Thermodynamics of Neptunium (V) Complexes with Phosphate at Elevated Temperatures

Journal Article · Mon Jun 01 04:00:00 EDT 2009 · Journal of Radioanalytical and Nuclear Chemistry, 280(3):599-605

DOI:https://doi.org/10.1007/s10967-009-7476-8· OSTI ID:963196

Xia, Y; Friese, Judah I; Bachelor, Paula P; Moore, Dean A; Rao, Linfeng

Abstract – The complexation of Np(V) with phosphate at elevated temperatures was studied by a synergistic extraction method. A mixed buffer solution of TRIS and MES was used to maintain an appropriate pH value during the distribution experiments. 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 and 1:2 Np(V)-HPO42- complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [HPO42-] on the distribution ratio. The thermodynamic parameters including enthalpy and entropy of complexation between Np(V) and HPO42- at 25o C – 55o C were calculated by the temperature coefficient method.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 963196
• Report Number(s): PNNL-SA-64554; NN2001000
• Journal Information: Journal of Radioanalytical and Nuclear Chemistry, 280(3):599-605, Journal Name: Journal of Radioanalytical and Nuclear Chemistry, 280(3):599-605 Journal Issue: 3 Vol. 280; ISSN JRNCDM; ISSN 0236-5731
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ENTHALPY
ENTROPY
NEPTUNIUM COMPOUNDS
PHOSPHATES
STABILITY
TEMPERATURE COEFFICIENT
THERMODYNAMICS
pentavalent neptunium
complexation
phosphate
elevated temperatures