2)(HSiO4)·H2O, and uranophane, Ca(UO2)2(HSiO4)2·5H2O, by high temperature oxide melt solution calorimetry. We also studied the aqueous solubility of these phases from both saturated and undersaturated conditions at a variety of pH. The combined data permit the determination of standard enthalpies, entropies and Gibbs free energies of formation for each phase and analysis of its potential geological impact from a thermodynamic point of view.

AB - Boltwoodite and uranophane are uranyl silicates common in oxidized zones of uranium ore deposits. An understanding of processes that impact uranium transport in the environment, especially pertaining to the distribution of uranium between solid phases and aqueous solutions, ultimately requires determination of thermodynamic parameters for such crystalline materials. We measured formation enthalpies of synthetic boltwoodites, K(UO2)(HSiO4)·H2O and Na(UO2)(HSiO4)·H2O, and uranophane, Ca(UO2)2(HSiO4)2·5H2O, by high temperature oxide melt solution calorimetry. We also studied the aqueous solubility of these phases from both saturated and undersaturated conditions at a variety of pH. The combined data permit the determination of standard enthalpies, entropies and Gibbs free energies of formation for each phase and analysis of its potential geological impact from a thermodynamic point of view.

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JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

IS - 18

ER -

Thermodynamic characterization of boltwoodite and uranophane: Enthalpy of formation and aqueous solubility

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