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Abstract  

Solvent extraction of rhodium, ruthenium and iridium with di(2-ethylhexyl)phosphoric acid (HDEHP) has been investigated. Under the conditions [Cl–1]=0.20M, [(HDEHP)2]=0.30M, pH 4.05, phase contact time 1 minutes, Rh(III) is extracted 90.7%, Ru(III) and Ir(III) 20.0% and 11.5%, respectively, at phase ratio 11. The distribution ratio of rhodium is proportional to [(HDEHP)2]3 for a freshly prepared aqueous phase with low chloride concentration but might drop to [(HDEHP)2]1to2 for an aqueous phase high in chloride concentration and after standing. The spectroscopic studies indicate that the extracted compound of rhodium is Rh(H2O)6–xClx[H(DEHP)2]3–x (x=0, 1, 2).

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Abstract  

Solvent extraction of rhodium, ruthenium, and iridium with HDEHP from thioureachloride media was investigated. Under the conditions ([Cl]=0.50 M, [HDEHP]=1.0M, [SC(NH2)2]=0.50M, pH=4.50, phase contact time 1 min), Rh(III) is extracted 88.3%, Ru(III) and Ir(III) 40.8% and 28.5% respectively at phase ratio 11. The formation of rhodium-thiourea complexes in aqueous solutions, even at 5M chloride concentration, with the possible composition Rh[SC (NH2)2]6 3+ is confirmed by the observed molar ratio of thiourea to rhodium and UV-spectra.

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Abstract  

Mono- and divalent cations of trace elements were not retained at all on a cation-exchange column in the presence of a colloid. When the colloid was dissolved, cations sorbed and eluted from the column in a normal way.

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Abstract  

The multistage solvent extraction system SISAK is described. The system is used for online studies of nuclides with half-lives down to 1 s. Some of the chemical separation procedures are presented, and a survey is given on the results obtained so far. The possiblity to gain access to nuclides with even shorter half-lives is also discussed.

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Abstract  

Off-line and on-line studies have been performed with radioactive tracers of various elements to develop a chemical separation procedure for bohrium (element 107). The proposed procedure is intended for use in the fast solvent extraction system SISAK. The homologs technetium and rhenium were used to model the chemical behavior of bohrium. The results show that high decontamination factors can be obtained for technetium and rhenium with respect to unwanted contaminants like trivalent actinides, polonium and the Group 5 elements.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Alstad, G. Skarnemark, F. Haberberger, G. Herrmann, A. Nähler, M. Pense-Maskow, and N. Trautmann

Abstract  

The H-0.3 liquid-liquid centrifuge applied for rapid and efficient separation of two liquid phases, and the HG-0.1 gas-liquid centrifuge used to separate the gas phase stemming from a gas jet transportation system and the liquid phase, have been further improved. New centrifuges have been produced of PEEK, a plastic material, which makes them resistant to most aqueous and organic solutions. The performance with respect to time behavior and phase purity is comparable to the titanium centrifuges used so far. The H-0.3 centrifuge has been applied to solvent extraction studies of Zr, Nb, Mo, Hf, Ta, W and Pa from HF solutions into tri-n-octylamine.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: B. Wierczinski, J. Alstad, K. Eberhardt, J. Kratz, R. Malmbeck, M. Mendel, A. Nähler, J. Omtvedt, G. Skarnemark, N. Trautmann, and N. Wiehl

Abstract  

Fast solvent extraction is a chemical separation method, which can be applied to study exotic nuclides. Since about 1970 the SISAK technique, which is an on-line method based on multi-stage solvent extraction separations, has been successfully used to investigate the nuclear properties of β-decaying nuclides with half-lives down to about one second. During the last decade it has become possible to produce transactinide elements in high enough yields to investigate their chemical properties on a one-atom-at-a-time scale. For this purpose it was necessary to improve and change the detection part of the SISAK system in order to be capable to detect spontaneously fissioning and α-decaying nuclides in a flowing organic solution. This technique is based on liquid scintillation counting with pulse-shape discrimination and pile-up rejection

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Journal of Radioanalytical and Nuclear Chemistry
Authors: B. Wierczinski, K. Gregorich, B. Kadkhodayan, D. Lee, L. Beauvais, M. Hendricks, C. Kacher, M. Lane, D. Keeney-Shaughnessy, N. Stoyer, D. Strellis, E. Sylwester, P. Wilk, D. Hoffman, R. Malmbeck, G. Skarnemark, J. Alstad, J. Omtvedt, K. Eberhardt, M. Mendel, A. Nähler, and N. Trautmann

Abstract  

Subsecond 224 Pa (T 1/2 = 0.85 s) was produced via the 209 Bi(18 O,3n)224 Pa reaction at the 88 inch cyclotron at the Lawrence Berkeley National Laboratory. After production it was transported via a gas-jet system to the centrifuge system SISAK 3. Following on-line extraction with trioctylamine/scintillation solutions from 1M lactic acid, 224 Pa was detected applying on-line -liquid scintillation counting. Unambiguous identification was achieved using time-correlated --decay chain analysis. This constitutes the first chemical on-line separation and detection of a subsecond -decaying nuclide, 0.85-s 224 Pa with the fast extraction system SISAK 3.

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