Reductive Dissolution of PuO2(am): The Effect of Fe(II) and Hydroquinone |
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Authors: | Dhanpat Rai Yuri A Gorby Jim K Fredrickson Dean A Moore Mikazu Yui |
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Institution: | (1) Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MISNP 7-50 Richland, Washington;(2) Japan Nuclear Cycle Development Institute, Tokai Works, Japan |
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Abstract: | PuO2(am) solubility was investigated as a function of time, for pH from 0.5 to 11, and in the presence of 0.001 M FeCl2 or 0.00052 M hydroquinone to determine the effect of environmentally important reducing agents on PuO2(am) solubilization under geological conditions. Equilibrium was reached in <4 days. The observed PuO2(am) solubilities were many orders of magnitude higher than the Pu(IV) concentrations predicted from thermodynamic data. Spectroscopic, solvent extraction, and thermodynamic analyses of data showed that Pu(III) was the dominant aqueous oxidation state. The experimental pH, pe, and Pu(III) concentrations from both the Fe(II) and hydroquinone systems provided a log K
0 value of 15.5 ± 0.7 for PuO2(am) + 4H+ + e
– Pu3+ + 2H2O]. The data show that reduction reactions involving Fe(II) and hydroquinone are relatively rapid and that reductive dissolution of PuO2(am), hitherto ignored, may play an important role in controlling Pu behavior under reducing environmental conditions. |
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Keywords: | Solubility solubility product PuO2(am) Pu(III) Pu(IV) redox reactions thermodynamics ion– interaction parameters |
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