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  • Author or Editor: R. Caletka x
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Abstract  

The adsorption behaviour of zirconium and niobium on silica gel from hydrochloric acid solutions was studied by batch equilibrations and passage through columns. On the basis of this, new methods are suggested for the separation and purification of95Zr and95Nb in hydrochloric acid and hydrochloric acid—methanol solutions. The methods are comparatively simple and rapid, and both zirconium and niobium can be obtained in a radiochemically pure state.

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Abstract  

The possible use of titanium(IV) hexacyanoferrate(II) as a cation exchanger increased the interest in the preparation of materials with favourable ion exchange capacities and mechanical strength to be used in the columns. A new method of preparation has been developed, which is based on the treatment of spherical particles of titanium hydroxide gel with acidic solutions of potassium hexacyanoferrate(II). Materials of variable composition were obtained. The maximum value for the retention capacity for cesium was found to be of 2.6 meq. Cs per gram of ion exchanger.

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Abstract  

The paper deals with the study of inorganic acid uptake on hydrogels of titanium, zirconium, and tin hydroxides prepared by the sol-gel method in the form of regular spherical particles. The aim of the work was the determination of the basic conditions for the preparation of inorganic ion exchangers by means of the conversion of the hydroxide gel. The results obtained prove that the exchange of hydroxide groups of the gel phase for the respective anions plays the decisive role in the uptake on zirconium hydroxide. With similar titanium and tin compounds, the main process affecting the uptake is the formation of adsorption compounds and the free diffusion of the electrolyte into the gel phase. The possibilities of the application of the sol-gel method for the preparation of inorganic sorbents are discussed.

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Abstract  

In the search for an efficient method of recovery of germanium from concentrated mineral acid solutions, silica gel has been found to be a selective adsorbent for this element. A method of quantitative separation of gallium from germanium is described which can be applied for the preparation of68Ge−68Ga isotope generator and for the isolation of68Ge from a zinc target. The applicability of the present method was also studied for the separation of a gertarget. The applicability of the present method was also studied for the separation of a germanium matrix in determining admixtures in semiconductor germanium samples by activation analysis.

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Abstract  

The use of nuclide95Zr as radiotracer is often unfavourably influenced by the continuous accumulation of the radioactive daughter nuclide95Nb. The present paper gives a method showing how the daughter radioactivity can influence the value of the distribution coefficient of zirconium calculated from radioactivity measurements. A simple method of continuous purification of95Zr, which yields a product of the required degree of purity, is also described.

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Abstract  

Distribution ratios for As(V), Fe(III), Sb(V), Sc, Sn(IV), Mo, W, Tc(VII) and Re(VII) in the system Dowex-1X8 and 0.1–11.5M HCl, and Dowex-1X8 and the mixture of HF and HCl with HF concentrations varying from 0.1M to 20M and HCl concentrations from 0.1 to 10M have been measured. The distribution ratios for mixed solutions are presented in form of adsorption contour plots. The connection between the possible composition of the adsorbable complexes and the character of the respective contour plots is discussed.

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Abstract  

The behaviour of the elements As, Ba, Cr, Fe, Eu, Hf, La, Mo, Nb, Pa, Re, Sb, Sc, Sn, Ta, Tc, W, and Zr on Dowex-1X8 in 0.1 to 29.5M HF and mixed solutions of HF and NH4F of different concentration combinations varying for both reagents from 0.1 to 10M has been studied. The influence of the ionic form of Dowex-1 on the distribution of elements has also been examined. The distribution ratio for the mixed solutions are given in form of adsorption contour lines.

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Abstract  

Three different methods for pre-irradiation separation of the tantalum matrix combined with preconcentration of trace elements for NAA were developed. They involve selective extraction of tantalum with diantipyrylmethane, and anion- and cation-exchange from hydrofluoric acid medium. The role of the blank as the limiting factor for limits of detection and accuracy was one of the main aspects of this investigation. A conventional radiochemical NAA based on post-irradiation separation of the matrix radionuclides was also applied. The trace elements considered were Ag, Ba, Ce, Co, Cr, Cu, Eu, Hf, K, La, Mn, Mo, Na, Rb, Re, Sc, W, Y, Zn, Zr. The methods were used for the analysis of tantalum materials of different purity grades. The advantages and disadvantages of each technique are discussed and the achievable limits of detection are given.

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Abstract  

A radiochemical neutron activation technique for the detemination of 19 elements in high purity tungsten has been developed. It is based on extraction with diantipyrylmethane (for tantalum and antimony), substoichiometric extraction of molybdophosphate (for phosphorus) and anion-exchange chromatography (other elements) in hydrofluoric acid medium. The results obtained and achievable limits of detection are given. The effects of self-shielding and nuclear interfering reactions are discussed.

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Abstract  

Anion-exchange data have been obtained for the elements As, Hf, Mo, Nb, Pa, Re, Sb, Sn, Ta, Tc, W, and Zr in 0.1 to 10M H2SO4 and in HF–H2SO4 mixtures of combination extending from 0.1 to 10M HF and from 0.1 to 10M H2SO4. The distribution ratios for mixed solutions are presented in form of adsorption contour lines.

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