uranium species
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2021 ◽  
Author(s):  
K U Rempel ◽  
A E Williams-Jones ◽  
K Fuller

Experimental data on the solubility and speciation of uranium in hydrothermal solution is required to improve genetic models for the formation of ore deposits, yet very few data of this type have been published. Of particular interest is the oxidation state of the uranium in solution, as conventional wisdom suggests that U is dissolved in the oxidized U(VI) state and precipitated as reduced U(IV) minerals, yet recent experiments have shown ppm-level solubility for U(IV). This study investigated the mobility of reduced U(IV) and oxidized U(VI) in acidic (pH = 2), fluoride- bearing and alkaline (pH = 10), chloride-bearing solutions at 100-200°C and 1 to 15.8 bars (0.1-1.58 MPa). Preliminary data for the mobility of U(IV) in pH 2 fluids with 0.01 m F- show concentrations of 1.76 to 3.92 ppm U at 200°C, indicating that, contrary to common belief, the reduced U(IV) can be transported in solution. We have also conducted experiments on U(VI) solubility in pH 2 fluoride-bearing, and pH 10 chloride-bearing solutions. Uranium concentrations in the F- -bearing experiments ranged from 624 to 1570 ppm (avg. 825 ppm, n = 6) at 100°C, 670 to 1560 ppm (avg. 931 ppm, n = 4) at 150°C, and 3180 to 7550 ppm (avg. 5240, n = 9) at 200°C. In comparison, U concentrations in the Cl- -bearing runs range from 86.1 to 357 ppm (avg. 185 ppm, n = 15) at 200°C. Clearly, oxidized U(VI) is very readily mobilized in hydrothermal fluids. However, the measured concentrations of U(VI) are independent of those of F- or Cl-, suggesting the formation of U oxide or hydroxide species rather than U chlorides or fluorides. These experimental data will be verified and supplemented in future experiments, which will be used to derive the stoichiometry and thermodynamic constants for the dominant uranium species in hydrothermal solutions. The data from this study will then be integrated into a comprehensive genetic model for uranium ore-forming systems.



2020 ◽  
Vol 32 (1) ◽  
pp. 8-13
Author(s):  
Danielle R. Mannion ◽  
Joseph M. Mannion ◽  
Wendy W. Kuhne ◽  
Matthew S. Wellons
Keyword(s):  




2020 ◽  
Vol 39 (2) ◽  
pp. 353-360
Author(s):  
Caleb J. Tatebe ◽  
Ellen M. Matson ◽  
Christopher L. Clark ◽  
John J. Kiernicki ◽  
Phillip E. Fanwick ◽  
...  
Keyword(s):  


2020 ◽  
Vol 49 (3) ◽  
pp. 578-582 ◽  
Author(s):  
Tara K. K. Dickie ◽  
Connor S. MacNeil ◽  
Paul G. Hayes

A uranium(iv) complex supported by an unusual diphosphazide ligand was prepared. Controlled, consecutive N2 loss was observed, affording well-defined uranium species that were characterized by multinuclear NMR spectroscopy and X-ray crystallography.



2019 ◽  
Vol 53 (16) ◽  
pp. 9361-9369 ◽  
Author(s):  
Gabrielle Dublet ◽  
Isabelle Worms ◽  
Manon Frutschi ◽  
Ashley Brown ◽  
Giada C. Zünd ◽  
...  
Keyword(s):  


2019 ◽  
Vol 48 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Justin K. Pagano ◽  
David S. J. Arney ◽  
Brian L. Scott ◽  
David E. Morris ◽  
Jaqueline L. Kiplinger ◽  
...  
Keyword(s):  

Three new uranium species, (C5Me5)2U(N-2,6-iPr2-C6H3)(S), (C5Me5)2U(N-2,6-iPr2-C6H3)(η2-S2), and (C5Me5)2U(N-2,6-iPr2-C6H3)(SPMe3) have been prepared.



2019 ◽  
Vol 7 (2) ◽  
pp. 664-678 ◽  
Author(s):  
Raj Kumar Dutta ◽  
Md. Azfar Shaida ◽  
Kirti Singla ◽  
Dipika Das

Development of RGO-AMP for fast, selective and unprecedented adsorption of uranium species with qmax = 3024 mg g−1.



Chemosphere ◽  
2018 ◽  
Vol 208 ◽  
pp. 846-853 ◽  
Author(s):  
Haiying Fu ◽  
Hui Zhang ◽  
Yang Sui ◽  
Nan Hu ◽  
Dexin Ding ◽  
...  
Keyword(s):  


2018 ◽  
Vol 19 (3) ◽  
pp. 789-795 ◽  
Author(s):  
Youngkun Chung ◽  
Yeo-Myeong Yun ◽  
Yeo-Jin Kim ◽  
Yu Sik Hwang ◽  
Seoktae Kang

Abstract In this research, ceramic nanofiltration (NF) membranes were prepared by depositing alumina-zirconia (Al-Zr) nanoparticles into the pores of ceramic ultrafiltration (UF) membranes for the removal of radioactive uranium in an aquatic system. The modified ceramic membranes showed NF membrane performance with around 1,000 Da molecular weight cut-off (MWCO) and 58% CaCl2 rejection. The removal efficiencies of uranium species by these successfully modified ceramic NF membranes exhibited differences depending on the pH conditions (pH 5.0, 7.4, and 10.0), and achieved the highest rejection of 91% at pH 7.4. This behavior is due to the dominant aqueous species of uranium in pH 7.4, (UO2)2CO3(OH3)−, which has the largest molecular weight among the conditions and the negatively charged species having electrostatic attraction to the positively charged ceramic NF membranes. The ceramic NF membrane prepared here is expected to be feasible in the advanced water treatment process to remove radioactive compounds.



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