Extraction of europium and americium into nitrobenzene by using synergistic mixture of hydrogen dicarbollylcobaltate and tetraisopropyl methylene diphosphonate

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of tetraisopropyl methylene diphosphonate [T(iPr)MDP, L] has been investigated. The equilibrium data have been explained assuming that the complexes HL+, HL2 (+), ML2 (3+), ML3 (3+) and ML4 (3+) (M3+ = Eu3+, Am3+) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It was found that the stability constants of the corresponding complexes EuL (n) (3+) and AmL (n) (3+), where n = 2, 3, 4 and L is T(iPr)MDP, in water-saturated nitrobenzene are comparable.