Electrochemical oxidation of 243 Am(III) in nitric acid by a terpyridyl-derivatized electrode

High fives and sixes for Americium ions You've probably heard of uranium and plutonium. Americium (Am) is less widely discussed outside chemistry circles, but the separation of this heavier radioactive element from nuclear waste streams is a major goal of fuel reprocessing research. The trouble...

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Published in:Science (American Association for the Advancement of Science) 2015-11, Vol.350 (6261), p.652-655
Main Authors: Dares, Christopher J., Lapides, Alexander M., Mincher, Bruce J., Meyer, Thomas J.
Format: Article
Language:English
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Summary:High fives and sixes for Americium ions You've probably heard of uranium and plutonium. Americium (Am) is less widely discussed outside chemistry circles, but the separation of this heavier radioactive element from nuclear waste streams is a major goal of fuel reprocessing research. The trouble is that trivalent Am ions are hard to tease apart from similarly charged lanthanide ions. Dares et al. now show that terpyridyl ligands appended to an electrode can promote the oxidation of trivalent Am ions to the pentavalent and hexavalent states (see the Perspective by Soderquist). These more highly charged ions should be easier to isolate for the subsequent use of the Am in next-generation nuclear reactors. Science , this issue p. 652 ; see also p. 635 Ligands on an electrode promote oxidation of americium ions, raising prospects for their isolation from nuclear waste streams. [Also see Perspective by Soderquist ] Selective oxidation of trivalent americium (Am) could facilitate its separation from lanthanides in nuclear waste streams. Here, we report the application of a high-surface-area, tin-doped indium oxide electrode surface-derivatized with a terpyridine ligand to the oxidation of Am(III) to Am(V) and Am(VI) in nitric acid. Potentials as low as 1.8 volts (V) versus the saturated calomel electrode were applied, 0.7 V lower than the 2.6 V potential for one-electron oxidation of Am(III) to Am(IV) in 1 molar acid. This simple electrochemical procedure provides a method to access the higher oxidation states of Am in noncomplexing media for the study of the associated coordination chemistry and, more important, for more efficient separation protocols.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aac9217