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Title: Oxidation of Uranium(IV) with Oxygen in NaHCO3 Solution

Abstract

The kinetics of uranium(IV) oxidation by atmospheric oxygen in NaHCO3 solutions has been studied by sampling and analysis. In 1 M NaHCO3 solution with an initial 20 mM U(IV) concentration, an induction period is observed; the induction period is almost absent at an initial (U(IV) concentration of 1.0 mM. The induction period is related to the U(IV) that initially is present as poorly reactive polymer species. Introduction of U(VI) to the initial solution accelerates oxidation. In 1 M NaHCO3 solution containing 0.1 to 1.0 M U(IV), the rate of U(IV) decrease obeys first-order rate law relative U(IV) and O2 concentrations. The pseudo first-order and bimolecular rate constants and the activation energy of U(IV) oxidation by O2 have been determined. Hydrolysis and polymerization of U(IV) have been shown to increase as NaHCO3 concentration decreases from 0.5 to 0.01 M. Based on the experimental results, the reaction is shown to be autocatalytic and proceeds through formation of a [U(IV)•U(VI)] complex with which O2 reacts faster than with U(IV). Uranium(IV) oxidation proceeds through a two-electron charge transfer mechanism.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
946652
Report Number(s):
PNNL-SA-55628
Journal ID: ISSN 0033-8311; RADKAU; TRN: US0900947
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Radiokhimiya, 50(5):397-402
Additional Journal Information:
Journal Volume: 50; Journal Issue: 5; Journal ID: ISSN 0033-8311
Country of Publication:
United States
Language:
English
Subject:
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; URANIUM; OXIDATION; SODIUM CARBONATES; CHEMICAL REACTION KINETICS; ELECTRON TRANSFER; URANIUM COMPLEXES

Citation Formats

Shilov, V P, Yusov, A B, Fedoseev, A M, Peretrukhin, V F, and Delegard, Calvin H. Oxidation of Uranium(IV) with Oxygen in NaHCO3 Solution. United States: N. p., 2008. Web. doi:10.1134/S1066362208050044.
Shilov, V P, Yusov, A B, Fedoseev, A M, Peretrukhin, V F, & Delegard, Calvin H. Oxidation of Uranium(IV) with Oxygen in NaHCO3 Solution. United States. https://doi.org/10.1134/S1066362208050044
Shilov, V P, Yusov, A B, Fedoseev, A M, Peretrukhin, V F, and Delegard, Calvin H. 2008. "Oxidation of Uranium(IV) with Oxygen in NaHCO3 Solution". United States. https://doi.org/10.1134/S1066362208050044.
@article{osti_946652,
title = {Oxidation of Uranium(IV) with Oxygen in NaHCO3 Solution},
author = {Shilov, V P and Yusov, A B and Fedoseev, A M and Peretrukhin, V F and Delegard, Calvin H},
abstractNote = {The kinetics of uranium(IV) oxidation by atmospheric oxygen in NaHCO3 solutions has been studied by sampling and analysis. In 1 M NaHCO3 solution with an initial 20 mM U(IV) concentration, an induction period is observed; the induction period is almost absent at an initial (U(IV) concentration of 1.0 mM. The induction period is related to the U(IV) that initially is present as poorly reactive polymer species. Introduction of U(VI) to the initial solution accelerates oxidation. In 1 M NaHCO3 solution containing 0.1 to 1.0 M U(IV), the rate of U(IV) decrease obeys first-order rate law relative U(IV) and O2 concentrations. The pseudo first-order and bimolecular rate constants and the activation energy of U(IV) oxidation by O2 have been determined. Hydrolysis and polymerization of U(IV) have been shown to increase as NaHCO3 concentration decreases from 0.5 to 0.01 M. Based on the experimental results, the reaction is shown to be autocatalytic and proceeds through formation of a [U(IV)•U(VI)] complex with which O2 reacts faster than with U(IV). Uranium(IV) oxidation proceeds through a two-electron charge transfer mechanism.},
doi = {10.1134/S1066362208050044},
url = {https://www.osti.gov/biblio/946652}, journal = {Radiokhimiya, 50(5):397-402},
issn = {0033-8311},
number = 5,
volume = 50,
place = {United States},
year = {Wed Oct 01 00:00:00 EDT 2008},
month = {Wed Oct 01 00:00:00 EDT 2008}
}