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Abstract  

The possibility of the use of chlorinated cobalt dicarbolide, H+C4B18H15Cl7Co, it nitrobenzene for the selective extraction of137Cs from mixtures of95Zr−95Nb,106Ru-106Rh and144Ce was studied. The effect of aqueous phase acidity on the distribution ratio of Cs, Ru and Zr as well as the effect of the amount of isotopic and non-isotopic carriers of alkali metals on the distribution ratio were determined. Separation factors for cesium from ruthenium, zirconium and cerium were calculated, all being extracted from nitric acid solutions. The efficiency of cesium separation was verified by gamma-spectrometry.

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Abstract  

The complexes of cobalt(II) with dothiepin (DOT) hydrochloride have been studied for kinetics of thermal degradation by thermogravimetric analysis (TG) and derivative thermogravimetric studies (DTG) in a static nitrogen atmosphere at a heating rate of 10 C min−1. A general mechanism of thermal decomposition is advanced involving dehydration and decomposition process for both organic and inorganic ligands. The thermal degradation reactions were found to proceed in three steps having an activation energy in the range 6.75–170 kJ mol−1. Thermal decomposition kinetics parameters were computed on the basis of thermal decomposition data.

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Abstract  

The present work discusses the complexation behavior of bioligand cysteine with cobalt and the immobilization of this complex (Co–Cys) onto a biocompatible ligand and common drug base, polyvinylpyrrolidone (PVP). The complexation behavior has been studied by radiometric method and UV–Vis spectrophotometry. The radiometric method involves dialysis of 60Co–Cys–PVP complex against triple distilled water which subsequently gives the dynamic dissociation constant (k d) of the complex. The half life of 60Co–Cys–PVP complex calculated from k d value is 22.6 h against triple distilled water at pH 8.5. The UV–Vis spectra analysis confirms the complexation of Co with cysteine at this pH and also indicates that the cysteine ligated Co(II) centers easily get oxidised to Co(III) centers (low spin, d6) in the presence of air at alkaline pH showing no d–d transitions.

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Abstract  

The sorption behaviour of cobalt and cadmium by Mexican erionite was studied at different pH values and the ion exchange isothems were determined. Sorption experiments were performed with cobalt and cadmium solutions. The cobalt, cadmium and sodium content in the aluminosilicate samples were determined by neutron activation analysis. It was found that the sorption for cadmium was higher than for cobalt, however, the selectivity for both cations was low in this zeolite.

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Abstract  

The concentration of cobalt in 2 solid matrices was determined by neutron activation analysis (NAA) using standard solutions which were prepared by dissolving pure cobalt in nitric acid. The matrices assayed were a cobalt-aluminium wire and an iron foil and the respective Co concentrations found were 0.488% and 0.138%. Both solid materials can equally be used as standard references of cobalt in NAA. Subcadmium and epicadmium neutron fluxes in the reactor core were determined using Co–Al and Au–Al alloy wires. Very good agreement was obtained for all irradiation configurations of the target monitors cobalt and gold.

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Abstract  

A batch pertraction (liquid membrane extraction, MX) of cobalt has been studied, with industrial reagent LIX 64N and ABF (USSR) as a carrier. The influence of cobalt, reagents and acid concentration has been searched. The kinetic and hydrodynamic characteristics of the emulsion were optimized. In one batch pertraction process it is possible to reach 100-fold cobalt preconcentration with 93–98% yield from 1 dm3 sample volume.

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Abstract  

A radiochemical displacement method has been developed for the determination of nickel and cobalt based on the release of Zn-65 from labelled Zn(PAN)2 [1-(2-pyridylazo) 2-naphthol] complex in chloroform. The displacement behavior of Zn-65 by nickel and cobalt was studied in the pH range 5–7.5. The effect of various ions on the displacement was also examined. 2–20 g of nickel and cobalt was determined by the aid of calibration plots.

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Abstract  

A Mexican montmorillonite clay was intercalated on the one hand with aluminium or zirconium polyhydroxications, and on the other with two organic compounds. Radioactive cobalt was used to study the Co2+ sorption curves in the original and pillared clays. It was found that pillaring in general does not favour the diffusion of cobalt between the layers specially the organic pillared clays. In equilibrium, the cobalt retention reached the highest level, around 0.7 meq/g in the Zr pillared clay.

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Abstract  

The extraction of cobalt/II/ from ammonium chloride-ammonium hydroxide buffer solutions of pH 6.5 by 2,4-dihydroxyacetophenone thiosemicarbazone /DATS/ in n-butanol has been studied. Cobalt/II/ forms 11 complex /metal:reagent/ with DATS. Addition of pyridine enhances the extraction. The influence of metal concentration and the effect of diverse ions on the extraction of cobalt/II/ have been investigated.

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Abstract  

60Co was used as indicator for studies on the separation of cobalt with sodium alginate. Effect of eight experimental parameters (digestion time, digestion temperature, mode of separation, concentration of reagents, pH, order of heating, ammonia, mixing of reagents) on the precipitation and separation of cobalt alginate have been investigated.

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