New insight into the ternary complexes of uranyl carbonate in seawater

Beccia, Maria Rosa; Matara-aho, Minja; Reeves, Benjamin D.; Roques, Jérôme; Solari, Pier Lorenzo; Monfort, Marguerite; Moulin, Christophe; Auwer, Christophe Den

doi:10.1016/j.jenvrad.2017.08.008

Cited by 9 publications

(6 citation statements)

References 22 publications

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“…The reason for the increase of the triscarbonatouranyl species luminescence intensity in the presence of calcium is still unclear and may originate from either favorable vibronic coupling or diminution of quenching effects from the carbonate ion. Similar observations have been made with the less stable ternary MgUO 2 (CO 3 ) 3 2– and SrUO 2 (CO 3 ) 3 2– complexes, , while the confirmation of the existence of the ternary Mg 2 UO 2 (CO 3 ) 3 complex is still discussed. ,, …”

Section: Introductionsupporting

confidence: 76%

“…34 The reason for the increase of the triscarbonatouranyl species luminescence intensity in the presence of calcium is still unclear and may originate from either favorable vibronic coupling or diminution of quenching effects from the carbonate ion. Similar observations have been made with the less stable ternary MgUO 2 (CO 3 ) 3 2− and SrUO 2 (CO 3 ) 3 2− complexes, 35,36 while the confirmation of the existence of the ternary Mg 2 UO 2 (CO 3 ) 3 complex is still discussed. 26,31,35 Quantum chemical modeling is an appropriate theoretical support for a better understanding of the luminescence of these ternary triscarbonatouranyl complexes with alkaline earth metal cations.…”

Section: ■ Introductionmentioning

confidence: 99%

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Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of Na_mM_nUO₂(CO₃)₃^{(4–m–2n)–} (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

et al. 2020

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HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires Influence of alkaline earth metal ions on structures and luminescent properties of Na m M n UO 2 (CO 3) 3 (4-m-2n)-(M = Mg, Ca; m, n = 0-2): time-resolved fluorescence spectroscopy and ab initio studies

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Section: Introductionsupporting

confidence: 76%

Section: ■ Introductionmentioning

confidence: 99%

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of Na_mM_nUO₂(CO₃)₃^{(4–m–2n)–} (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

et al. 2020

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“…It goes from UO2 2+ to UO2(OH)i] 2-i under saline (NaCl) water conditions or [UO2(CO3)3] 4in solution with NaHCO3, potentially [Ca(UO2)(CO3)3] 2and [Ca2(UO2)(CO3)3] in a Na(Ca)HCO3 water as reported by Moulin et al (1990). This was confirmed for artificial seawater by Beccia et al (2017).…”

Section: Speciation In Tic Solution and Their Effect On Sorptionsupporting

confidence: 57%

Simulating uranium sorption onto inorganic particles: The effect of redox potential

Degueldre

McGowan

2020

Journal of Environmental Radioactivity

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An analytical expression is proposed to simulate the effects of pH and redox potential (E) on the sorption of uranium onto model inorganic particles in aquatic environments instead of following an experimental approach providing a list of empirical sorption data. The expression provides a distribution coefficient (Kd) as function of pH, E and ligand concentration (complex formation) applying a surface complexation model on one type of surface sites (>SuOH). The formulation makes use of the complexation and hydrolysis constants for all species in solution and those sorbed at the surface, using correlations between hydrolysis constants and surface complexation constants, for the specific sorption sites. The model was applied for the sorption of uranium onto aluminol, iron hydroxide and silanol sites, mimicking respectively 'clean' clay or 'dirty' clay and 'clean' sand or 'dirty' sand ('dirty' referring to iron hydroxide contaminated), in absence or presence of carbonates in solution. The calculated distribution coefficients are very sensitive with the presence or absence of carbonates. The Kd values obtained by applying the model are compared with values reported in the literature for the sorption of uranium onto specific adsorbents. It is known that in surface water, U(VI) and its hydroxides are the primary stable species usually observed. However, reduction to U(IV) is possible and may be simulated during sorption or when the redox potential (E) decreases.Similar simulations are also applicable to study the sorption of other redox sensitive elements.

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“…Similar alkaline earth U(VI) triscarbonato complexes are significant in environmental scenarios and have a range of potential counterions, including Ca 2+ , Na + , and Sr 2+ . Interestingly, the soluble Ca analogue of this species, Ca(UO 2 (CO 3 ) 3 ) 2– (aq) , as well as Ca 2 (UO 2 (CO 3 ) 3 ) 0 (aq) , is reportedly significant in calcite–U(VI) systems under circumneutral conditions. , Indeed, it was reported that the presence of these aqueous species prevented solid U(VI) precipitation onto the surface of the calcite, with monomeric surface complexes forming preferentially. ,, Other studies have also reported that the formation of alkaline earth uranyl triscarbonate species inhibits solid U(VI) precipitation onto various mineral surfaces. ,, The results in this study indicate that similar changes in U(VI) sorption behavior occur in the hydrotalcite–U(VI) systems under more circumneutral conditions, with Mg leaching and the exchange of interlayer carbonate resulting in the formation of U(VI) carbonate species such as Mg(UO 2 (CO 3 ) 3 ) 2– (aq) and UO 2 (CO 3 ) 3 4– (aq) . The presence of these anionic species then favors the formation of monomeric surface complexes rather than U(VI) surface precipitates.…”

Section: Resultsmentioning

confidence: 99%

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

et al. 2022

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In the United Kingdom, decommissioning of legacy spent fuel storage facilities involves the retrieval of radioactive sludges that have formed as a result of corrosion of Magnox nuclear fuel. Retrieval of sludges may re-suspend a colloidal fraction of the sludge, thereby potentially enhancing the mobility of radionuclides including uranium. The colloidal properties of the layered double hydroxide (LDH) phase hydrotalcite, a key product of Magnox fuel corrosion, and its interactions with U(VI) are of interest. This is because colloidal hydrotalcite is a potential transport vector for U(VI) under the neutral-to-alkaline conditions characteristic of the legacy storage facilities and other nuclear decommissioning scenarios. Here, a multi-technique approach was used to investigate the colloidal stability of hydrotalcite and the U(VI) sorption mechanism(s) across pH 7–11.5 and with variable U(VI) surface loadings (0.01–1 wt %). Overall, hydrotalcite was found to form stable colloidal suspensions between pH 7 and 11.5, with some evidence for Mg 2+ leaching from hydrotalcite colloids at pH ≤ 9. For systems with U present, >98% of U(VI) was removed from the solution in the presence of hydrotalcite, regardless of pH and U loading, although the sorption mode was affected by both pH and U concentrations. Under alkaline conditions, U(VI) surface precipitates formed on the colloidal hydrotalcite nanoparticle surface. Under more circumneutral conditions, Mg 2+ leaching from hydrotalcite and more facile exchange of interlayer carbonate with the surrounding solution led to the formation of uranyl carbonate species (e.g., Mg(UO 2 (CO 3 ) 3 ) 2– (aq) ). Both X-ray absorption spectroscopy (XAS) and luminescence analysis confirmed that these negatively charged species sorbed as both outer- and inner-sphere tertiary complexes on the hydrotalcite surface. These results demonstrate that hydrotalcite can form pseudo-colloids with U(VI) under a wide range of pH conditions and have clear implications for understanding the uranium behavior in environments where hydrotalcite and other LDHs may be present.

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New insight into the ternary complexes of uranyl carbonate in seawater

Cited by 9 publications

References 22 publications

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of Na_mM_nUO₂(CO₃)₃^{(4–m–2n)–} (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of Na_mM_nUO₂(CO₃)₃^{(4–m–2n)–} (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

Simulating uranium sorption onto inorganic particles: The effect of redox potential

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

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New insight into the ternary complexes of uranyl carbonate in seawater

Cited by 9 publications

References 22 publications

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of NamMnUO2(CO3)3(4–m–2n)– (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of NamMnUO2(CO3)3(4–m–2n)– (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

Simulating uranium sorption onto inorganic particles: The effect of redox potential

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

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Product

Resources

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Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of Na_mM_nUO₂(CO₃)₃^{(4–m–2n)–} (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies

Influence of Alkaline Earth Metal Ions on Structures and Luminescent Properties of Na_mM_nUO₂(CO₃)₃^{(4–m–2n)–} (M = Mg, Ca; m, n = 0–2): Time-Resolved Fluorescence Spectroscopy and Ab Initio Studies