Calcium ionophore I as very effective extraction agent for trivalent europium and americium

The solvent extraction of microamounts of Eu3+ and Am3+ from water into nitrobenzene by means of a mixture of hydrogen dicarbollylcobaltate (H+B-) and calcium ionophore I (marked as the ligand L) was investigated. The equilibrium data have been explained assuming that the species HL+, HL2 +,ML2 3+ and ML3 3+ (M3+: Eu3+ or Am3+) are extracted into the organic phase. The extraction and stability constants of the cationic complex species in nitrobenzene saturated with water have been determined and discussed. It was proven experimentally that the ligand L could be considered as a very strong receptor for Eu3+ and Am3+.