The153/151Eu isotope separation factor (q) for the Eu(II)/Eu(III) chemical exchange in the liquid-liquid extraction system, containing Eu (III) in di (2-ethylhexyl) phosphoric acid (HDEHP) and Eu(II) in water acidified with hydrochloric acid, was found to be 0.9993±0.0002 (2) for the single stage. Some theoretical aspects of separation of the Eu isotopes are discussed. The decisive role of the electron exchange reaction and complexation by the counter-ion in the aqueous phase is emphasized.
Authors:Yanxia Geng, Zhan Li, Duoqiang Pan, and Wangsuo Wu
For the selective extraction of Am(III) and Eu(III), quadridentate divalent phenolic Schiff bases-bis-salicylaldehyde ethylenediamine
(H2salen) was investigated as a kind of extractant. The influences of alkaline cation, inorganic anion, ionic strength, pH and
the concentration of H2salen on the distribution ratio of Am(III) and Eu(III) were investigated in detail. As a result, Am(III) and Eu(III) made
anionic 1:1 complexes with the ligand (H2salen) and could be extracted into nitrobenzene as ion-pairs with a suitable monovalent counter anion in the aqueous solution,
the extracted species were possibly of the type Am(H2salen) Eu(salen)Cl and Eu(H2salen)Cl3, respectively. The extractability of Eu(III) was significantly stronger than that of Am(III) and the maximum separation factor,
SF(Am/Eu), was 96 at pH 4.0. The results indicated that H2salen had good selectivity for Am(III) and Eu(III).
Authors:Y. Wang, Q. Fan, P. Li, X. Zheng, J. Xu, Y. Jin, and W. Wu
The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated
under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic
strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III)
uptake on soil, however at low pH values, the influence of anions was following the order: Cl− ≈ NO3− > ClO4−. In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7,
the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes
in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed
outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8.
Distribution of Hg2+, Co2+, Sc3+ and Eu3+ between the cation exchanger Dowex-50X8, [H+] (100–200 mesh), and 1M HNO3 solution containing different benzylamine (BA) concentrations has been studied. The distribution coefficient, D, for Co2+, Sc3+ and Eu3+ is very small and does not vary seriously with the BA concentration. It is also found that Hg2+ is highly taken by the resin from the media studied. In this respect, D increases with increasing BA concentration to reach
a maximum at 0.5% BA in 1M HNO3. This behaviour is explained by the exchange of molecular species between the cation exchanger and the aqueous phase. Based
on the results, a radiochemical separation procedure for the selective isolation of Hg2+ from Co2+, Sc3+ and Eu3+ has been developed. The radiochemical purity is not less than 99.8% and the chemical yield more than 95% for the separated203Hg.
A radiotracer method, initially developed to analyze migration from retail plastic food packaging into food simulants, has been developed to assess the measurement of inorganic contaminants migrating from recycled paper and board into real food. This new radiotracer method has been applied to the study of 10 food samples and their corresponding recycled paper and board packaging. Samples of paper and board were irradiated in a thermal neutron flux of 1.26 . 1016n m-2 . s-1 for 15 hours to activate elements of interest. After a decay period of 10 days the paper and board was placed in contact with the corresponding foodstuff. The food was analyzed for any radioactivity migrating from the packaging by gamma-ray spectrometry. Samples were analyzed regularly during the 90 days contact time. Detection limits for the determination of migration was as low as a few µg/kg in the food. Results from the migration study have shown that, of the 60 elements measured, only Zn and Fe were detected in food, at concentrations of 0.012-0.25, and 0.045-0.11 mg/kg, respectively. This was despite the recycled paper and board samples being highly elevated in many other elements such as Cr (0.9-15.1 mg/kg) and Ba (3.3-75.4 mg/kg). The level of migration of Zn and Fe into food from packaging was insignificant compared to the UK recommended daily allowances of 15 mg, and, therefore, represented no hazard to human health.
Authors:S. Marei, A. Badran, A. Haggag, and E. Hanna
The extraction of Eu with Amberlite LA-2, TBP and HDEHP from HF, HCl, HBr, H2SO4, CH3 COOH and KI solutions was investigated. The extraction of Eu with TBP and LA-2 is small over a wide range of concentrations.
The extraction of Eu with HDEHP from HCl, HBr, and H2SO4 is inversely proportional to the third power of the acid concentration, while the extraction from KI is proportional to the
square of the extractant concentration. The extraction by the three extractants from H2SO4 in presence of small amounts of hydrogen halides is small. These extraction data can be used to separate Eu from Th and many
of the fission products. The presence of water-miscible alcohols and acetone generally increases the extraction of Eu from
H2SO4 and KI solutions.
The extraction of Am3+ and Eu3+ from aqueous picric acid solution by N, N-dinaphthyl-N, N-diphenyl-3,6-dioxaoctanediamide (LI) and 1, 1-(3, 6, 9-trioxaundecanedionyl)diphenothiazine (LII) was investigated by a radioactive tracer technique. Extraction distribution ratios of Am3+ and Eu3+ have been measured as a function of pH, picric acid concentration, extractant concentration, diluent and temperature. The extraction of Am3+ is preferred to that of Eu3+ for both LI and LII, and the latter gives larger separation factor than the former. The equilibrium constants and thermodynamic parameters of extraction reactions were also calculated.
Authors:H. Mimura, H. Hoshi, K. Akiba, and Y. Onodera
Microcapsules enclosing an extractant with strong affinity for Am were prepared by employing a biopolymer gel as an immobilization matrix. A relatively large separation factor between Am and Eu was exhibited by the microcapsule containing of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301, HA) and alginic acid (HALG). The chromatographic separation of these metal ions was accomplished by gradient elution through the column packed with HA-HALG.
The extraction of Tm with HDEHP from H2SO4, HCl and HBr is inversely proportional to the third power of the hydrogen ion concentration while the extraction is small
with HDEHP, LA-2 and TBP from binary mixtures of acids. The extraction of both Eu and Tm with HDEHP from KI solutions decreases
in the presence of small concentrations of H2SO4. The decrease is sharper in case of Eu leading to high separation factors between Eu and Tm from KI−H2SO4 mixtures.