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Estevenon P, Dumas T, Solari PL, Welcomme E, Szenknect S, Mesbah A, Kvashnina KO, Moisy P, Poinssot C, Dacheux N. Formation of plutonium(IV) silicate species in very alkaline reactive media. Dalton Trans 2021; 50:12528-12536. [PMID: 34545888 DOI: 10.1039/d1dt02248b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Studying the speciation of Pu(IV) in very alkaline and silicate ion rich reactive media allowed identification of the formation of plutonium(IV)-silicate colloidal suspensions which were stable for months. These colloids were stabilized in aqueous solution for pH > 13 and for concentrations around 10-2 mol L-1. Successive filtration processes allowed evaluation of their size, which was found to be smaller than 6 nm. Their structural characterization by XAS evidenced that their structure was similar to those identified for the other tetravalent actinide-silicate colloidal systems like thorium, uranium and neptunium. Their formation could explain the increase of plutonium solubility usually observed in alkaline silicate-rich solutions and could affect the plutonium mobility as a result in contaminated sites or in other environmental permeable media.
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Affiliation(s)
- Paul Estevenon
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France. .,ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Bagnols-sur-Cèze, France. .,The Rossendorf Beamline at the ESRF, CS40220, 38043 Grenoble Cedex 9, France.,Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, P.O. Box 510119, 01314, Dresden, Germany
| | - Thomas Dumas
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France.
| | - Pier Lorenzo Solari
- Synchrotron Soleil, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | | | | | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Bagnols-sur-Cèze, France.
| | - Kristina O Kvashnina
- The Rossendorf Beamline at the ESRF, CS40220, 38043 Grenoble Cedex 9, France.,Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, P.O. Box 510119, 01314, Dresden, Germany
| | - Philippe Moisy
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France.
| | | | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Bagnols-sur-Cèze, France.
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Strzelecki AC, Barral T, Estevenon P, Mesbah A, Goncharov V, Baker J, Bai J, Clavier N, Szenknect S, Migdisov A, Xu H, Ewing RC, Dacheux N, Guo X. The Role of Water and Hydroxyl Groups in the Structures of Stetindite and Coffinite, MSiO 4 (M = Ce, U). Inorg Chem 2021; 60:718-735. [PMID: 33393766 DOI: 10.1021/acs.inorgchem.0c02757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Orthosilicates adopt the zircon structure types (I41/amd), consisting of isolated SiO4 tetrahedra joined by A-site metal cations, such as Ce and U. They are of significant interest in the fields of geochemistry, mineralogy, nuclear waste form development, and material science. Stetindite (CeSiO4) and coffinite (USiO4) can be formed under hydrothermal conditions despite both being thermodynamically metastable. Water has been hypothesized to play a significant role in stabilizing and forming these orthosilicate phases, though little experimental evidence exists. To understand the effects of hydration or hydroxylation on these orthosilicates, in situ high-temperature synchrotron and laboratory-based X-ray diffraction was conducted from 25 to ∼850 °C. Stetindite maintains its I41/amd symmetry with increasing temperature but exhibits a discontinuous expansion along the a-axis during heating, presumably due to the removal of water confined in the [001] channels, which shrink against thermal expansion along the a-axis. Additional in situ high-temperature Raman and Fourier transform infrared spectroscopy also confirmed the presence of the confined water. Coffinite was also found to expand nonlinearly up to 600 °C and then thermally decompose into a mixture of UO2 and SiO2. A combination of dehydration and dehydroxylation is proposed for explaining the thermal behavior of coffinite synthesized hydrothermally. Additionally, we investigated high-temperature structures of two coffinite-thorite solid solutions, uranothorite (UxTh1-xSiO4), which displayed complex variations in composition during heating that was attributed to the negative enthalpy of mixing. Lastly, for the first time, the coefficients of thermal expansion of CeSiO4, USiO4, U0.46Th0.54SiO4, and U0.9Th0.1SiO4 were determined to be αV = 14.49 × 10-6, 14.29 × 10-6, 17.21 × 10-6, and 17.23 × 10-6 °C-1, respectively.
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Affiliation(s)
- Andrew C Strzelecki
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,Materials Science and Engineering Program, Washington State University, Pullman 99164, Washington, United States
| | - Thomas Barral
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Paul Estevenon
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France.,CEA, DES, ISEC, DMRC, Univ Montpellier, Site de Marcoule 30207, France
| | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Vitaliy Goncharov
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,Materials Science and Engineering Program, Washington State University, Pullman 99164, Washington, United States.,Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Jason Baker
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Jianming Bai
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton 11973, New York, United States
| | - Nicolas Clavier
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Stephanie Szenknect
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Artaches Migdisov
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Hongwu Xu
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Rodney C Ewing
- Department of Geological Sciences, Stanford University, Stanford 94305, California, United States
| | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Xiaofeng Guo
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,Materials Science and Engineering Program, Washington State University, Pullman 99164, Washington, United States
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Strzelecki AC, Bourgeois C, Kriegsman KW, Estevenon P, Wei N, Szenknect S, Mesbah A, Wu D, Ewing RC, Dacheux N, Guo X. Thermodynamics of CeSiO 4: Implications for Actinide Orthosilicates. Inorg Chem 2020; 59:13174-13183. [PMID: 32871073 DOI: 10.1021/acs.inorgchem.0c01476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Zircon (ZrSiO4, I41/amd) can accommodate actinides, such as thorium, uranium, and plutonium. The zircon structure has been determined for several of the end-member compositions of other actinides, such as plutonium and neptunium. However, the thermodynamic properties of these actinide zircon structure types are largely unknown due to the difficulties in synthesizing these materials and handling transuranium actinides. Thus, we have completed a thermodynamic study of cerium orthosilicate, stetindite (CeSiO4), a surrogate of PuSiO4. For the first time, the standard enthalpy of formation of CeSiO4 was obtained by high temperature oxide melt solution calorimetry to be -1971.9 ± 3.6 kJ/mol. Stetindite is energetically metastable with respect to CeO2 and SiO2 by 27.5 ± 3.1 kJ/mol. The metastability explains the rarity of the natural occurrence of stetindite and the difficulty of its synthesis. Applying the obtained enthalpy of formation of CeSiO4 from this work, along with those previously reported for USiO4 and ThSiO4, we developed an empirical energetic relation for actinide orthosilicates. The predicted enthalpies of formation of AnSiO4 are then determined with a discussion of future strategies for efficiently immobilizing Pu or minor actinides in the zircon structure.
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Affiliation(s)
- Andrew C Strzelecki
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States.,Materials Science and Engineering, Washington State University, Pullman, Washington 99164, United States
| | - Clement Bourgeois
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States
| | - Kyle W Kriegsman
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States
| | - Paul Estevenon
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France.,CEA, DES, ISEC, DMRC, Univ Montpellier, Site de Marcoule 30207, France
| | - Nian Wei
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,College of Physical Science and Technology, Sichuan University, Chengdu 610065, People's Republic of China
| | - Stephanie Szenknect
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France
| | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France
| | - Di Wu
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States.,Materials Science and Engineering, Washington State University, Pullman, Washington 99164, United States.,The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164, United States
| | - Rodney C Ewing
- Department of Geological Sciences, Stanford University, Stanford, California 94305, United States
| | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France
| | - Xiaofeng Guo
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States.,Materials Science and Engineering, Washington State University, Pullman, Washington 99164, United States
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4
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Estevenon P, Welcomme E, Tamain C, Jouan G, Szenknect S, Mesbah A, Poinssot C, Moisy P, Dacheux N. The formation of PuSiO 4 under hydrothermal conditions. Dalton Trans 2020; 49:6434-6445. [PMID: 32355939 DOI: 10.1039/d0dt01183e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Attempts to synthesize plutonium(iv) silicate, PuSiO4, have been made on the basis of results recently reported in the literature for CeSiO4, ThSiO4, and USiO4 under hydrothermal conditions. Although it was not possible to prepare PuSiO4via applying the conditions reported for thorium and uranium, an efficient method of PuSiO4 synthesis was established by applying the conditions optimized for the CeSiO4 system. This method was based on the slow oxidation of plutonium(iii) silicate reactants under hydrothermal conditions at 150 °C in hydrochloric acid (pH = 3-4). These results shed new light on the potential behavior of plutonium in reductive environments, highlighting the representative nature of cerium surrogates when studying plutonium under such conditions and providing some important pieces of information regarding plutonium chemistry in silicate solutions.
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Affiliation(s)
- Paul Estevenon
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France and ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
| | | | | | - Gauthier Jouan
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France
| | - Stephanie Szenknect
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
| | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
| | | | - Philippe Moisy
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France
| | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
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