Europium separation factor

By increasing the temperature of an ion exchange system, more rapid separation can be performed. In fact, temperature modifies the separation factor of two neighbor elements. For example, by increasing the temperature from 25°C to 95°C, the 1.5 samarium-europium separation factor becomes 1.8 and the europium-gadolinium 1.1 separation factor goes to 1.5. Thus the difficult Eu-Gd separation at 25°C becomes "easy" at 95°C. 

The thio-derivative 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (BMPPT), gives good americium/europium separation factors in synergistic extraction systems (Smith et al. 1987, Ensor et al. 1988). 

Fig. 6. Histogram representation of americium/europium separation factors (as representative of lanthan-ide/actinide group separation factors) for a representative collection of separation methods ...

The analysis of the extraction by CPo21 data reveals a 1 1 metal ion-to-ligand ratio for europium and thorium. The selectivity factors indicate a good selectivity toward these two cations with respect to Mn2+, Pb2, Cd2+, Fe2+, Ni2+, and Co2+, among which only cadmium is a weakly radioactive fission product.155 A synergistic extraction of almost three orders of magnitude was evidenced for the extraction of La3+, Nd3+, Eu3+, Ho3+, Lu3+ with 4-benzoyl-3-methyl-l-phenyl-5-pyrazolone and CPo21 however, it does not improve the separation factors between lanthanides.156... 

Under the same conditions, in contrast to what is observed for calix[4]arene-bearing CMPO moieties, with CPil2, distribution ratios of lanthanides increase from the lightest lanthanide, lanthanum, to europium. Americium can be easily separated from the lightest lanthanides (separation factor DAm/La > 20, DAm/Ce =15, /lAlll,Nd = 10, UAi /si = 7.5, DAm/Eu = 6), which are the most abundant lanthanides in fission-product solution. Cavitands bearing picolinamide (Cv5) or thiopicolin-amide (Cv6) residues seems much less selective than their calixarene counterparts, giving SAm/Eu < 2.18... 

No retention of a emitters was observed during this treatment, and the separation factors of transplutonium elements in relation to europium are respectively = 11.2 a jU = 1.83 = 1.23. 

M DOP, the mixing time being 10 minutes. Under these conditions the Eu/Am separation factor is about 30, and triple extraction transfers 97 europium into the organic phase. 90% Am stay in the aqueous phase, where the content of Eu is no higher than 3%. Americium can then be quantitatively extracted by 0.04 M DOP toluene solution, the phases being mixed for 45 minutes. 

Table III. Effect of H2MEHP Concentration on the Separation Factor for Americium and Europium in Talspeak Partitioning...

Europium/americium separation factors for a series of acidic extractants (Sekine and Dyrssen 1964). 

On the other hand, Dyrssen and Liem (1960) report (table 7) greater variation in both distribution ratios [for americium and europium extraction by dibutyl phosphoric acid (HDBP)] and in separation factors as a function of diluent. The separation factors and distribution coefficients are correlated (more or less consistently) inversely with the distribution ratio of the extractant between the phases. In this system, the largest separation factors are observed in n-hexane, chloroform, and carbon tetrachloride. Diluents capable of direct coordination (i.e., those possessing potential oxygen-donor atoms) are correlated with reduced distribution ratios and separation factors. The observations of greater separation factors in non-complexing diluents suggest that more effective separation is observed when the inner-coordination sphere of the hydrophobic complex is not disturbed. 

Dodsworth ES, Vlcek AA, Lever ABP (1994) Factorization of hgand-based reduction potentials. Inorg Chem 33 1045-1049 Donard OFX, Weber JH (1988) Volatilization of tin as stannane in anoxic environments. Nature 332 339-341 Donohue T (1977) Photochemical separation of europium from lanthanide mixtures in aqueous solution. J Chem Phys 67 5402-5404... 

While those coefficients obtained from the porous-type resins are similar to those from the gel-type ones, the number of theoretical plates increases by a factor of about 3 and the tailing of elution curve decreases remarkably. Three groups, of americium and curium, of yttrium and of europium to cerium, can be well separated with 11.7 M hydrochloric acid which is a commercially available chemical reagent, as shown in Figure 2. 

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