Heterogeneous reduction of 239PuO2 by aqueous Fe(II) in the presence of hematite
The reduction of PuO (am) by Fe(II) in the presence and absence of hematite was studied over a range of pH values and oxidation/reduction potentials. In contrast to thermodynamic predictions, the presence of hematite did not have a major effect on the overall reduction of PuO (am) to aqueous Pu(III)...
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Published in | Radiochimica acta Vol. 101; no. 11; pp. 701 - 710 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
De Gruyter
01.11.2013
|
Subjects | |
Online Access | Get full text |
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Summary: | The reduction of PuO
(am) by Fe(II) in the presence and absence of hematite was studied over a range of pH values and
oxidation/reduction potentials. In contrast to thermodynamic predictions, the presence of hematite did not have a major
effect on the overall reduction of PuO
(am) to aqueous Pu(III). Instead the aqueous Pu(III) concentrations at longer time
frames were accurately predicted using the measured Fe(II) concentration and existing thermodynamic data for the reaction:
H
O + H
+ Fe
+ PuO
(am) ⇌ Pu
+ Fe(OH)
(am)
with log
=− 0.6. The accuracy of this approach in all solutions containing aqueous Fe(II), coupled with the apparent lack
of oxidation of Fe(II) by O
(g), suggests that the Fe(OH)
(am) is formed by the oxidation of Fe(II) to Fe(III) by
radiolysis. The continued generation of reactive amorphous iron hydroxide by radiolysis prevents thermodynamic equilibrium from
being reached with more stable ferric oxide compounds, except possibly under acidic conditions where amorphous ferric hydroxide
is soluble. The use of measured pe values, instead of aqueous Fe(II) measurements, also yields reasonable predictions of the
final Pu(III) concentrations although the predictions are more uncertain. |
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Bibliography: | USDOE Office of Science (SC), Biological and Environmental Research (BER) |
ISSN: | 0033-8230 2193-3405 |
DOI: | 10.1524/ract.2013.2091 |