Kinetic americium oxidation

T. W. Newton, The Kinetics of Oxidation-Reduction Reactions of Uranium, Neptunium, Plutonium, and Americium in Aqueous Solutions , ERDA Technical Information Center, Oak Ridge, Tenn., U.S.A., 1975. 

In conclusion, we can state that additions of small amounts of phosphoric acid increase the rate of Am (III) oxidation by Ag + ions without drastically changing the distribution coefficients of the species involved, because no complexation of Am occurs in these solutions, contrary to what occured in the extensive studies of Myassoeodov et al. (12, 13) in more concentrated phosphoric acid, where the kinetic effects must be attributed to changes in americium and silver (II) ionic species. In our Am-Cm separations we added phosphoric acid, which accelerates the oxidation rates of Am (III), solubilizes argentic oxide, and makes it possible to obtain Am (VI) quantitatively and rapidly at room temperature. 

Actinides.— A kinetic study has been made of the reduction of neptunium(vn) and americium(vi) by bromide ion. In both cases two moles of oxidant are consumed in the production of a mole of Brj. The rate law governing the neptunium(vii) reduction is of the form... 

Species (e.g. hydrogen peroxide and HO2 radicals) produced by radiolysis of water by alpha particles reduce the higher oxidation states of americium to Am(iii). Because of its lower specific addvity, the rates of autoreduction of Am species are much less than those of Am species. Zaitsev et at. [2S9] account for the kinetics of autoreduction of aqueous AmOl and AmO ions by assuming that H2O2 is consumed only in reducing Am(vi), Am(v) is reduced only by HO2 radicals, but Am(v) may be oxidized to Am(vi) by OH radicals. 

Extensive treatments of oxidation-reduction kinetics of the aqueous ions of uranium through americium are found in Chapters 5-8, in the critical monograph of Newton [264], and in a recent review [273]. 

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