TY - JOUR
T1 - Thermodynamic characterization of boltwoodite and uranophane
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
N1 - Funding Information:
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.
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.
UR - http://www.scopus.com/inward/record.url?scp=80051474169&partnerID=8YFLogxK
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U2 - 10.1016/j.gca.2011.06.041
DO - 10.1016/j.gca.2011.06.041
M3 - Article
AN - SCOPUS:80051474169
SN - 0016-7037
VL - 75
SP - 5269
EP - 5282
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
IS - 18
ER -