Stability of Solid Uranyl Peroxides under Irradiation

Fairley, Melissa; Myers, Nicholas M.; Szymanowski, Jennifer E. S.; Sigmon, Ginger E.; Burns, Peter C.; LaVerne, Jay A.

doi:10.1021/acs.inorgchem.9b02132

Cited by 23 publications

(22 citation statements)

References 41 publications

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“…The Raman spectrum for this system has one uranyl–aquo complex peak and two new peaks at 821 and 735 cm –1 . The peak at 821 cm –1 is in agreement with the spectrum for solid studtite found in the literature, 17 , 39 , 58 , 59 and the peak at 735 cm –1 indicates amorphous uranyl peroxide. 58 The solution containing 20 mM U(VI) and 5 M NaCl (green dashes) shows one peak at 865.3 cm –1 but no peak at 871.5 cm –1 , which indicates that the uranyl–aquo complex is quantitatively converted into a complex between U(VI) and Cl – .…”

Section: Resultssupporting

confidence: 89%

“…The peak at 821 cm –1 is in agreement with the spectrum for solid studtite found in the literature, 17 , 39 , 58 , 59 and the peak at 735 cm –1 indicates amorphous uranyl peroxide. 58 The solution containing 20 mM U(VI) and 5 M NaCl (green dashes) shows one peak at 865.3 cm –1 but no peak at 871.5 cm –1 , which indicates that the uranyl–aquo complex is quantitatively converted into a complex between U(VI) and Cl – . According to previous studies, the peak at 865.3 cm –1 is attributed to the disubstituted uranyl–chloro complex UO 2 Cl + .…”

Section: Resultssupporting

confidence: 89%

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Stability of Studtite in Saline Solution: Identification of Uranyl–Peroxo–Halo Complex

Szabó

Jönsson

2022

Inorg. Chem.

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Hydrogen peroxide is produced upon radiolysis of water and has been shown to be the main oxidant driving oxidative dissolution of UO 2 -based nuclear fuel under geological repository conditions. While the overall mechanism and speciation are well known for granitic groundwaters, considerably less is known for saline waters of relevance in rock salt or during emergency cooling of reactors using seawater. In this work, the ternary uranyl–peroxo–chloro and uranyl–peroxo–bromo complexes were identified using IR, Raman, and nuclear magnetic resonance (NMR) spectroscopy. Based on Raman spectra, the estimated stability constants for the identified uranyl–peroxo–chloro ((UO 2 )(O 2 )(Cl)(H 2 O) 2 – ) and uranyl–peroxo–bromo ((UO 2 )(O 2 )(Br)(H 2 O) 2 – ) complexes are 0.17 and 0.04, respectively, at ionic strength ≈5 mol/L. It was found that the uranyl–peroxo–chloro complex is more stable than the uranyl–peroxo–bromo complex, which transforms into studtite at high uranyl and H 2 O 2 concentrations. Studtite is also found to be dissolved at a high ionic strength, implying that this may not be a stable solid phase under very saline conditions. The uranyl–peroxo–bromo complex was shown to facilitate H 2 O 2 decomposition via a mechanism involving reactive intermediates.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 89%

Stability of Studtite in Saline Solution: Identification of Uranyl–Peroxo–Halo Complex

Szabó

Jönsson

2022

Inorg. Chem.

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“…The uranyl oxo is expected to occur at approximately 530 eV and both the nitrate and the ether O atoms have features at 533 and 534 eV, respectively [24,30] . For compound 3 , the peaks occur at 533.5 eV, 530.4, and 528.4 eV, which we assign to the ether/nitrate, uranyl oxo, and peroxide groups, respectively [25a] . There are three peaks within the spectrum for 4 , with peak centroids at 533.5 eV, 530.5 eV, and 528.2 eV.…”

Section: Resultsmentioning

confidence: 82%

Photoinduced Transformation of Uranyl Nitrate Crown Ether Compounds

et al. 2020

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The uranyl cation, (U(VI)O2)2+, has previously demonstrated photocatalytic reactivity in organic solutions, which results in the formation of uranyl peroxide species. Past studies indicated that the phototransformation process typically ends with the formation of uranyl peroxide solid phases. In the current study, we explore the transformation of uranyl nitrate crown ether complexes, (18‐crown‐6)[UO2(NO3)2(H2O)2] ⋅ 2 H2O (1 a), (18‐crown‐6)[UO2(NO3)2(H2O)2] (1 b), and (18‐crown‐6) [K(18‐crown‐6)] [(UO2)2(OH)2(NO3)4(H2O)4] (2) in the presence of ethanol to create a uranyl peroxide intermediate phase, (18‐crown‐6)[(UO2)2(O2)(NO3)2(H2O)4] (3), followed by a second alteration to a black solid (4). These compounds were structurally evaluated using both single‐crystal and powder X‐ray diffraction and then further characterized using Raman, NMR, and XPS spectroscopy. The initial transformation from the yellow uranyl nitrate phase (1 a, 1 b, and 2) to the uranyl peroxide (3) follow previously reported mechanisms. The second transformation to the black phase (4) is likely due to additional degradation of the 18‐crown‐6 molecule as a result of hydrogen abstraction and ring‐opening. In addition, we discuss the nature of confinement effects to impact the hydrogen abstraction process and the possibility that nitrate anions in the system may synergistically enhance the degradation process and lead to the formation of 4.

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“… 43 For example, uranyl-coordination cages, Li 12 K 48 [{(UO 2 )(O 2 )} 60 (C 2 O 4 ) 30 ]· n H 2 O and Li 24 Na 24 [(UO 2 ) 24 (O 2 ) 24 (P 2 O 7 ) 12 ]·120H 2 O, exhibited stability to both γ- and simulated α-irradiation. 43 In contrast to purely-inorganic compounds that could possess long-term stability to ionizing radiation, it is important to investigate the advantages offered by hybrid systems such as An-MOFs, that could be used for short-term manipulation with radionuclides. 44–46 …”

Section: Introductionmentioning

confidence: 99%