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Abstract  

Self-diffusion of Co2+ ions in CoBr2 and CoI2 is reported in the concentration range of 10–5 to 0.25M in 1% agar gel at 25 °C. The deviations observed between the experimental and theoretical values of diffusion coefficients are explained by considering different types of interactions occurring in the ion-gel water system. The applicability of the transition state theory to the diffusion of ZnSO4 in agar gel medium is tested by varying the temperature as well as the gel concentration at high concentration of the electrolyte. The activation energy E and D 0 value decrease with increasing gel concentration in agreement with the theory.

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Abstract  

The values of activation energy required for the diffusion of ZnCl2 and for Cd2+ ions in Cd/Ac/2 are reported in agar gel medium at 5×10–5 and 0.001M concentration, respectively. These values are compared with the previously reported values in the same systems at different concentrations. The decrease in activation energy with concentration of electrolyte is in agreement with the Wang's model.

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Abstract  

Formation of adducts between U(TTA)4 and several neutral donors was studied by spectrophotometry and it was shown that each of the neutral donors forms only 1∶1 adduct with U(TTA)4. The adduct formation constants with some neutral donors were determined for benzene and chloroform media. As these adducts are involved in the synergistic extraction of U(IV) from aqueous media by mixtures of HTTA and neutral donors dissolved in organic solvents, the extraction equilibrium constants were estimated, The adduct formation was found to result in an increase of the co-ordination number of U(IV) from 8 in U(TTA)4 to 9 in the adducts it forms with the neutral donors. Similar absorption spectral studies with U(DBM)4 revealed that it forms much weaker adducts than the corresponding ones with U(TTA)4.

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Abstract  

The activation energy of the tracer diffusion of Mn2+ ions in alkali chlorid solutions (0.1M) has been determined in agar gel medium (1–2.5%) over the temperature range of 25–45 °C. The decrease in the value of the Arrhenius parameters, E and D 0, with gel percentage is explained on the basis of the transition state theory. Further, the activation energy as a function of electrolyte concentration is also investigated using 1% agar gel in the temperature range of 25–45 °C. In both the cases, the activation energies are determined by the least square fitting of the diffusion coefficient data obtained at various temperatures through the Arrhenius plots.

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Abstract  

The obstruction effect for tracer-diffusion of Mn2+ ions in the presence of different supporting electrolytes (LiCl, NaCl, KCl, CsCl) at various concentrations has been studied at 25 °C using the zone diffusion technique. It has been observed that the obstruction effect determined in terms of increases with concentration of the electrolyte. Further, for a given concentration it is found to decrease with increasing charge density of the cation. We also report here on the effect of temperature on obstruction and found that is constant over the temperature range studied (25–45 °C). These observations are explained on the basis of competitive hydration between ions and agar macromolecules.

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Abstract  

Radiation decomposition studies of quenched pure KNO3 and KNO3 doped with Ba2+ ions in the presence of PbO or Al2O3 as a heterophase impurity showed that the yield of nitrite varied with the particle size of the nitrate. The G/NO 2 / values were also found to vary with the mol percent of PbO or Al2O3 in the mixture. Higher yields of nitrite were obtained in the presence of PbO, while in mixtures containing Al2O3, the yields of nitrite were lower in comparison with the G-values observed in the absence of oxide. These results are explained on the basis that a larger surface area results in an increased energy transfer at the interface between two neighbouring particles. The results can also be accounted for in terms of electron donor-acceptor properties of the added oxides.

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Abstract  

Current status on the chemical aspects of nuclear fuel reprocessing is presented with special emphasis on the Purex process which continues to be the process of choice for the last four decades. Better decontamination from fission products, new methods for uraniumplutonium partitioning and removal of actinides from high active waste are challenging areas in process chemistry. The development work on TRUEX and DIAMEX process for treating high active waste is briefly described. An overview of pyrochemical processes, which are important for Integral Fast Reactor Concept, is presented.

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Abstract  

The diffusion of some zinc and cobalt salts in water have been measured using an improved version of the capillary technique. In this technique, diffusion proceeds in the absence of stirring in the bulk solution. The amount of diffusing substance which remains in the capillary is analyzed after a chosen time. Nanis' solution for three-dimensional diffusion from a capillary has been used to calculate the experimental values. The values of diffusion coefficient of zinc iodide, cobalt bromide and cobalt iodide have been obtained with a diffusion run time of four hours. A comparison has been made between the experimental and theoretical values obtained from Onsager-Fuoss theory. An attempt has also been made to explain the deviation between the experimental and theoretical values over the concentration range studied.

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Abstract  

Tracer-diffusion of Zn2+ ions in the presence of CoSO4 is studied at 25°C in 1% agar gel over a concentration range of 10–5 to 0.25M using a zone-diffusion technique. The deviations observed between experimental and theoretical values of diffusion coefficients are explained by considering different types of interactions occurring in the ion-gel-water system. Further, study of the obstruction, effect in the diffusion of Zn2+ ions at different concentrations of CoSO4 reveals that the -value decreases with increasing concentration of the electrolyte. This observation is accounted on the basis of competitive hydration between ions and agar molecules.

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Abstract  

The activation energy for the diffusion of ZnSO4 as a function of electrolyte concentration is computed by least squares fitting of the diffusion coefficient data obtained at various temperatures in the Arrhenius equation. It is observed that the activation energy decreases with increasing concentration of the electrolyte. This observation is accounted for on the basis of Wang's model. Further, the obstruction effect caused by the agar macromolecules in the diffusion path of ZnSO4 uis also determined at these concentrations by varying the gel concentration at 25°C., The obstruction effect expressed in terms of a found to decrease with ZnSO4 concentration and explained on the basis of competitive hydration of diffusing ions and agar molecules.

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