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Stability Constants of Np(V) Complexes with Phosphate at Variable Temperatures

Conference ·
OSTI ID:947952
A solvent extraction method was used to determine the stability constants of Np(V) complexes with phosphate in 1.0 M NaClO4 from 25o C to 55o C. A morpholine-4-ethanesulfonic acid buffer was used to maintain pH at about 5 in the Np(V)-H2PO4- system. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of phosphate were increased. Stability constants of the 1:1 Np(V)-H2PO4- complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [H2PO4-] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures by using the Van’t Hoff equation.
Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-76RL01830
OSTI ID:
947952
Report Number(s):
PNNL-SA-48528; DF0961000
Country of Publication:
United States
Language:
English

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