Extraction of Ba2+, Pb2+ and Cd2+ into nitrobenzene by using strontium dicarbollylcobaltate in the presence of tetramethyl p-tert-butylcalix[4]arene tetraketone

From extraction experiments and gamma-activity measurements, the exchange extraction constants corresponding to the general equilibrium M2+(aq)+SrL2+(nb)double left right arrow ML2+(nb)+Sr2+(aq) taking place in the two-phase water-nitrobenzene system (M2+ = Ba2+, Pb2+, Cd2+; L = tetramethyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the order Ba2+< Cd2+< Pb2+.