Molybdate Complexes of Np(V) with Outer-Sphere Cs+ Cations

Radiochemistry - Structure of two new molybdate complexes of Np(V) with composition of Cs2[(NpO2)2(MoO4)2(H2O)]·H2O (I) and Cs3[(NpO2)(MoO4)2] (II) has been studied. In structure I, two...     

Nitrate Complexes of Neptunium(V) with Alkali Metal Cations in the Outer Sphere

Radiochemistry - Nitrate complexes of pentavalent neptunium with alkali cations in the outer sphere, with composition Li[NpO2(NO3)2]·2H2O (I), Na[NpO2(NO3)2]·2H2O (II),...     

Complexes of Np(VI) with Cyclobutanecarboxylic Acid Anions and Single-Charged Cations in the Outer Sphere: [NH4][NpO2(cbc)3], [C(NH2)3][NpO2(cbc)3], and [N(CH3)4][NpO2(cbc)3]

Radiochemistry - Three new Np(VI) complexes with cyclobutanecarboxylic acid anions and single-charged outer-sphere anions: ammonium, [NH4][NpO2(cbc)3] (I), guanidinium, [C(NH2)3][NpO2(cbc)3] (II),...     

Kinetics of Pu(VI) Reaction with Ethylenediaminetetraacetic Acid

Radiochemistry - The spectrophometric method was used to examine the stoichiometry of the reaction of Pu(VI) reduction by EDTA ions in 0.05–0.5 M HClO4 solutions at a temperature of 23°C...     

Np(VI) Reduction with Diformylhydrazine in Perchloric Acid Solutions

Radiochemistry - The stoichiometry of the reaction of Np(VI) with diformylhydrazine N2H2(CHO)2 (DFH), in 0.01 and 0.1 M HClO4 solutions was studied by spectrophotometry. At an excess of Np(VI), 1...     

Kinetics of Np(VI) Reduction with Diformylhydrazine in Nitric Acid

The kinetics of the Np(VI) reduction with diformylhydrazine in a nitric acid solution was studied by spectrophotometry. The reaction rate increases with an increase in the reductant concentration and temperature and decreases with an increase in the HNO₃ concentration. The reaction order with respect to Np, diformylhydrazine, and HNO₃ is 1, 1.3, and–1.55, respectively. The activation energy of the reaction is 85 ± 10 kJ mol^–1.     

Kinetics of Pu(VI) Reduction with Diformylhydrazine in Nitric Acid

The kinetics of the Pu(VI) reduction with diformylhydrazine in a nitric acid medium was studied by spectrophotometry. The reaction rate increases with an increase in the reductant concentration and temperature and decreases with an increase in the HNO₃ concentration. The reaction order with respect to Pu, diformylhydrazine, and HNO₃ is 1, 1.3, and–1.5, respectively. The activation energy of the reaction is 86.9 kJ mol^–1.     

碱土金属长余辉材料的耐酸碱性研究

分别对发光性能最好的铝酸盐基质长余辉材料SrAl2O4∶Eu2+,Dy3+与硅酸盐基质长余辉材料Sr2MgSi2O7∶Eu2+,Dy3+进行酸、碱处理(以HNO3和NaOH为例),研究其耐酸碱性能。XRD、SEM、激发光谱、发射光谱以及余辉特性测试的结果表明:SrAl2O4∶Eu2+,Dy3+及Sr2MgSi2O7∶Eu2+,Dy3+经酸、碱处理后物相发生了部分改变,其激发与发射光谱的强度随着酸碱度的增大而降低,但峰形与峰位没有改变;SrAl2O4∶Eu2+,Dy3+经酸碱处理后表面变得更不平整,棱角变得不明显;SrAl2O4∶Eu2+,Dy3+经酸处理后的初始亮度为未处理时的39.2%,经碱处理后的初始亮度为未处理时的14.0%;Sr2MgSi2O7∶Eu2+,Dy3+经酸碱处理后晶体的结构、形貌、表面及余辉衰减情况基本无变化。     

Catalytic Reduction of Np(VI,V) with Formic Acid in Perchloric Acid Solutions

Neptunium(VI) is successively reduced with formic acid to Np(V) and Np(IV) in perchloric acid solutions in the presence of 1% Pt/SiO₂ catalyst. The kinetic features of Np(VI,V) reduction with formic acid in 0.1-4.0 M HClO₄ in the presence of 0.01-0.1 g ml^-1 of 1% Pt/SiO₂ at [HCOOH] = 0.001-1.0 M and T = 40-70°C were studied. The rate-determining steps of reduction of Np(VI) to Np(V) and Np(V) to Np(IV) are diffusion and decomposition of the activated complex adsorbed on the catalyst surface, respectively. The mechanisms of both processes are discussed.     

Reduction of Np(VI) with Carbohydrazide in a Perchloric Acid Solution

Radiochemistry - The stoichiometry of the reaction of Np(VI) with carbohydrazide (NH2NH)2CO in a 0.02 M HClO4 solution was studied by spectrophotometry. With Np(VI) taken in excess, 1 mol of...     

Reduction of Np(VI) with Hexamethylenetetraacetic Acid in HClO4 Solution

Radiochemistry - Spectroscopic method was used to examine the stoichiometry of the reaction of No(VI) with hexamethylenediaminetetraacetic acid (HMDTA, H4hmdta) in a 0.05 M HClO4 solution. At an...     

Kinetics and Mechanism of Pu(VI) Reduction with Acetaldoxime in Nitric Acid Solution

Reduction of Pu(VI) to Pu(III) with acetaldoxime (CH₃CHNOH) in an HNO₃ solution involves three consecutive steps Pu(VI) → Pu(V) → Pu(IV) → Pu(III), and also reproportionation of Pu(IV). Complete kinetics equations of these steps were derived and the rate constants and activation energies of these steps were determined by computer treatment of the experimental kinetic data for all Pu valence forms. The mechanisms of these reaction steps based on the experimental results were discussed.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 67–71.Original Russian Text Copyright © 2005 by V. Koltunov, Pastushchak, Mezhov, G. Koltunov.     

Complexation of An(VI) (An = U, Np, Pu, Am) with 2,6-pyridinedicarboxylic acid in aqueous solutions. Synthesis and structures of new crystalline compounds of U(VI), Np(VI), and Pu(VI)

Complexation of An(VI) (An = U, Np, Pu, Am) with 2,6-pyridinedicarboxylic (dipicolinic) acid in aqueous solutions was studied. All these actinides form with dipicolinic acid anion, PDC^2? 1: 1 and 1: 2 complexes. The PDC^2? ion coordinates to actinide(VI) ions in solutions in tridentate fashion. In 1: 2 complexes, the f-f transition bands in the electronic absorption spectra are very weak, which is associated with approximate central symmetry of the coordination polyhedron (CP) of the An atom. The apparent stability constants of Pu(VI) complexes were measured in a wide pH range, and the concentration stability constants of An(VI) (An = U, Np, Pu, Am) were determined. The crystalline complexes [Li₂AnO₂(PDC)₂]·2H₂O (An = U, Np, Pu) and [AnO₂(PDC)] _n (An = Np, Pu) were synthesized, and their structures were determined by single crystal X-ray diffraction. The X-ray data confirmed the conclusion that CP of An atoms in the complex ions AnO₂·(PDC) ₂ ^2? is centrosymmetrical. In the isostructural series of [Li₂AnO₂(PDC)₂]·2H₂O, the actinide contraction is manifested in shortening of the An-O distances in the “yl” groups in going from U to Pu.     

Catalytic Reduction of U(VI) with Hydrazine and Formic Acid in HNO3 Solutions

Catalytic reduction of 0.75 M U(VI) with hydrazine in HNO₃ solutions was studied under various conditions. At 58°C up to 0.55 M U(IV) is accumulated within 2 h in solutions containing 1-1.5 M N₂H₅ ⁺ and 2 M HNO₃ in the presence of 1% Pt/SiO₂ (S : L = 1 : 10). The reduction is decelerated with decreasing N₂H₅ ⁺ concentration to 0.75 M or with increasing HNO3 concentration to 3-4 M. 1.2 mol of U(IV) is formed per mole of oxidized hydrazine. Uranium(VI) reduction with formic acid in the presence of 1% Pt/SiO₂ and 1% Pt/VP-1An anion exchanger was studied. There exists a threshold N₂H₅ ⁺ concentration below which U(VI) is not reduced. The reduction in solutions containing 1-2 M HCOOH, 1-2 M HNO₃, and 0.1 M N₂H₅ ⁺ is faster than in solutions free of formic acid and containing 1-1.5 M N₂H₅ ⁺.     

Reduction of Np(VI) and Pu(VI) with anions of some substituted carboxylic acids

The reaction of Np(VI) with organic acid anions in solutions containing lithium salts of tartaric, malic, α-aminoglutaric, and trihydroxyglutaric acids was studied. Changes in the solution spectra show that Np(VI) forms complexes with organic acid anions, which is followed by the reduction of Np(VI) to Np(V). Similar processes occur in solutions containing Pu(VI) and sodium phenylglycolate or ammonium salicylate. In weakly acidic solutions, the loss of the Np(VI) and Pu(VI) concentrations is a linear function of time. The possible mechanism of the redox reactions was suggested.     

Neptunium(VI) and Plutonium(VI) Pyrazine-2-carboxylates

New Np(VI) and Pu(VI) pyrazine-2-carboxylates isostructural with the uranyl complex [UO₂ · (C₄H₃N₂COO)₂(H₂O)] · 2H₂O were synthesized from aqueous solutions. The unit cell parameters of [NpO₂ · (C₄H₃N₂COO)₂(H₂O)] · 2H₂O and [PuO₂(C₄H₃N₂COO)₂(H₂O)] · 2H₂O were calculated from the powder X-ray patterns. The thermal behavior of the complexes suggests that the Np(VI) compound contains superstoichiometric water molecules, which are also manifested in the IR spectrum. The absorption spectra of the compounds show that the pyrazinecarboxylic acid anion is a strong complexing agent with respect to Np(VI) and Pu(VI).__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 35–38.Original Russian Text Copyright © 2005 by Andreev, Budantseva, Perminov, Fedoseev.     

Uranium(IV) Complexes Formed in Extraction with Tributyl Phosphate from Nitric Acid Solutions

Speciation of U(IV) in tributyl phosphate (TBP) solutions prepared by extraction of U(IV) from 2 M HNO₃ was studied. The electronic spectra showed that in the solutions containing from 3 to 60% TBP a mixture of disolvate U(NO₃)₄(TBP)₂ and hydrates with hypothetical formula (TBP) _m ...[U(NO₃) _k · (H₂O) _n ]^(4-k)+ (k = 3 or 4) is formed. Within the 70-100% concentration range, the hexanitrate complex (TBP) _n ...2H₅O₂(H₂O) _p ⁺...[U(NO₃)₆]^{2 -} also appears. In undiluted TBP, as the concentration of uranyl nitrate increases, first the hexanitrate complex and then hydrated complexes of U(IV) gradually disappear. At uranium concentration more than 300 g l^-1, only U(IV) tetranitrate disolvate exists in the organic phase.     

非过渡金属催化芳香二炔和二硅烷基苯制备聚(硅苯-芳炔)树脂

以芳香基双炔和1,4-二(二甲基硅烷基)苯为原料,乙二醇二甲醚(DME)为溶剂,NaO H为催化剂,空气氛围下,一步反应制备得到含硅芳炔树脂(SPAR).并进一步探讨了催化剂、反应溶剂、温度、时间对聚合反应的影响.通过凝胶渗透色谱(GPC)、红外光谱、核磁分析确定产物的分子量和化学结构.实验结果表明:使用20 mol％...     

Synthesis and properties of Np(VI) and Pu(VI) monophthalates

Neptunium(VI) and plutonium(VI) monophthalates were prepared and characterized. The complexes AnO₂ (COO)₂C₆H₄ 2H₂O were isolated from cold solutions, and AnO₂ (COO)₂C₆H₄ 1.33H₂O, from hot solutions. NpO₂ (COO)₂C₆H₄ b. 2H₂O and PuO₂ (COO)₂C₆H₄ 2H₂O crystalize in the triclinic and monoclinic systems, respectively. The complexes AnO₂(COO)₂C₆H₄ 1.33H₂O are isostructural and crystallize in the rhombohedral system. The thermal behavior of these complexes was studied. Their IR and electronic absorption spectra were recorded. The properties of these complexes were compared to those of known U(VI) monophthalates.Translated from Radiokhimiya, Vol. 46, No. 5, 2004, pp. 389–395.Original Russian Text Copyright © 2004 by Krot, Bessonov, Grigorev, Charushnikova, Makarenkov.