[en] Personnel conducted testing to determine the apparent solubility of benzene in potassium tetraphenylborate (KTPB) slurries. The lack of benzene vapor pressure suppression in these tests indicate that for a 6.5 wt percent solids KTPB slurry in 4.65 M Na+ salt solution at approximately 25 degrees Celsius, no significant difference exists between the solubility of benzene in the slurry and the solubility of benzene in salt solution without KTPB solids. The work showed similar results in slurry with 6,000 mg/L sludge and 2,000 mg/L monosodium titanate added. Slurries containing tetraphenylborate decomposition intermediates (i.e., 4,200 mg/L triphenylboron (3PB), 510 mg/L diphenylborinic acid (2PB) and 1,500 mg/L phenylboric acid (1PB) or 100 mg/L tri-n-butylphosphate (TBP)) also showed no significant difference in benzene solubility form filtrate containing no KTPB solids. Slurry containing 2,000 mg/L Surfynol 420 did exhibit significant additional benzene solubility, as did irradiated slurries. The vapor pressure depression in the irradiated slurries presumably results from dissolution of biphenyl and other tetraphenylborate irradiation products in the benzene

[en] Ion exchange systems found wide application in radiochemical separation of many radiotracers. In nuclear technology, ion exchange resins are usually used for purification of many of the fission products radio-nuclides as well as actinides and lanthanides . To achieve a good separation conditions, selectivity of the ion exchange system for the ion to be isolated is required. one approach to improve such selectivity is to manipulate the ionic form of the elements to be separated. This modification can be reached by the presence of certain complexing ligands. In this concern, the cation exchange behaviour of many metal ions was investigated in the presence of negatively charged ligands. On the other hand, the effect of neutral ligands on the ion exchange processes with organic resins has, so far, received little attention. Therefore, it was found of interest to add more information on the cation exchange behaviour of some radiotracer in the system comprising , the cation exchanger dowex 50 W -X8, the neutral ligand; benzylamine and different mineral acids

[en] A new cycloalkane-monoamide with high distribution ratio of U(VI) was obtained by tuning the ring size of the cycloalkane to give the highest basicity of oxygen donor atom of functional group; C=O of the monoamide, and by increasing lipophilicity of the amide molecule through appending long alkyl chain to the position with the least steric effect on metal bonding. Hence the 3.5-octyl-N-octyl-valerolactam designed revealed the highest extractability toward U(VI) without the third phase formation. In the study on a bidentate ligand-lanthanides(III): Ln(III) extraction system, to clarify the principal parameters of controlling distribution behaviour of Ln(III), the structural study by EXAFS was carried out, and the structure of the Ln(III)-ligand complex for several di-phosphine dioxides was discussed in relation to the number of the ligand coordinating to the Ln(III) ions, the basicity of the donor oxygen, and the nature of the metal-ligand bond. (author)

[en] In model experiments with W, Hf, Th, and U radionuclides, a chemical system was developed for the separation of seaborgium from element 104 and heavy actinides, i.e., cation exchange on Dowex 50X8 from solutions containing 0.1-1.0 M HCl and 0.5-2.0 vol% H₂O₂. The system should be suitable for fast online experiments if seaborgium exhibits a non-uranium-like behaviour. Adding hydrogen peroxide to mixed HCl/HF solutions suppresses the partial sorption of W and, presumably seaborgium, on the cation exchanger. This way, the elution volume can be minimized. Prospects for anion exchange separations of group 6 from group 4 elements are also briefly discussed. (orig.)

[en] The ion transfer of UO₂²⁺ ion across an aqueous(w)/nitrobenzene(NB) interface was investigated by ion-transfer polarography using an aqueous electrolyte dropping electrode. It was found that the transfer of UO₂²⁺ from w to NB was facilitated by bis(diphenylphosphoryl)methane (BDPPM), and that the transfer reaction had irreversible characteristics. A potential generated at the UO₂²⁺ ion-selective electrode, which was prepared while referring to ion transfer data, revealed a reversible Nernstian response against the concentration of the UO₂²⁺ ion in an aqueous sample solution. The irreversible nature of the UO₂²⁺ transfer observed in the polarogram resulted from such slow processes involved in the ion transfer reaction as the adsorption/desorption of BDPPM or the UO₂²⁺-BDPPM complex at the w/NB interface. The feasibility of the electrolytic separation of uranium from neptunium and plutonium on the basis of a selective ion-transfer reaction is discussed. (author)

[en] The reproducibility, the small scale as well as the large scale variability of ¹³⁷Cs extracted sequentially from the soil by using a modified Tessier procedure was investigated at several grassland sites in Bavaria/Germany and in the Chernobyl area. Because undisturbed grassland soils are never homogeneous with respect to their soil properties, all sequential extractions at the German sites were carried out at each plot separately for different soil layers (e.g., 0-2, 2-5, 5-10, 10-15, 15-20 and 20-30 cm). The results show that the coefficients of variation (CV) for the reproducibility of the extraction procedure for ¹³⁷Cs was (with some exceptions) around 10-20% for all fractions. For the small scale variability of ¹³⁷Cs (samples within an area of 10 x 10 m²) the values for the CV were (again with a few exceptions) in the same range. Compared to that, the large scale variability of extractable ¹³⁷Cs (random soil samples within an area of 100 x 200 km²) was higher for all fractions, even though only moderately. The implications of these results with respect to a sampling design are discussed. (author)

[en] Extraction of As(III) and As(V) from sulphuric acids solutions of H₂SO₄ of various concentration (50-200 g/dm³ with Cyanex 923 dissolved in Exxsol 220/230) was studied and compared. Cyanex 923 can be considered as an effective arsenic extractant. Sulphuric acid is co-extracted. Extraction both of As(III) and As(V) occurs quickly and the equilibrium is obtained after 5 minutes. The isotherms of As(III) and As(V) extraction at various sulphuric acid concentrations were determined and used to model the multistage countercurrent process. Arsenic can be stripped with water. (author)

[en] 4-Octylphenylamine, decyl isonicotiniate, decyl nicotiniate, decyl 2-hydroxyethyl sulphide and its analog with partly fluorinated alkyl group were used for palladium(II) extraction from 3M HCl. The adsorption of these compounds at toluene/HCl solution was also studied and interpreted. 4-Octylphenylamine adsorbs at the hydrocarbon/HCl solution at much lower concentration range than other extractants and can be used as a phase transfer catalyst. The addition of 4-octylphenylamine increases the extraction rate with esters of pyridine carboxylic acids and decreases the time needed to obtain the equilibrium of extraction. (author)

[en] The increasing need to uranium and thorium for nuclear energy programmes has stimulated the development of many methods for their separation both in large amount and in trace. Of these methods, precipitation, ion exchange, adsorption and solvent extraction are the most important. These techniques, though have found much application for the separation of uranium , they their limitations and new methods are, therefore, required for the separation of these elements from aqueous solutions especially when they are present in low concentrations . For this reason, the relatively new techniques: foam separations have been investigated. In foam separation processes, separation occurs by virtue of differences in the surface activity of the substances to be removed. Until about two decades ago, only naturally surface - active substances could be separated by foaming. Metal ions are not naturally surface-active but, lately, it was discovered that foaming could also concentrate inorganic solutions

[en] Procedures for the separation and determination of ⁹⁰Sr in liquid samples, with cation and anion exchangers have been described. Strontium, yttrium and other cations bind to the cation exchanger and are eluted from the column by means of nitric acid. Separation of yttrium and strontium from other cations is carried out on columns filled with strong base anion exchangers in nitrate form with alcoholic solutions of nitric acid. This separation method enables the determination of ⁹⁰Sr through yttrium on a low-level gas flow α, β-counter, as well as through strontium on a low-level liquid scintillation counter by means of Cherenkov counting. Such procedures have been tested by the determination of ⁹⁰Sr in water, wine, medium radioactive liquid waste samples, milk and clover samples. For comparison, the determination has also been carried out by the standard method. It has been showed that the developed procedures might produce a high efficiency in strontium separation and a satisfactory accuracy of determination. (author)