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- Author or Editor: T. Kimura x
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Abstract
Radiochemical studies of the coprecipitation behaviour of neptunium, plutonium, americium and curium with bismuth phosphate were carried out on the basis of the effect of the following variables: kinds of acid, acidity, and amounts of bismuth and coexisting other elements. Simultaneous determination of the actinide elements using the coprecipitation was accomplished by adding 1 mg of bismuth at 0.2M phosphoric acid and by direct measurement of alpha spectrum of the precipitates. The order of the coprecipitation yields of the elements was also discussed by the difference of both the oxidation states and sulfate complex formation.
Abstract
The reaction of neptunium, plutonium and americium with oxidizing or reducing agents in phosphoric acid solution has been studied to design a separation procedure of the actinide elements using coprecipitation with bismuth phosphate. In the presence of uranium, successive separation of neptunium, plutonium, americium and curium was accomplished by combining the coprecipitation and redox reaction of the elements. The coprecipitation behaviour of fission products during the course of sequential separation of the actinide elements on bismuth phosphate was also discussed.
Extraction chromatography in the TBP-HNO3 system
I. Extraction behaviour of Th(IV) and U(VI) with the TBP/XAD-4 resin
Abstract
The extraction behaviour of Th(IV) and U(VI) in extraction chromatography has been investigated on the basis of partition and infrared studies. The stationary phase was purified undiluted TBP supported on Amberlite XAD-4 and the mobile phase was nitric acid. The results have shown that the equilibria for the extraction of Th(IV) and U(VI) by the TBP/XAD-4 resin agreed very closely with those in solvent extraction.
Extraction chromatography in the TBP-HNO3 system
II. Characteristics of the TBP/XAD-4 resin on separation of actinide elements
Abstract
The characteristics of the TBP/XAD-4 resin on the separation of uranium, neptunium, plutonium, americium and fission products have been studied. The capacity of the TBP/XAD-4 column was compared with the maximum capacity determined by batch experiment using uranium. On the basis of distribution ratios of the actinide elements and fission products, the separation procedure of these elements was constructed by combining extraction chromatography in the TBP-HNO3 system and the redox reactions of the actinide elements.
Abstract
The coprecipitation behaviour of uranium or thorium with barium sulfate is investigated from the variation of yields with uranium or thorium concentration, acid and acidity, and amount of sodium and/or potassium sulfate. Uranium or thorium in quantities less than 1.5 mg is quantitatively coprecipitated with barium (5.9 mg) sulfate when using an optimum conditions. The chemical form of uranium in barium sulfate precipitates is discussed by determination of mole ratio of potassium to uranium.
Abstract
The destructive determination method of alpha emitters in various combustible solid materials has been investigated by a combination of acid digestion and coprecipitation with barium sulfate. It was consequently established that the method described in the paper may be applicable to determine alpha activities in the practical wastes.
Abstract
The search for the lowest energy conformation of complex {β-cyclodextrin (β-CD)+chlorambucil} were carried out by molecular mechanics method. Theoretical calculations of molecular interactions of complex were carried out using the molecular orbital method. The correlation between energy changes and molecular structures are discussed. The large interaction energies calculated by the molecular orbital method bears out the inclusion phenomenon.
Abstract
In order to elucidate the enthalpic stabilization of a 2-methyl-1,4-butanediol system (2M14BD) and a 3-chloro-1,2-propanediol (3C12PDO) system by mixing of each (R)- and (S)-enantiomers, three-body interaction energies are obtained by PW91/6-311G** and MP2/6-311G** level calculations. The differences between homochiral interactions and heterochiral interactions in a 3C12PDO system are found. On the other hand, in 2M14BD systems, very slight differences can be observed between the three-body interaction energies of the three ternary systems. Further, the relationship between excess enthalpies and chiral interactions is discussed.
Extraction chromatography in the DHDECMP—HNO3 system
I. Extraction behaviour of Ce(III) and Am(III) with the DHDECMP/XAD-4 resin
Abstract
The extraction behaviour of Ce(III) and Am(III) in extraction chromatography has been investigated on the basis of partition and infrared studies. The stationary phase was purified undiluted DHDECMP supported on Amberlite XAD-4 and the mobile phase was nitric acid. The results have shown that the equilibria for the extraction of Ce(III) and Am(III) by the DHDECMP/XAD-4 resin agreed very closely with those in solvent extraction.
Abstract
An organic resin impregnated with DHDECMP was prepared for extraction chromatography and used for separation of the actinide elements. A known amount of inert support, Amberlite XAD-4, was contacted with a given amount of the extractant and water. By contacting the three phases for several hours at room temperature, the resin can be modified regardless of its mesh size. It is loaded with (1.13±0.03) g of DHDECMP per 1 g of the support. A given amount of the modified resin was contacted 50 times with fresh 3M nitric acid solution to remove the loosely bound extractant from the support. its amount was less than 1 weight%. As an application,241Am was recovered from 3.5M nitric acid waste solution on a column of the modified resin. Decontamination factor for the effluent was 105, while approximately 113 mg of241Am was obtained in 0.3M nitric acid eluting solution with 95% efficiency.
