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Abstract  

The contamination of leaves of some ornamental and fruit-tree plants (18 species), herbs (6) and early leafy vegetable (2) were assessed in the region of Bratislava and its vicinity through the first months after the Chernobyl accident. The levels of contamination showed local and temporal dependence. In October compared to its levels five months earlier, foliar contamination showed a relative 12- to 200-fold decrease of radioactivity. The effective half-life of the mixture of fission products in cumulative fallout on leaves of vegetation changed depending on time after the accident from 4 days (on day 10) to 150 days (after 2 months). The soluble fraction of radioactive contaminants on plant foliage ranged from 0.12 to 0.64.

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Abstract  

The total -radioactivity of dry, wet and cumulative fallout and the radioactivity of cow milk was measured in Bratislava in the first month after the Chernobyl accident. The obtained results are in good agreement with the results of the monitoring net in Slovakia.

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Anion exchange in mixed solvent systems

VII. Kinetics of anion exchange of some corrosion and fission products

Journal of Radioanalytical and Nuclear Chemistry
Author: V. Koprda

Abstract  

The diffusion of chlorocomplexes of some corrosion and fission products in anion exchange beads has been studied in mixed solvent media. The effects of variables on the kinetics of the exchange process by the batch and flow technique were examined. The strongly basic anion exchanger Dowex 2X8 in its Cl form was used in organic solvent—water—hydrochloric acid solutions. The dependence of the exchange rate on temperature, the viscosity of the solution, the mean resin particle diameter and the composition of the solution was studied. Film and particle diffusion coefficients were calculated from the experimental data. The results provide valuable data for the design of separation procedures.

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Abstract  

The diffusion of cobalt chloro complexes in anion-exchange beads has been studied in mixed solvent media. The effects of variables on the kinetics of the exchange process by the batch technique were examined. The strongly basic anion-exchanger Dowex 2X8 in its Cl form was used in ethyl alcohol-water-hydrochloric acid solutions. The rate laws were verified experimentally. The dependence of the exchange rate on the temperature, the viscosity of the solution, the mean resin particle diameter and the composition of the solution was studied.

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Abstract  

The possibilities of extraction-chromatographic separation of137mBa from137Cs in genetic succession were studied, using columns filled with support beads loaded with the extractant H+[)–(3)–1,2–B9C2H11]2Co, further referred to as dicarbolide-H+, in nitrobenzene. The dependence of the amount of separable activities on experimental conditions was established. Optimal conditions were selected for the separation process. The effects of isotopic and nonisotopic carriers of137mBa on the separation and the degree on saturation of extraction-chromatographic column with Ba2+ ions were evaluated. The effects of acidity of the elution solutions, of flow-through velocity, the amount of elution solution and the quality of carrier beads on the separation process were assessed. The extraction-chromatographic yield was calculated and the number of possible repeated elution cycles for137mBa with saline and some other eluents was determined.

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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 possibilities of radiostrontium extraction from milk after the isolation of radiocesium were investigated. The polyhedral complex of the type H+[(π-/3/-1,2-C2B9H11)2Co], further referred to as dicarbolide-H+, in nitrobenzene was used for the extraction. The increase of values and larger differentiation of distribution ratios in the extraction of ion associates of radionuclides were achieved by hydrophobizing with polyethyleneglycol (PEG). The changes of the distribution ratios of90Sr,89Sr and90Y with PEG concentration were studied, and ranges of the highest synergic effect, changing with different extraction agent concentrations in extraction from water solutions and a fresh milk were determined. The influence of milk dilution and nitric acid concentration upon the value of distribution ratio in radiostrontium extraction using dicarbolide-H+ and the optimum PEG concentration were investigated. Under suitably selected conditions of radiostrontium isolation, the distribution ratios of some potential contaminants were determined. The influence of nonisotopic carrier Ca2+ upon radiostrontium extraction was examined. The possibilities of purification of isolated radiostrontium using reextraction were investigated. A selective and quick analytical procedure was suggested for radiostrontium isolation after the separation of radiocesium from a mixture of fission and activated radionuclides in milk using extraction by dicarbolide-H+. The chemical yield is about 98% and90Sr is determined by liquid scintillation technique.

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Abstract  

Extraction by polyhedral complex compound of the formula H+ [(π-(3)-1,2-B9C2H11)2Co] further on referred to as dicarbolide-H+ and its chloro-derivate H+[B18C4H15Cl7Co] further on referred to as Cl-dicarbolide-H+ in nitrobenzene was used for the analysis of137Cs in urine and faeces after internal contamination. The dependence of distribution ratio on the acidity of analysed solutions was determined. The effect of urine dilution was assessed as well as the effect of various concentrations of the extraction agents on the distribution ratio of137Cs. The effect of phase ratio at the different concentrations of isotopic carrier was assessed, as well as the effect of potassium ions on the decrease of the distribution ratio at the extraction of137Cs by dicarbolide-H+ or its chloro-derivate. The possibility of isolation of137Cs by extraction and the isolation of137Cs by ion-exchange absorbents and by ammonium molybdophosphate was compared. The values of distribution coefficient were determined at various concentrations of nitric acid and the isotopic carrier. The dependence of coextraction of some activated radionuclides and fission products by dicarbolide-H+ on the nitric acid concentration in the solute was determined. The effect of mass of contaminated faeces on the value of the distribution ratio of137Cs by the extraction was evaluated. As a result, a suggestion was given for the rutine isolation procedure of137Cs extraction with dicarbolide-H+ from the excreta contaminated by a mixture of radionuclides.

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Abstract  

The possibility of use of a powder-like polymeric hydrogel of 2-hydroxyethyl methacrylate with 33 wt.% methacrylic acid as potential pharmaceutical adjuvant in the form of a composite powdered material, with silicone rubber in the form of matrices for transdermal therapeutic system has been studied. The effect of solvents and the content of composite hydrogel in matrices on the rate of permeation of an antianginic drug, radioactive labeled glycerol trinitrate (GTN) was evaluated. The results show that hydrogel copolymers are prospective adjuvants for transdermal therapeutic systems.

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Abstract  

The distribution of some radionuclides in the course of137Cs and90Sr extraction and scrubbing between organic and water phase was determined.137Cs and90Sr were isolated from the mixture of radionuclides in mineralized biological materials. Dicarbolide of cobalt i. e. 3,3′-commo-bis[undecahydro-1,2-dicarbo-3-closo-dodecaborate] was used as an extracting agent. Quantities of the extracted radionuclides were determined by gamma spectrometric technique. Single and repeated extraction of90Sr with 0.01M resp. 0.1M dicarbolide of cobalt in nitrobenzene and scrubbing of coextracted radionuclides by 0.5M HNO3 were studied. The extraction of90Sr was investigated from solutions of a hydrofobizing agent in the same way. Finally, the quantitative extraction of137Cs followed by the extraction of90Sr from mixtures of radionuclides in a mineralized biological material was studied. Extraction yields from dry and wet mineralizates of biological tissues, from urine and milk were compared. Suitable working conditions for the separation procedures were selected.

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