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Temperature-Dependent Hydrolysis Reactions of U(VI) Studied by TRLFS

  • Lee, J.Y. (Korea Advanced Institute of Science and Technology) ;
  • Yun, J.I. (Korea Advanced Institute of Science and Technology)
  • Received : 2013.07.11
  • Accepted : 2013.08.26
  • Published : 2013.10.30

Abstract

Temperature-dependent hydrolysis behaviors of aqueous U(VI) species were investigated with time-resolved laser fluorescence spectroscopy (TRLFS) in the temperature range from 15 to $75^{\circ}C$. The formation of four different U(VI) hydrolysis species was measured at pHs from 1 to 7. The predominant presence of $UO{_2}^{2+}$, $(UO_2)_2(OH){_2}^{2+}$, $(UO_2)_3(OH){_5}^+$, and $(UO_2)_3(OH){_7}^-$ species were identified based on the spectroscopic properties such as fluorescence wavelengths and fluorescence lifetimes. With an increasing temperature, a remarkable decrement in the fluorescence lifetime for all U(VI) hydrolysis species was observed, representing the dynamic quenching behavior. Furthermore, the increase in the fluorescence intensity of the further hydrolyzed U(VI) species was clearly observed at an elevated temperature, showing stronger hydrolysis reactions with increasing temperatures. The formation constants of the U(VI) hydrolysis species were calculated to be $log\;K{^0}_{2,2}=-4.0{\pm}0.6$ for $(UO_2)_2(OH){_2}^{2+}$, $log\;K{^0}_{3,5}=-15.0{\pm}0.3$ for $(UO_2)_3(OH){_5}^+$, and $log\;K{^0}_{3,7}=-27.7{\pm}0.7$ for $(UO_2)_3(OH){_7}^-$ at $25^{\circ}C$ and I = 0 M. The specific ion interaction theory (SIT) was applied for the extrapolation of the formation constants to infinitely diluted solution. The results of temperature-dependent hydrolysis behavior in terms of the U(VI) fluorescence were compared and validated with those obtained using computational methods (DQUANT and constant enthalpy equation). Both results matched well with each other. The reaction enthalpies and entropies that are vital for the computational methods were determined by a combination of the van't Hoff equation and the Gibbs free energy equation. The temperature-dependent hydrolysis reaction of the U(VI) species indicates the transition of a major U(VI) species by means of geothermal gradient and decay heat from the radioactive isotopes, representing the necessity of deeper consideration in the safety assessment of geologic repository.

Acknowledgement

Supported by : National Research Foundation of Korea (NRF)

References

  1. V. Moulin and G. Ouzqunian, Appl. Geochem., 7(1), pp. 179-186 (1992) https://doi.org/10.1016/S0883-2927(09)80074-7
  2. G. Meinrath, Y. Kato, and Z. Yoshida, J. Radioanal. Nucl. Chem., 174(2), pp. 299-314 (1993) https://doi.org/10.1007/BF02037917
  3. C. Moulin, I. Laszak, V. Moulin, and C. Tondre, Appl. Spectrosc., 52(4), pp. 528-535 (1998) https://doi.org/10.1366/0003702981944076
  4. W. Dong and S. C. Brooks, Environ. Sci. Technol., 40(15), pp. 4689-4695 (2006) https://doi.org/10.1021/es0606327
  5. G. Meinrath, J. Alloys Compd., 275-277, pp. 777-781 (1998) https://doi.org/10.1016/S0925-8388(98)00439-3
  6. I. Grenthe and B. Lagerman, Acta Chem. Scand., 45, pp. 122-128 (1991) https://doi.org/10.3891/acta.chem.scand.45-0122
  7. J. U. Lim, S. G. Lee, H. C. Kim, H. C. Lim, D. J. Bae, S. Y. Hamm, C. W. Lee, and K. S. Ahn, "Preliminary Study of the Geothermal Resource in the Muju area", KR-94(C)1-13, KIGAM (1995)
  8. P. Zanonato, P. D. Bernardo, A. Bismondo, G. Liu, X. Chen, and L. Rao, J. Am. Chem. Soc., 126(17), pp. 5515-5522 (2004) https://doi.org/10.1021/ja0398666
  9. H. C. Helgeson, J. Phys. Chem., 71(10), pp. 3121-3136 (1967) https://doi.org/10.1021/j100869a002
  10. I. Puigdomenech, J. A. Rard, A. V. Plyasunov, and I. Grenthe, Temperature Corrections to Thermodynamic Data and Enthalpy Calculations, OECD-NEA, Elsevier (1999)
  11. W. Stumm and J. J. Morgan, Aquatic Chemistry, John Wiley & Sons (1996)
  12. Y. Kato, G. Meinrath, T. Kimura, and Z. Yoshida, Radiochim. Acta, 64, pp. 107-111 (1994)
  13. V. Eliet, G. Bidoglio, N. Omenetto, L. Parma, and I. Grenthe, J. Chem. Soc., Faraday Trans., 91(15), pp. 2275-2285 (1995) https://doi.org/10.1039/ft9959102275
  14. V. Eliet, I. Grenthe, and G. Bidoglio, Appl. Spectrosc., 54(1), pp. 99-105 (2000) https://doi.org/10.1366/0003702001948178
  15. A. Kirishima, T. Kimura, O. Tochiyama, and Z. Yoshida, J. Alloys Compd., 374, pp. 277-285 (2004) https://doi.org/10.1016/j.jallcom.2003.11.105
  16. J. R. Lakowicz, Principles of Fluorescence Spectroscopy, Springer (2006)
  17. R. Guillaumont, T. Fanghanel, V. Neck, J. Fuger, D. A. Palmer, I. Grenthe, and M. H. Rand, Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium, OECD-NEA, Elsevier (2003)
  18. W. L. Marshall and E. U. Franck, J. Phys. Chem. Ref. Data, 10(2), pp. 295-304 (1981) https://doi.org/10.1063/1.555643
  19. L. Ciavatta, D. Ferri, M. Grimaldi, R. Palombari, and F. Salvatore, J. Inorg. Nucl. Chem, 41, pp. 1175-1182 (1979) https://doi.org/10.1016/0022-1902(79)80479-0
  20. I. Grenthe, H. Wanner, and E. Osthols, Guidelines for the Extrapolation to Zero Ionic Strength, OECD-NEA (2000)
  21. I. Grenthe, J. Fuger, R. J. M. Konings, R. J. Lemire, A. B. Muller, C. N.-T. Cregu, an d H. Wanner, Chemical Thermodynamics of Uranium, OECD-NEA, Elsevier (1992)