Redox Behavior of Am(IV) and Methods of Its Preparation in Alkaline Media |
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| Authors: | M V Nikonov A V Gogolev I G Tananaev B F Myasoedov D L Clark |
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| Affiliation: | (1) Institute of Physical Chemistry, Russian Academy of Sciences, Moscow, Russia;(2) Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, Russia;(3) Seaborg Institute, Los Alamos National Laboratory, USA |
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| Abstract: | A scheme was suggested for Am(OH)4 isolation by treatment of Am(OH)3 suspension in 0.1–1.0 M NaOH with ozone (3.5–5 vol %)-oxygen mixture (4–5 l h−1 flow rate) at 20°C for 40 min, followed by ultrasonic treatment of the resulting Am(VI) (44 kHz, 1 W cm−3) for 45 min. The separated precipitate of Am(III) hydroxy peroxide was treated with 1–2 mlof 7–10 M NaOH to form Am(OH)4. Mixing suspensions of equivalent amounts of Am(III) and Am(V) hydroxides in NaOH also gives Am(IV) hydroxide in a >98% yield. The reproportionation Am(III) + Am(V) = 2Am(IV) in 1 M NaOH starts on heating above 70°C, whereas at NaOH concentration higher than 7 M it is completed even at room temperature. The reaction of Am(III) with Am(VI) in alkaline solutions, Am(VI) + 2Am(III) → 3Am(IV), occurs during mixing the reactants. The equilibrium reaction of Am(OH)3 with Fe(CN)6]3− in alkaline solutions was studied. It was shown that increasing the alkali concentration to 2 M NaOH promotes formation of Am(OH)4. At further increase in the alkali concentration, Am(V) is formed.__________Translated from Radiokhimiya, Vol. 47, No. 3, 2005, pp. 234–238.Original Russian Text Copyright © 2005 by Nikonov, Gogolev, Tananaev, Myasoedov, Clark. |
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