Synergic extraction of Eu(III) and Tb(III) by 2-thenoyltrifluoroacetone and tribenzylamine

Synergic extraction of Eu(III) and Tb(III) with 2-thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) as neutral donor ligand has been studied in chloroform from perchlorate media at lower pH range. The stoichiometric composition of the adduct was established as M(TTA)₃ · 3TBA for both the elements, having a coordination number 9. The formation constants K_3,0 and K_3,3 and stability constant _3,3 of the organic phase reaction have been calculated. The effect of temperature on the extraction has also been studied. The adducts are stabilized by the large exothermic enthalpy change. The calculated thermodynamic functions such as H, S and G were used to elucidate the mechanism of synergism in which the coordination numbers of the lanthanide ions increased.