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Complexation of Gluconate with Uranium(VI) in Acidic Solutions: Thermodynamic Study with Structural Analysis

Description: Within the pC{sub H} range of 2.5 to 4.2, gluconate forms three uranyl complexes UO{sub 2}(GH{sub 4}){sup +}, UO{sub 2}(GH{sub 3})(aq), and UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -}, through the following reactions: (1) UO{sub 2}{sup 2+} + GH{sub 4}{sup -} = UO{sub 2}(GH{sub 4}){sup +}, (2) UO{sub 2}{sup 2+} + GH{sub 4}{sup -} = UO{sub 2}(GH{sub 3})(aq) + H{sup +}, and (3) UO{sub 2}{sup 2+} + 2GH{sub 4}{sup -} = UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -} + H{sup +}. Complexes were inferred from potent… more
Date: January 5, 2009
Creator: Zhang, Zhicheng; Helms, G.; Clark, S. B.; Tian, Guoxin; Zanonato, PierLuigi & Rao, Linfeng
Partner: UNT Libraries Government Documents Department
open access

Spectrophotometric and Calorimetric Studies of Np(V) Complexation with Acetate at Variable Temperatures (T = 283 - 343 K)

Description: Spectrophotometric titrations were performed to identify the Np(V)/acetate complex and determine the equilibrium constants at variable temperatures (T = 283 - 343 K) and at the ionic strength of 1.05 mol {center_dot} kg{sup -1}. The enthalpy of complexation at corresponding temperatures was determined by microcalorimetric titrations. Results show that the complexation of Np(V) with acetate is weak but strengthened as the temperature is increased. The complexation is endothermic and is entropy-d… more
Date: December 21, 2009
Creator: Rao, Linfeng; Tian, Guoxin; Srinivasan, Thandankorai G.; Zanonato, PierLuigi & Di Bernardo, Plinio
Partner: UNT Libraries Government Documents Department
open access

Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation

Description: Recent results of thermodynamic studies on the complexation of actinides (UO{sub 2}{sup 2+}, NpO{sub 2}{sup +} and Pu{sup 4+}) with F{sup -}, SO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}/HPO{sub 4}{sup 2-} at elevated temperatures are reviewed. The data indicate that, for all systems except the 1:1 complexation of Np(V) with HPO{sub 4}{sup 2-}, the complexation of actinides is enhanced by the increase in temperature. The enhancement is primarily due to the increase in the entropy term (T{Delt… more
Date: December 21, 2009
Creator: Rao, Linfeng; Tian, Guoxin; Xia, Yuanxian; Friese, Judah I.; Zanonato, PierLuigi & Di Bernardo, Plinio
Partner: UNT Libraries Government Documents Department
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