Complexation of Uranium(VI) with Thiodiacetic Acid in Solution at 10–85 °C

Autor: Jun Jiang, Alexander Yu. Garnov, Linfeng Rao, Arturo Bismondo, Plinio Di Bernardo, Huijian Jiang, Pier Luigi Zanonato
Rok vydání: 2006
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2006:4533-4540
ISSN: 1099-0682
1434-1948
DOI: 10.1002/ejic.200600554
Popis: The protonation of thiodiacetate and its complexation with uranium(VI) in 1.05 molkg{sup -1} NaClO{sub 4} are studied at variable temperatures (10-85 C). Three UVI complexes (UO{sub 2}L, UO{sub 2}HL{sup +}, and UO{sub 2}HL{sup 2-}, where L is thiodiacetate) are identified in this temperature range. The formation constants and the enthalpies of complexation are determined by potentiometry and calorimetry. The complexation of uranium(VI) with thiodiacetate becomes more endothermic at higher temperatures. However, the complexes become stronger due to increasingly more positive entropies of complexation at higher temperatures, which exceeds the increase in the unfavorable enthalpy of complexation. The values of the heat capacity of complexation ({Delta}Cp) are 122{+-}16, 302{+-}26, and 242{+-}23 JK{sup -1} mol{sup -1} for UO{sub 2}L, UO{sub 2}HL{sup +}, and UO{sub 2}HL{sup 2-}, respectively. The effect of temperature on the thermodynamics of the complexation is discussed in terms of the electrostatic model and the change in the solvent structure.
Databáze: OpenAIRE
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