Tail-end purification of americium from plutonium loading effluents using a mixture of octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide and tri-N-butyl phosphate

The tail-end purification of Am from Pu loading effluents in 7.5M HNO₃ containing 160 mg l^–1 Am and 1.2 mg l^–1 Pu has been carried out. With 0.2M CMPO+1.2M TBP in dodecane as the extractant and stripping by 0.04M HNO₃+0.05M NaNO₂, the Pu level is brought down to 31.2 g l^–1. When the acidity was reduced to 4.2M HNO₃, one contact with 20% TLA/dodecane and subsequent extraction by a mixture of CMPO and TBP and stripping with 0.04M HNO₃+0.05M NaNO₂ gave Am samples without any detectable amounts of Pu. The recovery of Am was 90% by the first procedure and 98% by the second one.     

Studies on the SMSI of Rh/ZnO by XPS and XAES and its effect on CO?H2 reaction

XPS and XAES studies have been used to establish SMSI effect in Rh/ZnO catalyst prepared from Rh₆(CO)₁₆ and reduced at high temperature. The interaction occurs between Rh metals and reduced Zn cations resulting an increase in the electron density on rhodium. The role of SMSI effect in the catalytic hydrogenation of CO has been examined.

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Rh/ZnO, Rh₆(CO)₁₆ . Rh Zn, . CO.

     

Convenient Routes for the Preparation of Barium Permanganate and other Permanganate Salts

Two convenient methods were developed to transform KMnO₄ into barium permanganate and other permanganate salts via BaMnO₄ or Mn₂O₇ intermediates. Pure BaMnO₄ was prepared by the reaction of KMnO₄ with KI in the presence of BaCl₂ and NaOH. Hydrothermal reaction of barium manganate with excess carbon dioxide for 1.5 h at 100 °C led to barium‐permanganate with almost quantitative yield. Mn₂O₇ was prepared by means of the reaction of KMnO₄ and sulfuric acid monohydrate in a two‐phase (CCl₄‐H₂SO₄.H₂O) system. In the presence of excess barium carbonate and catalytic amount of water barium permanganate could be obtained with a moderate yield. Similarly, other permanganate salts (Zn, Cd, Cu, Mg, Ca, Ni, Al, Fe, Ce, rare earth metals) were prepared by substituting the BaCO₃ for the appropriate metal oxides, hydroxides or carbonates.     

Kinetics and mechanism of the oxidation of DL-methionine bybis(2,2′-bipyridyl)copper(II) permanganate

Summary The oxidation ofDL-methionine (MT) bybis(2,2-bipyridyl)copper(II) permanganate (BBCP) to the corresponding sulphoxide is first order in BBCP. Michaelis-Menten-type kinetics were observed with respect to MT. The formation constant of the intermediate complex and the rate constant for its decomposition were evaluated. The thermodynamic and activation parameters were also evaluated. The reaction is catalysed by H⁺ but 2,2-bipyridine does not affect the reaction rate. A mechanism is proposed.     

A DFT‐based exploration augmented by X‐ray and NMR of the stereoselectivity in the 1,3‐dipolar cycloaddition of 1‐pyrroline‐1‐oxide to methyl cinnamate and benzylidene acetophenone

A B3LYP/6–31G* study was carried out for the reactions of 1‐pyrroline‐1‐oxide (N1) with methyl cinnamate (E1) and benzylidene acetophenone (E2) for getting a quantitative rationalization of the experimental findings. The product ratios were determined by NMR studies of the crude reaction mixtures. The conformation and stereochemistry of the isolated cycloadducts were finally confirmed by 2D NMR and X‐ray diffraction. The endo/exo‐selectivities were predicted through the computation of activation parameters on the basis of assumed concerted mechanism. The regioselectivity and reactivity were amply predicted by local and global electrophilicity indices and were found to be in good agreement with the experimental findings which were supportive of polar character and of the direction of charge transfer (CT) accompanying the cycloaddition. It was found that the cycloaddition involving methyl cinnamate was endo‐selective, while that with benzylidene acetophenone produced the exo‐isomer as the major adduct. Copyright © 2010 John Wiley & Sons, Ltd.     

A two‐component two‐phase dissipative particle dynamics model

Dissipative particle dynamics (DPD)‐based models for two‐phase flows are attractive for simulating fluid flow at the sub‐micron level. In this study, we extend a DPD‐based two‐phase model for a single‐component fluid to a two‐component fluid. The approach is similar to that employed in the DPD formulation for two immiscible liquids. Our approach allows us to control the density ratio of the liquid phase to the gas phase, which is represented independently by the two components, without changing the temperature of the liquid phase. To assess the accuracy of the model, we carry out simulations of Rayleigh–Taylor instability and compare the penetration rates of the spikes and bubbles formed during the simulations with prior results reported in the literature. We show that the results are in agreement with both experimental data and predictions from Youngs' model. We report these results for a broad range of Atwood numbers to illustrate the capability of the model. Copyright © 2008 John Wiley & Sons, Ltd.     

Kinetics and Mechanism of the Oxidation of Somethioacids by Benzyltrimethylammonium Tribromide

The oxidation of thioglycollic, thiolactic and thiomalic acids bybenzyltrimethylammonium tribromide proceeds through the formation of asulfenium cation in the slow step.