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  • Author or Editor: N. Souka x
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Abstract  

A systematic investigation on99mTc and99Mo extraction by (C6 H5)4As+ from HCl, HBr, HNO3, and H2SO4 solutions has been undertaken. Technecium extraction was found to attain very high values at low acid concentrations, while molybdenum has negligible extraction coefficients. Consequently, at low acidities, Tc could be separated from irradiated Mo with very high selectivity. TcO 4 distribution coefficient was found to depend, however, on the nature and concentration of competing anions. For the same anion concentration, the selectivity of Tc extraction takes the sequence SO 4 2− >Cl>Br>NO 3 . Experimental results enabled a calculation of stability constant of (C6 H5)4 AsTcO4. Extraction data were used to identify parameters for a99mTc generator.

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Abstract  

The adsorption behaviours of trivalent and pentavalent antimony on zirconium phosphate from hydrochloric acid solution and hydrochloric acid alcoholic solutions were investigated. The substitution of increasing amounts of water by alcohols was found to decrease the uptake of Sb (III) and increase that of Sb (V). Results were discussed and column separations of the two oxidation states were carried out.

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Abstract  

Studies on (C6H5)4 AsCl extraction of233Pa,233U,234Th,95Zr,95Nb and Eu from hydrochloric acid solutions, oxalic acid solutions, as well as binary mixtures, of the two acids have been undertaken. Studies from HCl solutions indicated that tetraphenylarsonium is an efficient solvent for Pa, U and Nb while Zr, Eu, Th and Np have rather low extraction coefficients. Studies from H2C2O4 indicated again negligible extraction for Eu, Np and Zr, while Pa, U and Nb have considerable distribution coefficients characterized by certain maxima. Extraction data from binary mixtures of HCl and H2C2O4 suggest possible purification procedures for the investigated elements.

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Abstract  

The squarate complexes of Eu3+, Tb3+ and Tm3+ in aqueous solutions of 0.05M, 0.075M and 0.1M ionic strength are studied using the solvent extraction method. Effects of changes in the ionic strength on the stability constants of the complexes formed are discussed.

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Abstract  

Sorption of Th, Pa, U, Np and Pu on silica gel from HNO3, HCl and HCl−ROH solutions was investigated. Equilibrium studies indicated sorption behaviour to vary greatly with the acid used. In mixtures of HCl with different alcohols, distribution coefficints were found to depend on alcohol percentage as well as on acidity. Results were discussed and conditions for possible separations were indicated.

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Abstract  

The adsorption behaviour of thorium, protactinium, uranium, neptonium and plutonium on zirconium phosphate from nitric acid and ammonium nitrate solutions was investigated. Partition data from the mentioned media together with that from chloride solutions were used to calculate formation constants for the concerned elements in the range of Cl and NO 3 activities <1M. Obtained β values were compared with those reported in the literature and indicated reasonable agreement.

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Abstract  

Studies on the extraction of thorium, protactinium, uranium and neptunium from H2SO4 solutions by TLA indicated that these elements have low distribution coefficients (<0.1) at high acid concentrations. Additions of HCl or HBr to H2SO4 solutions enhances appreciably the extraction of the mentioned elements. A systematic investigation on the effect of halide concentration and solvetn concentration helped in explaining the observed enhancement as well as identifying the extracted complexes.

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Abstract  

The study includes the effect of absorbed dose on the absorption spectra of thoron solutions at different pHs and different concentrations. The effect of absorbed dose on the linear response limit and the decolouration yield (G-value) were determined. These results were used in determining the dosimetric characteristics of the dye solutions.Some of the investigations were undertaken in presence of varying concentrations of ethyl alcohol. The results helped in recommending a decolouration mechanism, and in calculating the specific bimolecular rate constant for reaction of the dye with OH radicals.

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Abstract  

This work is an investigation of the radiation stability of thoron-uranium complex. It deals mainly with the effect of absorbed dose on the absorption spectra of the complex at different complex concentrations. The radiolysis of the complex, was also investigated in presence of varying concentrations of ethanol and methanol. The decrease in absorbance at the characteristic peak as a function of absorbed dose, complex concentration, and alcohol concentration was used to calculate the G-value and the specific rate of bimolecular interaction of the complex molecule with water radiolysis products. The radiolysis mechanism was discussed in the light of the results.

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Abstract  

The extraction of Eu(III) by dinonylnaphthalenesulfonic acid (HDNNS) in benzene from nitrate and perchlorate solutions has been investigated. For nitrate solutions the ionic strength of the aqueous phase was kept constant at 0.1M using NaNO3–HNO3 mixtures. The Eu distribution was measured at different temperatures. The following stoichiometric formulae for the Eu species in benzene were derived: Eu(NO3) (Hn–1 (DNNS)n)2 and Eu(Hn–1 (DNNS)n)3, from the nitrate and perchlorate medium respectively (n being a small number, e.g. 1, 2 or 3). The equilibrium constants were calculated and the thermodynamic parameters of the system were determined. When adding dibenzo-24-crown-8, dicyclohexyl-18-crown-6 or trioctylphosphine oxide, no synergism, but rather antagonism was observed.

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