Publications (7)1.64 Total impact
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Article: Disproportionation of Pu(V) in K10P2W17O61 solutions
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ABSTRACT: In solutions of unsaturated heteropolytungstate K10P2W17O61, Pu(V) disproportionates in a wide pH range; it is a first-order reaction with respect to Pu(V), and its rate only slightly changes in the pH range from 0.7 to 4.0. The activation energy E a of Pu(V) disproportionation was determined as 78.6±2.0 and 64.2±3 kJ mol−1 at pH 2.0±0.1 and 4.0±0.2, respectively. The thermodynamic parameters of activation ΔH ≠ and ΔS ≠ were evaluated. Published data on disproportionation of Np(V) and Am(V) in K10P2W17O61 solutions were analyzed.Radiochemistry 01/2007; 49(1):14-19. -
Article: Study of the NpO
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ABSTRACT: A new neptunium(VI) complex [(NpO2)(CrO4)(H2O)] ⋅ 4H2O (I) was synthesized, its crystal structure was determined, and the IR and near-IR absorption spectra were measured. The unit cell parameters are: a = 8.634(4) Å, b = 11.119(4) Å, c = 9.410(3) Å, β = 92.40(3)°, space group P21/c, Z = 4, V = 902.6(6) Å3, R = 0.048, wR(F 2) = 0.054. The crystal structure of the compound is composed of the [(NpO2)(CrO4)(H2O)] n layers and the crystal water molecules located between the layers. The coordination polyhedron of neptunium is a pentagonal bipyramid whose equatorial plane is formed by the oxygen atoms of two bridging water molecules and three chromate ions. The Np(VI) complexation with the chromate ions in an aqueous solution at μ = 1 was studied by spectrophotometry. The stability constants for 1 : 1 and 1 : 2 complexes were calculated, logβ1 = 3.19(2), logβ2 = 3.93(2), respectively.Russian Journal of Coordination Chemistry 01/2005; 31(11):804-808. · 0.55 Impact Factor -
Article: Interaction of Aluminium (III) with the f-Family Ions Np(VI), Pu(VI), Np(V), Np(IV), Pu(IV), Nd(III), and Am(III) in the Course of Simultaneous Hydrolysis
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ABSTRACT: The interaction of Np(VI), Pu(VI), Np(V), Np(IV), Pu(IV), Nd(III), and Am(III) with Al(III) in solutions at pH 0–4 was studied by the spectrophotometric method. It was shown that, in the range of pH 3–4, the hydrolyzed forms of neptunyl and plutonyl react with the hydrolyzed forms of aluminium. In the case of Pu(VI), the mixed hydroxoaqua complexes (H2O)3PuO2(-OH)2Al(OH)(H2O)3 2+ or (H2O)4PuO2OAl(OH)(H2O)4 2+ are formed at the first stage of hydrolysis. Np(VI) also forms similar hydroxoaqua complexes with Al(III). The formation of the mixed hydroxoaqua complexes was also observed when Np(IV) or Pu(IV) was simultaneously hydrolyzed with Al(III) at pH 1.5–2.5. The Np(IV) complex with Al(III) has, most likely, the formula (H2O) n (OH)Np(-OH)2Al(OH)(H2O)3 3+. At pH from 2 to 4.1 (when aluminium hydroxide precipitates), the Np(V) or Nd(III) ions exist in solutions with or without Al(III) in similar forms. When pH is increased to 5–5.5, these ions are almost not captured by the aluminium hydroxide precipitate.Russian Journal of Coordination Chemistry 03/2002; 28(4):264-271. · 0.55 Impact Factor -
Article: Interaction of Aluminium(III) with Uranyl Ions in the Course of Joint Hydrolysis
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ABSTRACT: Interaction of U(VI) with Al(III) in solutions at pH 2 and in precipitates obtained at pH 5 was studied using spectrophotometry, luminescence, and IR spectroscopy. It was shown that in the range of pH 3–4, hydrolyzed forms of uranyl and of aluminium come into interaction. The mixed hydroxoaqua complexes (H2O)3UO2(-OH)2Al(H2O)3+ 4,(H2O)3UO2(-OH)2Al(OH)(H2O)2+ 3, or (H2O)4UO2OAl(OH)(H2O)2+ 4are likely to form in the solution. With an increase in pH, mixed polymers of a large size (oligomers) can form which further take part in the precipitate formation. The reaction between U(VI) and Al(III) in precipitates is confirmed by the data of IR spectroscopy and by the changes in the physico-chemical properties of these precipitates as compared with the properties of a mechanical mixture of separately precipitated uranium and aluminium. The important role of the oligomeric mixed forms in the formation of precipitate remains at pH levels varying from 5 to 14.Russian Journal of Coordination Chemistry 10/2001; 27(11):776-782. · 0.55 Impact Factor -
Article: Plutonium(IV) precipitates formed in alkaline media in the presence of various anions
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ABSTRACT: The tendency of Pu(IV) to hydrolyze and form true solutions, colloid solutions, or insoluble precipitates has been known since the Manhattan Project. Since then, specific studies have been performed to examine in detail the equilibria of Pu(IV) hydrolytic reactions in various media. Great attention also has been paid to the preparation, structure, and properties of Pu(IV) polymers or colloids. These compounds found an important application in sol-gel technology for the preparation of nuclear fuel materials. A most important result of these works was the conclusion that Pu(IV) hydroxide, after some aging, consists of very small PuO{sub 2} crystallites and should therefore be considered to be Pu(IV) hydrous oxide. However, studies of the properties and behavior of solid Pu(IV) hydroxide in complex heterogeneous systems are rare. The primary goal of this investigation was to obtain data on the composition and properties of Pu(IV) hydrous oxide or other compounds formed in alkaline media under different conditions. Such information is important to understand Pu(IV) behavior and the forms of its existence in the Hanford Site alkaline tank waste sludge. This knowledge then may be applied in assessing plutonium criticality hazards in the storage, retrieval, and treatment of Hanford Site tank wastes as well as in understanding its contribution to the transuranic waste inventory (threshold at 100 nCi/g or about 5 {times} 10{sup {minus}6} M) of the separate solution and solid phases.08/1998; -
Article: Interaction of Pu(IV,VI) hydroxides/oxides with metal hydroxides/oxides in alkaline media
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ABSTRACT: The primary goal of this investigation was to obtain data on the possibility, extent, and characteristics of interaction of Pu(IV) and (VI) with hydroxides and oxides of d-elements and other metals [Al(III), LA(III), and U(VI)] in alkaline media. Such information is important in fundamental understanding of plutonium disposition and behavior in Hanford Site radioactive tank waste sludge. These results supply essential data for determining criticality safety and in understanding transuranic waste behavior in storage, retrieval, and treatment of Hanford Site tank waste.07/1998; -
Article: Reaction of Np(VI) and Pu(IV) with heteroblues in aqueous solutions
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ABSTRACT: Reactions of heteroblues SiMo{sub 12}, PMo{sub 12}, PV{sub 2}Mo{sub 10}, PV{sub 6}Mo{sub 6}, and P{sub 2}W{sub 18} with Np(VI) and Pu(IV) in HCl and HNO{sub 3} solutions are studied by spectrophotometry. The species Np(VI) is quickly reduced by all five blues. The species Pu(IV) is reduced by the first four blues if the solution of heteroblue is added to the Pu solution and is not reduced by any blues if they contain HNO{sub 3}.Radiochemistry 12/1994; 36(3).
