OSTI.GOV Journal Article: A spectroscopic study of uranyl speciation in chloride-bearing solutions at temperatures up to 250 °C
Title: A spectroscopic study of uranyl speciation in chloride-bearing solutions at temperatures up to 250 °C
The speciation of U in NaCl-bearing solutions at temperatures up to 250 °C and concentrations of NaCl up to 1.5 m has been investigated using an in situ spectroscopic technique. The recorded spectra permit us to identify the species present in the solutions as UO 2 2+, UO 2Cl +, and UO 2Cl 2°. UO 2Cl 3 - is also likely present at high temperatures and NaCl concentrations, but concentrations of this species are insufficient for derivation of the formation constants. No evidence was found for species of higher ligand (Cl-) number. Thermodynamic stability constants derived for these species show fair agreement with published data for 25 °C, but differ significantly from those predicted by an earlier high-temperature study (Dargent et al., 2013), which suggested that UO 2Cl 4 2- and UO 2Cl 5 3- contribute significantly to the mass balance of uranyl chloride complexes, especially at high temperature. In contrast, our data suggest that the main uranyl-chloride complex present in aqueous solutions at T >150 °C and concentrations of NaCl relevant to natural hydrothermal systems is UO 2Cl 2°. The values of the logarithms of thermodynamic formation constants (β) for the reaction UO 2 2+ + Cl - =more » UO 2Cl + are 0.02, 0.25, 0.55, 1.09, 1.59, and 2.28 derived at 25, 50, 100, 150, 200, and 250 °C, respectively. For the reaction UO 2 2+ + 2Cl - = UO 2Cl 2° the values of log β derived at these temperatures are 0.4, 0.58, 0.74, 1.44, 2.18, and 3.42. Values of the formation constant estimated for uranyl-chloride species predict the high concentrations of U observed by Richard et al. (2011) in fluid inclusions of the giant McArthur River unconformity-type uranium deposit.« less
Migdisov, A. A. [1];
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Search OSTI.GOV for ORCID "0000-0001-7734-2082"
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Boukhalfa, H. [1];
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Timofeev, A. [2]; Runde, W. [1]; Roback, R. [1];
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Williams-Jones, A. E. [2]
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
McGill Univ., Montreal, QC (Canada). Dept. of Earth and Planetary Sciences
USDOE Office of Nuclear Energy (NE)
Alternate Identifier(s):
OSTI ID: 1635277
LA-UR-17-23808
Journal ID: ISSN 0016-7037; TRN: US1702906
AC52-06NA25396
Journal Volume: 222; Journal ID: ISSN 0016-7037
The Geochemical Society; The Meteoritical Society
58 GEOSCIENCES; uranyl; chloride; hydrothermal; speciation; aqueous solution
Migdisov, A. A., Boukhalfa, H., Timofeev, A., Runde, W., Roback, R., and Williams-Jones, A. E. A spectroscopic study of uranyl speciation in chloride-bearing solutions at temperatures up to 250 °C. United States: N. p., 2017. Web. doi:10.1016/j.gca.2017.10.016.
Migdisov, A. A., Boukhalfa, H., Timofeev, A., Runde, W., Roback, R., & Williams-Jones, A. E. A spectroscopic study of uranyl speciation in chloride-bearing solutions at temperatures up to 250 °C. United States. https://doi.org/10.1016/j.gca.2017.10.016
Migdisov, A. A., Boukhalfa, H., Timofeev, A., Runde, W., Roback, R., and Williams-Jones, A. E. Tue . "A spectroscopic study of uranyl speciation in chloride-bearing solutions at temperatures up to 250 °C". United States. https://doi.org/10.1016/j.gca.2017.10.016. https://www.osti.gov/servlets/purl/1406219.
title = {A spectroscopic study of uranyl speciation in chloride-bearing solutions at temperatures up to 250 °C},
author = {Migdisov, A. A. and Boukhalfa, H. and Timofeev, A. and Runde, W. and Roback, R. and Williams-Jones, A. E.},
abstractNote = {The speciation of U in NaCl-bearing solutions at temperatures up to 250 °C and concentrations of NaCl up to 1.5 m has been investigated using an in situ spectroscopic technique. The recorded spectra permit us to identify the species present in the solutions as UO22+, UO2Cl+, and UO2Cl2°. UO2Cl3- is also likely present at high temperatures and NaCl concentrations, but concentrations of this species are insufficient for derivation of the formation constants. No evidence was found for species of higher ligand (Cl-) number. Thermodynamic stability constants derived for these species show fair agreement with published data for 25 °C, but differ significantly from those predicted by an earlier high-temperature study (Dargent et al., 2013), which suggested that UO2Cl42- and UO2Cl53- contribute significantly to the mass balance of uranyl chloride complexes, especially at high temperature. In contrast, our data suggest that the main uranyl-chloride complex present in aqueous solutions at T >150 °C and concentrations of NaCl relevant to natural hydrothermal systems is UO2Cl2°. The values of the logarithms of thermodynamic formation constants (β) for the reaction UO22+ + Cl- = UO2Cl+ are 0.02, 0.25, 0.55, 1.09, 1.59, and 2.28 derived at 25, 50, 100, 150, 200, and 250 °C, respectively. For the reaction UO22+ + 2Cl- = UO2Cl2° the values of log β derived at these temperatures are 0.4, 0.58, 0.74, 1.44, 2.18, and 3.42. Values of the formation constant estimated for uranyl-chloride species predict the high concentrations of U observed by Richard et al. (2011) in fluid inclusions of the giant McArthur River unconformity-type uranium deposit.},
doi = {10.1016/j.gca.2017.10.016},
url = {https://www.osti.gov/biblio/1406219}, journal = {Geochimica et Cosmochimica Acta},
volume = 222,
Accepted Manuscript (Publisher)
https://doi.org/10.1016/j.gca.2017.10.016
Uranium transport in acidic brines under reducing conditions
Timofeev, Alexander; Migdisov, Artaches A.; Williams-Jones, Anthony E.
Nature Communications, Vol. 9, Issue 1
Uranium Transport in F-Cl-Bearing Fluids and Hydrothermal Upgrading of U-Cu Ores in IOCG Deposits
Xing, Yanlu; Mei, Yuan; Etschmann, Barbara
Geofluids, Vol. 2018
A spectrophotometric study of aqueous iron (II) chloride complexing from 25 to 200 degree C
Journal Article Heinrich, C A ; Seward, T M - Geochimica et Cosmochimica Acta; (USA)
Ultraviolet absorption spectra of solutions in the system FeCl{sub 2}-HCl-H{sub 2}O with chloride concentrations ranging from 0.01 to 3.4 m and Fe(II) concentrations ranging from 0.005 to 0.025 m have been measured at 25, 50, 100, 150, and 200{degree}C and the equilibrium saturation vapor pressure of the system. Non-linear least squares regression was used to estimate cumulative thermodynamic association constants and molar absorptivities. At 25, 50, and 100{degree}C, only Fe{sup 2+} and FeCl{sup +} are detectable, whereas at higher temperatures a minor concentration of a third species, interpreted to be FeCl{sup 0}{sub 2}, starts to contribute substantially to total absorbance.more » Recommended values of the association constants, {beta}{sub 1} and {beta}{sub 2}, for the equilibria Fe{sup 2+} + Cl{sup {minus}} = FeCl{sup +} and Fe{sup 2+} + 2Cl{sup {minus}} = FeCl{sup 0}{sub 2} are given. In combination with published thermodynamic data for the Fe-S-O-H system, the equilibrium formation constants are used to calculate solubilities of selected Fe mineral assemblages in NaCl-rich hydrothermal solutions. The results are in satisfactory agreement with published analytical data from basinal brines and geothermal fluids.« less
https://doi.org/10.1016/0016-7037(90)90046-N
Multi-scale modelling of uranyl chloride solutions
Journal Article Nguyen, Thanh-Nghi ; Duvail, Magali ; Villard, Arnaud ; ... - Journal of Chemical Physics
Classical molecular dynamics simulations with explicit polarization have been successfully used to determine the structural and thermodynamic properties of binary aqueous solutions of uranyl chloride (UO{sub 2}Cl{sub 2}). Concentrated aqueous solutions of uranyl chloride have been studied to determine the hydration properties and the ion-ion interactions. The bond distances and the coordination number of the hydrated uranyl are in good agreement with available experimental data. Two stable positions of chloride in the second hydration shell of uranyl have been identified. The UO{sub 2}{sup 2+}-Cl{sup −} association constants have also been calculated using a multi-scale approach. First, the ion-ion potential averagedmore » over the solvent configurations at infinite dilution (McMillan-Mayer potential) was calculated to establish the dissociation/association processes of UO{sub 2}{sup 2+}-Cl{sup −} ion pairs in aqueous solution. Then, the association constant was calculated from this potential. The value we obtained for the association constant is in good agreement with the experimental result (K{sub UO{sub 2Cl{sup +}}} = 1.48 l mol{sup −1}), but the resulting activity coefficient appears to be too low at molar concentration.« less
Spectrophotometric investigation of U(VI) chloride complexation in the NaCl/NaClO{sub 4} system
Technical Report Paviet-Hartmann, P ; Lin, M R ; Runde, W H
The option of a nuclear waste disposal in deep salt formations such as Gorleben in Germany, and the WIPP (Waste Isolation Pilot Plant) in southeastern New Mexico, US has generated, over the last ten years, interests in thermodynamic data of radioactive trace elements in concentrated electrolyte solutions. Furthermore, post closure radioactive release scenarios from geologic salt formation, such as the WIPP include hydrologic transport of radionuclides through a chloride saturated aquifer. Consequently, the understanding of actinide solution chemistry in brines is essential for modeling requiring accurate knowledge of the interaction between AnO{sub 2}{sup 2+} and chloride ions. The goal ismore » to develop models capable of predicting their behavior in natural multicomponent brines of high concentration. Complexation constants of two U(VI) chloride species, UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0}, have been intensively studied for about 40 years using different methods. However, large uncertainties reflect the general difficulty in determining accurate stability constants of weak complexes. In order to model the behavior of U(VI) in brines, the authors studied the formation of its chloride complexes by UV-Vis spectroscopy as a function of the NaCl concentration at 25 C.« less
Uranyl speciation in sulfate-bearing hydrothermal solutions up to 250 °C
Journal Article Kalintsev, Alexander ; Migdisov, Artaches ; Xu, Hongwu ; ... - Geochimica et Cosmochimica Acta
The speciation of uranyl in sulfate-bearing solutions at temperatures up to 250 ºC has been investigated using in situ UV-Visible spectrophotometry. Formation constants for the reactions UO$$^{2+}_{2}$$ + SO$$^{2–}_{4}$$ $$\Longleftrightarrow$$ UO 2SO$$^{0}_{4}$$ (logβ 1 = 3.38, 4.40, 5.44, 6.33, 7.74) and UO$$^{2+}_{2}$$ + 2SO$$^{2–}_{4}$$ $$\Longleftrightarrow$$ UO 2(SO 4)$$^{2–}_{2}$$ (logβ 2 = 4.10, 5.26, 6.83, 8.00, 9.70) derived at 25, 100, 150, 200 and 250 ºC respectively. These formation constants were fitted to the modified Ryzhenko – Bryzgalin (MRB) model to derive pK(298), A(zz/a) and B(zz/a) values for both complexes: 3.262, 2.212, -197.96 (UO 2SO$$^{0}_{4}$$) and 4.189, 3.21, -473.14 UO 2(SOmore » 4)$$^{2–}_{2}$$ respectively. Compared with values extrapolated using previously available data for 25, 70 and 75 ºC, our new data suggest higher stability of UO 2SO$$^{0}_{4}$$ at temperatures above 150 ºC and significantly lower stability of UO 2(SO 4)$$^{2–}_{2}$$ at all temperatures above 25Cº. Molar absorbances of both sulfate species were also derived. At 25 Cº we found our molar absorbance for UO 2SO$$^{0}_{4}$$ agreed well with those reported previously in the literature, however we report lower peak amplitudes for UO 2(SO 4)$$^{2–}_{2}$$ . We also noted significant temperature-dependent red shifts in the molar absorbance of UO 2SO$$^{0}_{4}$$. We imply that these shifts could be explained by changes in sulfate bonding behaviour around the uranyl O04 ion - namely shifts in the distribution of complexes with sulfate bound in either a monodentate or bidentate configuration. Simple models calculated with our new data suggest that sulfate complexes may readily predominate over chloride complexes even in solutions containing upwards of 20 wt% chloride and only 100 ppm sulfate. In addition, moderate concentrations of sulfate (~1 wt%) can increase the solubility of uranium by an order of magnitude. Therefore, we imply that sulfate could play a vital role in mobilising uranium in hydrothermal systems, and that the removal of sulfate via precipitation of sulfate minerals may act as a means of depositing uranium under oxidizing conditions. This in turn might explain the associations between sulfate minerals and uranium mineralisation occasionally seen in large uranium ore deposits such as Olympic Dam and MacArthur River.« less
Solubility Model for Ferrous Iron Hydroxide, Hibbingite, Siderite, and Chukanovite in High Saline Solutions of Sodium Chloride, Sodium Sulfate, and Sodium Carbonate
Journal Article Kim, Sungtae ; Marrs, Cassandra ; Nemer, Martin ; ... - ACS Earth and Space Chemistry
Here, a solubility model is presented for ferrous iron hydroxide (Fe(OH) 2(s)), hibbingite (Fe 2Cl(OH) 3(s)), siderite (FeCO 3(s)), and chukanovite (Fe 2CO 3(OH) 2(s)). The Pitzer activity coefficient equation was utilized in developing the model to account for the excess free energies of aqueous species in the background solutions of high ionic strength. Solubility limiting minerals were analyzed before and after experiments using X-ray diffraction. Formation of Fe(OH) 2(s) was observed in the experiments that were initiated with Fe 2Cl(OH) 3(s) in Na 2SO 4 solution. Coexistence of siderite and chukanovite was observed in the experiments in Na 2COmore » 3 + NaCl solutions. Two equilibrium constants that had been reported by us for the dissolution of Fe(OH) 2(s) and Fe 2Cl(OH) 3(s) (Nemer et al.) were rederived in this paper, using newer thermodynamic data selected from the literature to maintain internal consistency of the series of our data analyses in preparation, including this paper. Three additional equilibrium constants for the following reactions were determined in this paper: dissolution of siderite and chukanovite and dissociation of the aqueous species Fe(CO 3) 2 –2. Five Pitzer interaction parameters were derived in this paper: β (0), β (1), and C φ parameters for the species pair Fe +2/SO 4 –2; β (0) and β (1) parameters for the species pair Na+/Fe(CO3)2–2. Our model predicts that, among the four inorganic ferrous iron minerals, siderite is the stable mineral in two WIPP-related brines (WIPP: Waste Isolation Pilot Plant), i.e., GWB and ERDA6 (Brush and Domski), and the electrochemical equilibrium between elemental iron and siderite provides a low oxygen fugacity (10 –91.2 atm) that can keep the actinides at their lowest oxidation states. (Nemer et al., Brush and Domski; references numbered 1 and 2 in the main text).« less
https://doi.org/10.1021/acsearthspacechem.7b00065