The oxidation of uranium(IV) ions by nitrous acid in 30% tri-butyl phosphate
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V. S. Koltunov
Summary
The kinetics of the oxidation of U(IV) ions by nitrous acid in a 30% TBP solution have been determined. The rate equation was found to be:
-d[U(IV)]/dt = k2a([U(IV)][HNO2][HNO3][H2O])/([HNO3]2+β3[HNO3][H2O]+β4[H2O]2),
where, k2a=0.405±0.055 M-1 min-1 at 55 °C (β3≈0.08; β4≈0.007) and the activation energy was E=112±17 kJ mol-1. The reaction mechanism appeared to involve interaction with the 1st hydrolysis product of U(IV)–UOH3+. The data is compared with a previous study of the nitric acid oxidation of U(IV) in 30% TBP. This reaction is autocatalytic due to the formation of nitrous acid during the reaction. The kinetics of the decomposition of HNO2 in 30% TBP (in the absence of U(IV)) have also been reported.
© 2004 Oldenbourg Wissenschaftsverlag GmbH
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Articles in the same Issue
- On-line anion exchange of rutherfordium in HF/HNO3 and HF solutions
- The oxidation of uranium(IV) ions by nitrous acid in 30% tri-butyl phosphate
- Anion-exchange behavior of Mo and W as homologs of Sg (element 106) in HCl and HNO3 as well as in mixed HCl-HF and HNO3-HF solutions
- Crystal structures of Np(VI) and Pu(VI) phthalates, [NpO2{(OOC)2C6H4}H2O]·1/3H2O and [PuO2{(OOC)2C6H4}H2O]·H2O
- TRLIFS study of Eu(III) spectroscopic properties to obtain structural and thermodynamic informations on lanthanide-malonamide complexes in the Eu(III)/NaNO3/TetraEthylMalonAmide system
- Sorption of fission product radionuclides, 137Cs and 90Sr, by Savannah River Site sediments impregnated with colloidal silica
- Removal of silver and antimony radionuclides from low-level liquid radioactive waste of a research reactor through different scavenging precipitations
- Determination of trace element concentration in infant head hair of Rawalpindi/Islamabad area using INAA technique
- Fluorescence spectroscopy on protactinium(IV) in aqueous solution
