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Zhang D, Wang Y, Heng J, Diao X, Zu G, Jin Q, Chen Z, Guo Z. Stability of Eu(III)-silicate colloids: Effect of Eu content, pH, electrolyte and fulvic acid. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129363. [PMID: 35777145 DOI: 10.1016/j.jhazmat.2022.129363] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 05/30/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Dissolved silicic acid in the environment has strong affinity for actinides (An), but An(III)-silicate colloids have been scarcely investigated. In this study, Eu(III)-silicate colloids, an analogue to An(III)-silicate, were prepared and the aggregation kinetics of the colloids was investigated as a function of Eu content (Si/Eu molar ratio), pH, background electrolyte (NaCl, NaNO3, NaClO4, KCl and CsCl) and fulvic acid (FA). Results indicated that the colloids with higher Si/Eu molar ratio exhibited higher stability under the same conditions. The stability of the colloids increased with increasing aqueous pH (7.1-9.4) and decreasing ionic strength, and the inhibition effect of monovalent electrolytes on the colloid stability followed the order of Na+ < K+ < Cs+ and Cl- < NO3- < ClO4-. In addition, the presence of FA significantly increased the stability of the colloids. The dependence of the stability on the chemical conditions in all cases could be illustrated by DLVO theory. Disaggregation kinetics showed that the aggregation process of the colloids was not fully reversible, because a time-dependent size memory effect led to a bigger mean size of disaggregated colloids as compared to the initial ones. The present work provides detailed insight in the formation and stability of An(III)-silicate colloids under the alkaline conditions relevant to geological disposal of radioactive waste, which is critical for understanding the behavior of this type of colloids in the environment.
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Affiliation(s)
- Daming Zhang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Yuxiong Wang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Jiaxi Heng
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Xinya Diao
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Ganlin Zu
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Qiang Jin
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China.
| | - Zongyuan Chen
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China
| | - Zhijun Guo
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China.
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Zhai B, Tian Q, Li N, Yan M, Henderson MJ. SAXS study of the formation and structure of polynuclear thorium(IV) colloids and thorium dioxide nanoparticles. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:281-287. [PMID: 35254289 PMCID: PMC8900854 DOI: 10.1107/s1600577521012923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 12/05/2021] [Indexed: 06/01/2023]
Abstract
Stable actinide colloids and nanoparticles are of interest because of their potential to affect the transportation of radionuclides in the near-field of a nuclear waste repository. At high concentrations, thorium(IV) can precipitate to form intrinsic colloids. In the present study, polynuclear thorium colloids and thorium dioxide crystallites, formed by the condensation of hydrolyzed Th4+ solutions (3 mM; initial pH 5.5) aged for up to 18 months, were studied using small-angle X-ray scattering. Scattering profiles were fitted using a unified Guinier/power-law model (Beaucage model) to extract the radii of gyration and Porod exponents. Analysis of the scattering profiles from a dispersion aged for 5 months indicated that both polymer coils and more compacted structures (radius of gyration Rg ≃ 10 nm) were present, which translated in the Kratky plots as a plateau and a peak maximum, respectively. After 18 months, the SAXS data were consistent with the presence of agglomerates of ThO2 particles suspended in aqueous solution (pH 3.2; [Th] = 1.45 mM). The measured radius of gyration (Rg) of the agglomerates was 5.8 nm, whereas the radius of the ThO2 particles was 2.5 nm.
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Affiliation(s)
- Baihui Zhai
- State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
| | - Qiang Tian
- State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
| | - Na Li
- National Facility for Protein Science in Shanghai, Zhangjiang Laboratory, Shanghai 201204, People’s Republic of China
| | - Minhao Yan
- State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
| | - Mark J. Henderson
- State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, People’s Republic of China
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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, 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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