Synergic extraction of trivalent Eu, Gd and Am from aqueous perchlorate medium has been studied using mixtures of thenoyltrifluoroacetone (HTTA) and 15-crown-5 or 18-crown-6 (CE) in chloroform at (25±1) °C. Slope analysis of the extraction results indicated a general formula of M(TTA)3·(CE)2 for the extracted species. The stability order took the sequence Eu(TTA)3·(CE)2>Am(TTA)3)·(CE)2>>Gd(TTA)3·(CE)2 with 15C5 and Am(TTA)3·(CE)2>Eu(TTA)3·(CE)2>Gd(TTA)3·(CE)2 with 18C6. The synergic factors, extracton constants and formation constants of the extracted species were determined and discussed in terms of the correspondence between cavity size of the crown ethers and ionic crystal radii.
Authors:H. Yang, E. Lee, J. Lim, D. Chung, and K. Kim
The extraction of Am(III) and Eu(III) using a γ-pre-irradiated N,N′-dimethyl-N,N′-dibutyltetradecyl malonamide (DMDBTDMA)
modified with N,N′-dihexyloctanamide (DHOA) in n-dodecane (NDD) at 4.5M HNO3 has been studied as a function of the absorbed dose up to 2×106 Gray. The distribution ratios of Am(III) and Eu(III) were almost constant until a dose of 1×105 Gray and then they decreased gradually up to a dose of 2×106 Gray. The decrease of the distribution ratios of Am(III) and Eu(III) are due to the decreasing concentration of the DMDBTDMA
by a γ-pre-irradiation and these results were supported by a determination of the DMDBTDMA concentration with a gas chromatography
method. The distribution ratios of Am(III), Eu(III), Ce, Nd and Y with γ-pre-irradiated (DMDBTDMA-DHOA)/NDD have also been
studied as a function of the nitric acid concentration and the extraction temperature.
Authors:L. E. Muresan, E.-J. Popovici, E. Bica, A. I. Cadis, I. Perhaita, and L. Barbu Tudoran
-pyrolysis [ 16 ]. This paper is focuses on the preparation of some europium-doped yttrium aluminate YAG:Eu samples, using the wet-chemical synthesis route (precipitation) via the simultaneous addition of reactants technique, WCS-SimAdd [ 17 , 18 ].
The paper describes the production of a tracer packet of heavier rare earth elements containing carrier-free radionuclides
of 153,155Tb, 153,155,157Dy, 159Ho, 159,161Er, 161Tm produced by medium energy 7Li and 12C irradiation on an europium oxide target and the subsequent separation of bulk europium from the carrier-free products.
The radioactive tracer method was used to investigate the adsorption of iodide and europium ions from aqueous solution on dried isoelectric precipitates of silver sulfide, silver iodide and silver bromide. The relationship between the amount of iodide ions adsorbed on Ag2S and the iodide ion and HNO3 concentrations in the solution was determined. It was shown that the iodide ions adsorbed on Ag2S could be desorbed with sulfide ions. Using Ag2S, AgI and AgBr precipitates, a relationship between the europium ion adsorption and Eu(NO3)3, H2S, NaI, NaBr and NaCl concentration in solution was established. The adsorption of europium ions was also assessed in respect to the presence of lanthanum and barium ions. For adsorption measurement iodide and europium ions were labeled with their radioactive isotopes and the amounts adsorbed were determined from the measured radioactivities of the precipitates after reaching the equilibrium between the solid phase and the solution.
Authors:M. Batista, M. Ginani, D. Melo, and A. Oliveira
ZnS(1-x)MSx(x=0.01 and M=Mn2+, Cu2+ and Eu2+) compounds have been obtained by precipitation from homogeneous solutions of zinc, copper, manganese and europium salts,
with S2- as the precipitating anion, formed by the decomposition of thioacetamide. The thermal study of the milled zinc acetate, thioacetamide,
copper acetate, manganese acetate and europium nitrate, respectively, was studied for thermal analyis TG/DSC. XRD respect
exhibits a zinc blend crystal structure.
Authors:M. Weigl, U. Müllich, A Geist, K. Gompper, T. Zevaco, and H. Stephan
2,6-di(3-alkyl-1,2,4-oxadiazol-5-yl)pyridines, 2,6-di(5-alkyl-1,3,4-oxadiazol-2-yl)pyridines, and 2,6-di(5-alkyl-1,2,4-oxadiazol-3-yl)pyridines were synthesized and tested for their americium(III)-europium(III) selectivity by liquid-liquid extraction. 0.02M solutions of the compounds extract americium(III) 2-bromohexanoates as monosolvates, AmA3B, from solutions of pH 2, with an americium(III)-europium(III) separation factor of up to 23. Decreasing the alkyl chain length (butyl < ethyl < methyl) or the polarity of the diluent (chlorobenzene < toluene < tert.-butyl benzene) increased both americium(III) distribution ratio and americium(III)-europium(III) separation factor.
Eu/III/ and Ce/III/ are adsorbed on controlled pore glass from neutral and basic solutions. The experiments have been carried out using 10–5M solutions of chlorides. For 0.1 M NaCl as a supporting electrolyte very low adsorption is observed below pH 6 and above pH 8 the adsorption curve has a plateau corresponding to over 90% of europium /or cerium/ adsorbed. At lower NaCl concentrations the above pH values shift towards lower values. Europium adsorbs considerably better than cerium and the best selectivity is observed at pH=7.
Authors:P. Vañura, V. Jedináková, and I. Juklíková
The extraction of144Ce and152,154Eu microamounts by nitrobenzene solutions of bis-1,2-dicarbollylcobaltate in the presence of 18-crown-6 from aqueous solutions of nitric acid has been investigated. The protonisation constants of 18-crown-6 in water and in nitrobenzene were determined and the corresponding equilibrium constants for cerium and europium extraction were evaluated.
The kinetics of homogeneous electron exchange Eu3+/Eu2+ has been investigated in 1M HClO4, water+dimethylformamide (DMF) mixed solvent by using labeled europium. Non-monotonic variations of the electron exchange rate constants as a function of the solvent composition was observed.