Temperature dependence of the intensity of phonon-free luminescence lines of Rb3UO2F5 crystals in the 4.2–40 K range

We have investigated the behavior of the intensity of phonon-free lines appearing in the luminescence spectra of Rb₃UO₂F₅ crystals in the 4.2–40 K range due to a pure electron transition and its vibrational recurrences with the frequency of fully symmetrical stretching vibrations of the uranyl ion. It is shown that the temperature dependence of the total integrated intensity of these phonon-free lines, I_Σ, can be described using a model of configuration coordinates of an impurity center with one local vibration. An empirical expression has been obtained for the dependence I_Σ = I_Σ(T) in the form of the product I_Σ(T) = I₀(T)S_Σ(T), where the first factor describes the temperature dependence of the integrated intensity of the pure electron transition line and the second can be approximated by an exponential function of the Stokes parameter. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 129–131, January–February, 2000.     

Performance of group additivity methods for predicting the stability of uranyl complexes

Herein, we investigated the viability of two group additivity methods for predicting Gibbs energies of a set of uranyl complexes. In first place, we proved that both density functional theory (DFT)-based methods and Serezhkin's stereoatomic model provide equivalent answers in terms of stability. Moreover, we proposed a novel methodology based on Mayer's population analysis for estimating Serezhkin's empirical parameters theoretically. On the other hand, we showed that Cheong and Persson linear algebra methodology can be successfully applied to uranyl complexes, and analyzed its performance in connection with the chemical nature of the compounds employed in the model.     

Some angular| dependences of the ion-electron emission coefficient

In the cases when primary ion beam direction is aligned with close-packed planes the dependences of the reduced coefficient of ion-electron emission on various angles has been studied. It was found that there are such ranges of azimuthal angle and angle of incidence of primary ion beam within which the reduced coefficient is determined mainly by the angle between the primary ion beam and close-packed plane only.     

Recent R&D towards Aqueous Reprocessing of FBR Fuels

The mixed Pu-rich carbide spent fuel with a burn up of 155 GWd/t from the Fast Breeder Test Reactor is being reprocessed in a hot-cell facility by PUREX process. Based on the input from the operation of this facility, R&D activities were carried out to improve the recovery, decontamination factors, economy and to reduce the waste volumes. Reduction of uranyl ions in a continuous flow electrochemical reactor and electrolytic as well as chemical reduction of 4M HNO₃ from liquid waste could be accomplished in continuous mode. Using the optimized parameters, suitable electrolytic cells/experimental setups were designed for the plant capacity of 6 L/h. Studies on the extraction kinetics of Ru with 30% TBP in NPH revealed that better decontamination factor with respect to Ru can be achieved using fast contactors like centrifugal extractors (CEs). Towards developing a spent solvent recovery system to reduce organic waste volumes, a pilot plant was set up, which could recover diluent as top product of distillation column and 40% TBP as bottom product from inactive degraded solvent. A solvent recovery system using short path distillation was also developed for installation in hot cells.     

Adsorption of Uranium (VI) Ions on Hydrazinyl Amine and 1,3,4-Thiadiazol-2(3 H)-thion Chelating Resins

Nitrogenous compounds are the most widely used in solid phase extraction due to its low cost, easy convertible to many functional groups. These have large adsorptive capacity toward heavy metal ions as rare earth elements (REEs) and uranium with ability for recovering from low concentrate solutions. Synthesis of resins were carried out by polymerization of acrylonitrile with divinyl benzene as crosslinker. Treatment of the resulted precipitate with hydrazine hydrate in ethanol produce hydrazinyl methyl amine which has high chelating capacity toward uranyl ions. 1,3,4-Thiadiazol-2(3H)-thion derivative was yielded by reaction of hydrazinyl amine with carbon disulfide in methanol. This reaction carried out in the presence of methyl benzoate and dioctyl phthalate as pore producing solvent which used to improve physical properties and adsorptive character of the resins. Optimization on the two resins during loading and elution were carried out using solution with different concentrations. The optimum factors during adsorption and elution were recognized.     

Donor Properties of Ligands and the Structure and Spectra of Uranyl Halogenides in the Solid State

Complexes of uranyl halogenides with neutral organic ligands in the solid state have been obtained, the luminescence spectra at T = 77 K have been recorded, and the dependences of them on the composition of the complex have been investigated. The linear dependence of the change in the frequencies of electron and vibronic transitions on the donor number of the neutral ligands has been revealed, thus allowing us to propose a spectral method for determining the structure of the system studied. It is shown that the increased strength of the bond of some halogen ligands (in particular, fluorine) with uranyl favors the nonsaturation of their inner coordination sphere. At the same time, the most stable complexes of the substances considered are formed when two halogen ions are supplemented with three molecules of organic ligand.     

一种铀(Ⅵ)配合物的水热合成、结构与性质

UO₂(EPC)₂ (EPC=5-ethyl-3-pyridinecarboxylate) was synthesized by the hydrothermal reaction of UO₂(NO₃)₂ ·6H₂O with imazethapyr [2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-5-ethyl-3-pyridine-carboxylic acid] at 120 ℃, which 2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl group was removed under this condition to result in the formation of 5-ethyl-3-pyridinecarboxylate ligand (EPC). The structure and fluorescent property of the synthesized complex is also reported. CCDC: 645641.     

乙二胺杂化锗酸锌纳米带的绿色合成及其对铀酰离子的吸附与检测

该文采用水热法合成了一种新型乙二胺杂化的锗酸锌纳米带(NH₂-Zn₂GeO₄ NRs),并用于铀酰离子(UO₂²⁺)的检测和吸附。利用透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、X射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)以及荧光光谱等对纳米带的结构及其光学特性进行了表征。结果表明NH₂-Zn₂GeO₄ NRs表面含有大量的—Ge—O—H和—NH₂基团,为UO₂²⁺的检测和吸附提供了丰富的结合位点。此外NH₂-Zn₂GeO₄ NRs可高效、高选择性地吸附和检测UO₂²⁺,其对UO₂²⁺的吸附符合Langmuir等温模型,最大吸附量为190 mg...