Interference of elements upon extraction by macrocyclic extractants

The extraction of cations of a series of alkali and alkali-earth metals, along with Pb(II), Rh(III), and Pd(II) with crown, thiacrown and azacrown ethers from picric and nitric acid solutions was studied. Upon the extraction of metal cations with macrocyclic extractants, the interference of those cations on the extraction of one another was observed in polar solvents. The causes of this phenomenon are revealed, and a mechanism for the suppression of extraction of the microcomponent with the macrocomponent is proposed. Upon the simultaneous extraction of americium (III) and europium (III) with calixarenes the co-extraction was noted for the first time, resulting in the good extraction of Am(III) from nitric acid solutions. We hypothesize on the formation of a mixed nitrate complex of americium and europium that can be effectively extracted into an organic phase with calixarenes.