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Licensed Unlicensed Requires Authentication Published by De Gruyter (O) October 15, 2012

Spectroscopic study of Pu(IV) oxidation to Pu(VI) in 3 mol/dm3 nitric acid at 373 K

  • Yasutoshi Ban and Yasuji Morita
From the journal Radiochimica Acta

Abstract

Optical absorption spectra of Pu(IV) in 3 mol/dm3 (M) nitric acid at 373 K were measured using an optical quartz cell equipped with a thin-film heater. Pu(IV) was oxidized to Pu(VI) by heating at 373 K, and the concentrations of Pu(IV) and Pu(VI) gradually decreased and increased, respectively, with the heating time. The ratio of Pu(IV) oxidized to Pu(VI) was 37% at a heating time of 394 min, and no Pu(III) or Pu(V) characteristic peaks were observed throughout the experiment. The oxidation rate of Pu(IV) in 3 M nitric acid at 373 K could be described by the equation -d [Pu(IV)]t/d t= k′1 [Pu(IV)]t-k′2 [Pu(VI)]t, where [Pu(IV)]t and [Pu(VI)]t were the concentrations of Pu(IV) and Pu(VI) at a heating time of t min. The apparent rate constants for Pu(IV) oxidation (k′1) and Pu(VI) reduction (k′2) at 373 K were calculated to be 2.3 × 103 min-1 and 3.4 × 103 min-1, respectively.


* Correspondence address: Japan Atomic Energy Agency, Research Group for Aqueous Separation Process Chem, Shirane 2-4, Nuclear Science and Engineering Directorate, 319-1195 Tokai, Ibaraki, Japan,

Published Online: 2012-10-15
Published in Print: 2012-12

© by Oldenbourg Wissenschaftsverlag, München, Germany

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