Title: Investigation of the Hydrolysis of Plutonium(IV) by a Combination of Spectroscopy and Redox Potential Measurements
Authors: YUN J.-I.CHO H. R.NECK V.ALTMAIER M.SEIBERT AliceMARQUARDT C. M.WALTHER C.FANGHAENEL THOMAS
Citation: RADIOCHIMICA ACTA vol. 95 p. 89-95
Publisher: OLDENBOURG VERLAG
Publication Year: 2007
JRC N°: JRC42506
ISSN: 0033-8230
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC42506
DOI: 10.1524/ract.2007.95.2.89
Type: Articles in Journals
Abstract: The hydrolysis of tetravalent plutonium in 0.5M HCl/NaCl has been investigated by a combination of spectroscopy and redox potential measurements in the concentration range from 10-5 to 4×10-4 M and at pHc 0.3¿2.1. Redox potentials were both measured and calculated from the plutonium oxidation state distributions using well-known equilibrium constants for the redox reactions of plutonium. The plutonium oxidation states in solution were quantified by spectroscopy. The pe values calculated from the plutonium redox couples Pu(V)/Pu(VI) and PuO2(am,hyd)/Pu(V) were found to be consistent with the measured pe values whereas those calculated from the Pu(III)/Pu(IV) couple were found to deviate, suggesting that the formation constants selected in recent reviews for the mononuclear hydroxide complexes of Pu(IV) are overestimated. Combining the redox potentials and the spectroscopically determined Pu(III) and Pu(IV) concentrations, the formation constants of the first, second, and third mononuclear hydroxide complexes Pu(OH)n 4-n at I = 0.5M and 23±2 ¿C are calculated and corrected to zero ionic strength using the specific ion interaction theory (SIT): log ß¿11 = 14.0±0.2, log ß¿12 = 26.8±0.6, and log ß¿13 = 38.9±0.9.
JRC Institute:Institute for Transuranium Elements

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