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[en] Kinetics of interaction of americium tri- and pentavalent ions in solutions of potassium tungstophosphates (KPW) depending on pH (0.2-5.0), KPW concentration and temperature is studied using spectrophotometric method. It is established that reaction of americium (4) reproportionation is the final result of the interaction. It proceeds according to stoichiometric equation Amsup((3))+Amsup((5))=2Amsup((4)) (1). At the same time, reaction of the first order as to actual concentration of americium (5) or americium (3) is the stage which determines the observed rate of Am (4) accumulation. It is shown that interaction of americium (3) and americium (5) depends on the sequence of reacting agents introduction and proceeds either according to (1) or by means pentavalent americium disproportionation with subsequent interaction of americium (6) and americium (3)

[en] The kinetics of interaction between tri- and pentavalent americium ions in the potassium phosphorotungstate solutions (KPW) depending on pH(0.2-5.0), KPW concentration and temperature have been studied by spectrophotometric method. It has been stated that the above interaction resulted in the americium (4) reproportion according to the stoichiometric equation, Am(3)+Am(5)=2Am(4). Yet, it has been found that the first order reaction relative to the current concentration of Am(5) or Am(3) is the stage which governs the observed rate for Am(4) build-up. It has been also demonstrated that Am(3) and Am(5) interaction depends upon the order of reactant insertion and it proceeds either just according to the above equation or through the disproportion of the pentavalent americium and then by interaction of Am(6) and Am(3)

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[en] The kinetics of the study of the reversible reaction Am/sup (VI)/ + Am/sup (III)/ ↔ Am/sup (V)/ + Am/sup (IV)/ in K₁₀P₂W₁₇O₆₁ solutions reaction has been studied spectroscopically at pH 0-6, K₁₀P₂W₁₇O₆₁ concentration 0.75-12 mM, and 16-35⁰C. It has been shown that this reaction follows the second-order reaction rate law -d[Am/sup (III)/]/dt = k/sub ef/[Am/sup (III)/] x [Am/sup (VI)/]. The rate constants of the forward and reverse reactions lie within 10³-10⁶ mole^-1 x liter x min^-1 and have a complicated relation with the acidity of the solution and the concentration of K₁₀P₂W₁₇O₆₁. The activation energy for the reaction between americium(III) and americium(VI) is 96 +/- 12 kJ/mole

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[en] Investigated was extraction of tri-valent curium, berkelium, californium, einsteinium as well as cerium and europium with trioctylphosphin oxide from lactic acid solutions, containing DTPA and aluminium nitrate depending on the aluminium nitrate and TOPO concentrations and nitric acid solutions of variable concentration as well. Under optimum conditions of extraction chromatography of berkelium studied was the distribution of cobalt, nickel, chromium, iron, aluminium, titanium, zirconium and niobium ions, and the coefficients of berkelium purification from cations investigated were determined. The effect of weight quantities of cation impurities on extraction chromatographic yield of berkelium has been investigated. Examples of practice application of the extraction chromatography with the use of TOPO are given

[en] Spectrophotometric method is used to investigate americium (6) behaviour in solutions of potassium phosphotungstate (KPW) at different pH values, americium concentration and KPW. It is shown that under studied experimental conditions americium (6) migrates only into americium (4). Reduction of americium (6) in KPW solutions is stated to be the result of radiation-chemical interactions. An equation of the law of Am(6) reduction rate is presented. Basing on the obtained experimental data a scheme of americium (6) reduction including a series of redox reactions with americium ion participation is suggested

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No abstract available