Solubility of plutonium in MgCl2 and CaCl2 solutions in contact with metallic iron
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Publication Details
Output type: Other
Author list: Altmaier M, Neck V, Lutzenkirchen J, Fanghaenel T
Publisher: De Gruyter
Publication year: 2009
Volume number: 97
Issue number: 4-5
Start page: 187
End page: 192
Number of pages: 6
ISSN: 0033-8230
eISSN: 2193-3405
Languages: English-Great Britain (EN-GB)
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Open access status: closed
Abstract
The solubility of Pu(IV) hydrous oxide is studied at 22 +/- 2 degrees C under Ar atmosphere in 0.25 and 3.5 M MgCl2 (pH(c) approximate to 9) and 3.5 M CaCl2 (pH(c) = 11-12) solutions in contact with iron powder. In alkaline 3.5-4.0 M CaCl2 ternary Ca-Pu-OH complexes are formed and the solubility of PuO2 center dot xH(2)O(s) increases from about 10(-10) M at pH(c) = 11 to 10(-8)-10(-7) M at pH(c) = 12, both in the presence and absence of Fe powder. In the presence of iron the aqueous speciation is dominated by Pu(III) at pH(c) < 10 and by Pu(IV) complexes at pH(c) > 10. In the absence of reducing agents the aqueous speciation is dominated by Pu(V), with significant contributions of Pu(IV) complexes at pH(c) > 10. The effect of ternary Ca-Pu(III,IV,V)-OH complexes in alkaline CaCl2 solutions can be described by assuming complex stoichiometries and experimental data from the oxidation state analogs Cm(III)/Nd(III), Th(IV) and Np(V). The ion interaction Pitzer approach is used for model calculations.
Keywords
Iron, Pitzer model, Plutonium, Redox control, Solubility, Ternary Ca-Pu-OH complexes
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