Adsorption of uranyl tricarbonate and calcium uranyl carbonate onto γ-alumina

Jo, Yongheum; Lee, Jun-Yeop; Yun, Jong-Il

doi:10.1016/j.apgeochem.2018.05.004

Cited by 22 publications

(11 citation statements)

References 37 publications

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“…Additionally, the 4 nm red shift between the spectral features of the 0.01 wt % sample relative to the 1 wt % sample indicates changes in the relative proportions of the outer- and inner-sphere complexes, with inner-sphere complexes becoming more significant as the U(VI) loading is reduced . A similar shift was observed by Jo et al, who found that the spectrum for U(VI) inner-sphere sorbed onto the surface of γ-alumina was red-shifted by approximately 4 nm when compared to that of an aqueous Ca triscarbonato species …”

Section: Resultssupporting

confidence: 73%

“… 86 A similar shift was observed by Jo et al, who found that the spectrum for U(VI) inner-sphere sorbed onto the surface of γ-alumina was red-shifted by approximately 4 nm when compared to that of an aqueous Ca triscarbonato species. 76 …”

Section: Resultsmentioning

confidence: 99%

“…The luminescence spectra from the hydrotalcite colloids at pHs 11.5, 9, and 7 and U loadings of 0.01 and 1 wt % are provided in Figure along with published luminescence spectra for compreignacite, calcium uranate, and aqueous uranyl triscarbonate. − The key spectral features and luminescence lifetime values obtained via tail fitting are provided in Table S7. The luminescence spectrum for the pH 9 1 wt % U(VI) sample showed key peaks at 514 nm (19 455 cm –1 ) and 536 nm (18 657 cm –1 ), with a shoulder feature located at 556 nm (17 986 cm –1 ) (Figure ).…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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

et al. 2022

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“…Uranyl ions are distributed not only in the solution but also on the solid matrix surface under certain conditions. , For example, the instruments or mechanical equipment running in radioactive working places will inevitably adsorb uranyl compounds when they are engage in nuclear-related works or nuclear accidents happen, causing health hazard to the workers. Thus, in situ monitoring of the uranyl ion absorbed on these surfaces is significant and meaningful.…”

Section: Results and Discussionmentioning

confidence: 99%

In Situ Surface-Enhanced Raman Spectroscopy Detection of Uranyl Ions with Silver Nanorod-Decorated Tape

et al. 2019

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Surface-enhanced Raman spectroscopy (SERS) has been utilized for rapid analysis of uranyl ions (UO 2 2+ ) on account of its fast response and high sensitivity. However, the difficulty of fabricating a suitable SERS substrate for in situ analysis of uranyl ions severely restricts its practical application. Hence, we proposed flexible and adhesive SERS tape decorated with silver nanorod (AgNR) arrays for in situ detection of UO 2 2+ . The SERS tape was fabricated through a simple “paste & peel off” procedure by transferring the slanted AgNR arrays from silicon to the transparent tape surface. UO 2 2+ can be easily in situ detected by placing the AgNR SERS tape into an aqueous solution or pasting it onto the solid matrix surface due to the excellent transparent feature of the tape. The proposed SERS tape with well-distributed AgNRs effectively improved the reproducibility and sensitivity for UO 2 2+ analysis. UO 2 2+ with concentration as low as 100 nM was easily detected. Besides, UO 2 2+ adsorbed on an iron disc and rock surface also can be rapidly in situ detected. With its simplicity and convenience, the AgNR SERS tape-based SERS technique offers a promising approach for environmental monitoring and nuclear accident emergency detection.

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“…For the reliable safety assessment of a radioactive waste repository, a systematic understanding of the migration behavior of radionuclides is essential, because a key criterion for an appropriate disposal strategy is the capability to isolate the harmful substances [1]. Various geochemical reactions such as aqueous complexation [2,3], solubility [4][5][6], sorption [7,8], etc. can be quantitatively predicted by using relevant chemical thermodynamic data such as formation constant, solubility product constant, etc.…”

Section: Introductionmentioning

confidence: 99%

Impact of Updated OECD/NEA Thermodynamic Database on the Safety Assessment of Radioactive Waste Repository Studied Using RESRAD-OFFSITE Code

2021

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A RESRAD-OFFISTE computational code for the safety assessment model of a radioactive waste repository was utilized to evaluate the influence of the updated OECD/NEA thermodynamic database on the safety assessment model in terms of exposure dose. The solubility data as the input parameter for the RESRAD-OFFSITE code obtained with two different sets of chemical thermodynamic databases such as JAEA-TDB and amended JAEA-TDB reflecting the updates of the OECD/NEA thermodynamic database were calculated and compared with each other. As a result, almost identical exposure doses were obtained due to the remarkable similarity between the solubility data of various radionuclides for both chemical thermodynamic databases. In contrast, dramatic changes in exposure dose were observed with varying distribution coefficients. Thermodynamic calculations indicated that the aqueous species distribution can be significantly changed by the selection of a chemical thermodynamic database and thus the relevant distribution coefficient can also be influenced as a consequence. Accordingly, the result obtained in the present work indicated that (i) the impact of the updated chemical thermodynamic data was somewhat minor from the viewpoint of the solubility and (ii) the distribution coefficient, which can be sensitively influenced by the predominant chemical species, produced a remarkable change in the exposure dose. This work provided an insight into the precise exposure dose calculation in terms of the reliable estimation of the distribution coefficient by means of a surface complexation model, which can predict the distribution coefficient as a function of groundwater composition coupled with a chemical speciation calculation based on up to date chemical thermodynamic data.

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Adsorption of uranyl tricarbonate and calcium uranyl carbonate onto γ-alumina

Cited by 22 publications

References 37 publications

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

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

In Situ Surface-Enhanced Raman Spectroscopy Detection of Uranyl Ions with Silver Nanorod-Decorated Tape

Impact of Updated OECD/NEA Thermodynamic Database on the Safety Assessment of Radioactive Waste Repository Studied Using RESRAD-OFFSITE Code

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