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Abstract  

The oxidation-reduction reaction between U(VI) and Ti(III) in HCl solution was studied spectrophotometrically. The reaction is second-order at all concentrations of reactants, HCl, ferrous chloride and mannitol used in this work. In 5M HCl the rate constantk increases with increasing Ti(III) concentration, whereas it decreases with increasing U(VI) concentration, with increasing HCl concentration from 1.00M to 7.17M and increases thereafter from 7.17M to 11.79M. The addition of mannitol causes a consistent decrease in the rate of reaction, whereas ferrous chloride has no effect. The activation energy for this oxidation-reduction reaction was 47.90±0.11 kJ·mol–1. The values of H , G and S were 45.40±0.11 kJ·mol–1, 72.50±0.17 kJ·mol–1 and –91.10±0.22J·k–1·mol–1, respectively. The mode of reaction is discussed in the light of kinetic results.

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Abstract  

The mechanism of the reduction reaction of lanthanide(III) ions by hydrated electrons in polar solvents has been investigated. The theoretical rate constants for the reaction of hydrated electrons with a number of lanthanide ions have been calculated using the energy gap laws of the charge shift reaction(D+−A→D−A+) and compared with experimental values. With these results, we have explained the large difference of the reaction rates of lanthanide ions with hydrated electrons, which depend upon the kind of lanthanide ion. The calculated results agree almost quantitatively with the experimental values.

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Abstract  

The kinetics of reduction reactions between N,N-dimethylhydroxylamine (DMHAN) and plutonium(IV) in nitric acid solution have been studied spectrophotometrically. The kinetic equation of the reaction is determined to be -d[Pu(IV)]/dt = k 0[Pu(IV)][DMHAN]1.18/[H+]2.22 at the beginning, where, the rate constant of the reaction (k 0) is 10.5 ± 1.8(mol/L)1.04 s−1 at 14.5 °C. By regressing of the time-concentration curve of the reaction, The complete rate equation is calculated as
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$- {\frac{\rm{d[Pu(IV)]}}{{{\rm{d}}t}}} = {\frac{{k [{\rm{Pu(IV)]}}^{ 2} [ {\rm{DMHAN]}}^{ 1. 1 8} / [ {\rm{H}}^{ + }]^{ 2. 2 2} }}{{ 8. 1 2 [ {\rm{Pu(III)]}} + 9 5. 9 [{\rm{Pu(IV)]}}}}}$$ \end{document}
with the reaction constant k about 1,000(mol/L)1.04 s−1 at 14.5 °C and an ionic strength (μ) of 4.0 mol/L.
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Abstract  

The kinetics of oxidation-reduction reaction between N,N-diethylhydroxylamine (DEHAN) and neptunium (VI) in nitric acid media has been studied by spectrophotometry at 25.2 °C. The rate equation is -d[Np(VI)/dt=k[Np(VI)][DEHAN]/[H+] found by investigating the influence of concentration, acidity, ionic strength and temperature on the reaction. The rate constant of the reaction k is 23.0±1.8 min–1 for = 2.0 mol/l. A possible mechanism of reaction has been suggested according to the ESR spectra of nitroxide radical produced in the DEHAN+V(V) system.

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Abstract  

The solvent-free reduction of benzophenone and five substituted benzophenones with sodium borohydride to the corresponding alcohols was studied by thermal analysis, X-ray powder diffractometry, NMR spectroscopy, and scanning electron microscopy. In most cases, the reaction occurs via liquid eutectic phases that are formed between the benzophenone and the resulting benzohydrol. Nevertheless, this reaction can be carried out without the need for a solvent, leading to pure alcohol without side products. In some cases, heating may be necessary to achieve a reasonably short reaction time. In conclusion, this reaction type appears to be feasible as a preparative organic reaction that avoids a solvent.

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bulk counterpart and of its potential applications. It has been emphasized that reduction reactions in solution at the nanoscale are often controlled kinetically rather than thermodynamically [ 26 ]. Gathering kinetic data for the formation of Cu

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Abstract  

Oxidation-reduction reactions were studied for the following oxocuprates: LiCuO, Li2CuO2, SrCu2O2, Sr2CuO3, SrCuO2, BaCu2O2, BaCuO2,LaCuO2, La2CuO4, Ca2CuO3 and Bi2CuO4. Transformation schemes have been proposed for the anionic sub-lattices of these salts and the effect of cations on the properties of the anionic sub-lattices in oxidation-reduction reactions was determined.

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Abstract  

A method for quantitatively estimating the fractions of plutonium oxidation states that derive from disproportionation, or other oxidation-reduction reactions, is illustrated with data for seawater. The results agree with experiment and can be checked numerically. Attention is drawn to a discrepancy in what we think is known about seawater.

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Hydroxylamine derivatives in Purex Process

I. Study on the kinetics of redox reaction between N,N-diethylhydroxylamine and nitrous acid

Journal of Radioanalytical and Nuclear Chemistry
Authors: Zhang Anyun, Hu Jingxin, Zhang Xianye, and Wang Fangding

Abstract  

The kinetics of oxidation-reduction reaction between N,N-diethylhydroxylamine (DEHAN) and nitrous acid in nitric acid solution have been studied by spectrophotometry at 9.5°C. The rate equation is −d[HNO2]/dt=K[HNO2]·[DEHAN][HNO3] and the rate constantK=12.81 (mol/l)−2·min−1. A possible mechanism has been suggested on the basis of chemical analysis and Raman spectra. The activation energyE and the thermodynamic functions ΔH #, ΔG # and ΔS # are also calculated.

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Abstract  

The kinetics of oxidation-reduction reactions between N,N-diethylhydroxylamine (DEHAN) and plutonium(IV) in nitric acid solution have been studied by spectrophotometry at 25.2 °C. The initial rate equation of the reaction is -d[Pu(IV)]/dt=k 0[Pu(IV)]2[DEHAN]1.26/[H+]2.53, where the rate constant of the reaction (k 0) is (5.93±0.84).103 (mol/l)0.27 min-1. The complete rate equation and the rate constants of the reaction are also derived.

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