skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Complexation of Uranium(VI) with Thiodiacetic Acid in Solution at10 - 85oC

Abstract

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.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - U. diPadova/Italy
OSTI Identifier:
918820
Report Number(s):
LBNL-61629
Journal ID: ISSN 1434-1948; EJICFO; R&D Project: 403006; BnR: KC0302030; TRN: US0805911
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: European Journal of Inorganic Chemistry; Journal Volume: 0; Related Information: Journal Publication Date: 2006
Country of Publication:
United States
Language:
English
Subject:
37; CALORIMETRY; ELECTROSTATICS; ENTHALPY; POTENTIOMETRY; SOLVENTS; SPECIFIC HEAT; THERMODYNAMICS; URANIUM

Citation Formats

Di Bernardo, Plinio, Zanonato, PierLuigi, Bismondo, Arturo, Jiang, Huijian, Garnov, Alexander Yu., Jiang, Jun, and Rao, Linfeng. Complexation of Uranium(VI) with Thiodiacetic Acid in Solution at10 - 85oC. United States: N. p., 2006. Web.
Di Bernardo, Plinio, Zanonato, PierLuigi, Bismondo, Arturo, Jiang, Huijian, Garnov, Alexander Yu., Jiang, Jun, & Rao, Linfeng. Complexation of Uranium(VI) with Thiodiacetic Acid in Solution at10 - 85oC. United States.
Di Bernardo, Plinio, Zanonato, PierLuigi, Bismondo, Arturo, Jiang, Huijian, Garnov, Alexander Yu., Jiang, Jun, and Rao, Linfeng. Sun . "Complexation of Uranium(VI) with Thiodiacetic Acid in Solution at10 - 85oC". United States. doi:.
@article{osti_918820,
title = {Complexation of Uranium(VI) with Thiodiacetic Acid in Solution at10 - 85oC},
author = {Di Bernardo, Plinio and Zanonato, PierLuigi and Bismondo, Arturo and Jiang, Huijian and Garnov, Alexander Yu. and Jiang, Jun and Rao, Linfeng},
abstractNote = {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.},
doi = {},
journal = {European Journal of Inorganic Chemistry},
number = ,
volume = 0,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • No abstract prepared.
  • The protonation reactions of oxalate (ox) and the complex formation of uranium(VI) with oxalate in 1.05 mol kg{sup -1} NaClO{sub 4} were studied at variable temperatures (10-70 C). Three U(VI)/ox complexes (UO{sub 2}ox{sub j}{sup (2-2j){sup +}} with j = 1, 2, 3) were identified in this temperature range. The formation constants and the molar enthalpies of complexation were determined by spectrophotometry and calorimetry. The complexation of uranium(VI) with oxalate ion is exothermic at lower temperatures (10-40 C) and becomes endothermic at higher temperatures (55-70 C). In spite of this, the free energy of complexation becomes more negative at higher temperaturesmore » due to increasingly more positive entropy of complexation that exceeds the increase of the enthalpy of complexation. The thermodynamic parameters at different temperatures, in conjunction with the literature data for other dicarboxylic acids, provide insight into the relative strength of U(VI) complexes with a series of dicarboxylic acids (oxalic, malonic and oxydiacetic) and rationalization for the highest stability of U(VI)/oxalate complexes in the series. The data reported in this study are of importance in predicting the migration of uranium(VI) in geological environments in the case of failure of the engineering barriers which protect waste repositories.« less
  • The complexation of uranium(VI) and samarium(III) with oxydiacetate in 1.05 mol kg{sup -1} NaClO{sub 4} is studied at variable temperatures (25-70 C). Three U(VI)/O DA complexes (UO{sub 2}L, UO{sub 2}L{sub 2}{sup 2-}, and UO{sub 2}HL{sub 2}{sup -}) and three Sm(III)/ODA complexes (SmL{sub j}{sup (3-2j)+} with j = 1, 2, 3) are identified in this temperature range. The formation constants and the molar enthalpies of complexation are determined by potentiometry and calorimetry. The complexation of uranium(VI) and samarium(III) with oxydiacetate becomes more endothermic at higher temperatures. However, the complexes become stronger due to increasingly more positive entropy of complexation at highermore » temperatures that exceeds the increase in the enthalpy of complexation. The values of the heat capacity of complexation ({Delta}C{sub p}{sup o} in J K{sup -1} mol{sup -1}) are 95 {+-} 6, 297 {+-} 14, and 162 {+-} 19 for UO{sub 2}L, UO{sub 2}L{sub 2}{sup 2-}, and UO{sub 2}HL{sub 2}{sup -}, and 142 {+-} 6, 198 {+-} 14 and 157 {+-} 19 for SmL{sup +}, SmL{sub 2}{sup -}, and SmL{sub 3}{sup 3-}, respectively. The thermodynamic parameters, in conjunction with the structural information from spectroscopy, help to identify the coordination modes in the uranium oxydiacetate complexes. 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.« less