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  • Author or Editor: J. Cibulková x
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Abstract  

Previously it was found that in the extraction separation on lanthanides and americium from acidic nitrate solutions of nuclear fission products, benzyldimethyldodecylammonium nitrate gives high values of separation coefficients. The change in the extraction capacity of this agent and its solutions in benzene in the extraction of Eu(III) and Am(III) was investigated as a function of the adsorbed dose of ionizing radiation. The slight reduction in the extraction of both metals is caused mainly by the radiolysis products of nitric acid in the organic phase that enter into secondary reactions with both the solvent and the extractant. Comparison of the radiation stability of benzyldimethyldodecylammonium nitrate systems with tertiary amines show that the changes in distribution coefficients in the range of investigated absorbed doses are significantly lower in the former case. The investigated system may be characterized as radiation stable up to about 100 kGy even in the presence of nitric acid.

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Abstract  

The effect of gamma irradiation on benzene solutions of benzyldibutylamine with cetyl alcohol used for the extraction of europium and americium from nitrate solutions was investigated. The dependence of the distribution coefficient on the dose absorbed either by the whole system or some efficient component was measured. Nitric acid present during irradiation significantly lowers the radiation stability, while benzyldibutylamine and cetyl alcohol appear to be radiostable components. Up to tens of kGy's—the doses expected in an extraction process from highly active solutions—the system seems to be quite stable.

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Abstract  

The radiation stability was investigated of organic phases containing tertiary benzyldialkylamines and quaternary benzyltrialkylammonium salts which are sultable for the separation of lanthanides and americium from irradiated nuclear fuel. Attention was paid to changes of the extraction properties in Eu(III) and Am(III) extraction. The influence of the individual components forming the organic phase (extractant, solvent, solubilizer and nitric acid) on the decrease of the extraction capacity of the organic phase after irradiation is discussed. The greatest changes in the distribution coefficients DEu and DAm after irradiation were shown for extraction in the presence of nitric acid. As regards the absorbed dose, these systems can be considered as stable in comparison with organophosphorus extractans.

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Abstract  

Benzyldimethyldodecylammonium nitrate and benzyltrioctylammonium nitrate were used for the extraction of Am(III) from aqueous nitrate solutions. The dependence of the extraction performance for Am(III) on the concentration of nitric acid, the kind and concentration of salting-out agents in the aqueous phase, and the kind of solvent was investigated. Americium is extracted by the above quarternary salts as a R4NAm(NO3)4 associate. The extraction of Am(III) is compared with the extraction of lanthanides. The high differences in the distribution coefficients for lanthanides and americium can be utilized for the separation of lanthanides and americium.

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Summary The antioxidant activity of selected N,N'-substituted p-phenylenediamines derived from 6PPD in polyisoprene matrix has been studied by differential scanning calorimetry (DSC) under non-isothermal conditions. The kinetic parameters describing temperature dependence of induction period have been obtained. Protection factors and antioxidant effectiveness have been calculated to characterize the stabilizing effect of the antioxidants under study. Using both criteria, the highest antioxidant activity has been observed in the case of Dusantox L, which is a mixture of 6PPD and its p-kumyl derivative. Its high antioxidant efficiency can be explained by the synergistic effect of 6PPD and its p-kumyl derivative. The lowest antioxidant efficiency of o-kumylderivative of 6PPD is probably caused by the sterical effect of the bulky kumyl group.

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