Thermodynamics of actinide hydrolysis
- Florida State Univ., Tallahassee, FL (United States)
Thermodynamic parameters of Np(V), U(VI), and Pu(VI) hydrolysis have been measured at 5-45{degrees}C via calorimetric titration. These parameters are needed to evaluate actinide migration behavior in the near field of nuclear waste repositories which are expected to reach temperatures of 100{degrees}C. The enthalpies determined exhibit both a temperature as well as an ionic media dependence. Calorimetry provides a direct, quantitative method to observe the energetic consequences of hydrolysis and the solute-solvent interactions between actinide metals and their coordination spheres in aqueous solution. The different enthalpies of hydrolysis in 1M Me{sub 4}NCl and NaClO{sub 4} provide further insight concerning their second sphere salvation structures. Our results suggest {Delta}Cp is linear over the 40{degrees} temperature range. The linear correlation between {Delta}{Delta}H and {Delta}Cp reflects the dominance of solvent reorganization in the {Delta}Cp term. Based on our values of {Delta}Cp for Np(V), U(VI), and Pu(VI) hydrolysis, the Van`t Hoff equation (assumes {Delta}Cp=O) may not be used to estimate hydrolysis constants at elevated temperatures.
- OSTI ID:
- 370664
- Report Number(s):
- CONF-960376-; TRN: 96:003805-0722
- Resource Relation:
- Conference: Spring national meeting of the American Chemical Society (ACS), New Orleans, LA (United States), 24-28 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 211th ACS national meeting; PB: 2284 p.
- Country of Publication:
- United States
- Language:
- English
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