Synergistic Extraction of Calcium and Strontium Into Nitrobenzene by Using Hydrogen Dicarbollylcobaltate and 1,2-Bis(Diphenylphosphino)Ethane Dioxide

摘要

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H~+B~-) in the presence of 1,2-bis(diphenylphosphino)ethane dioxide (DPPEtDO, L) has been investigated. The equilibrium data have been explained assuming that the species HL~+, HL_2~+, ML_2~(2+) and ML_3~(2+) (M~(2+) = Ca~(2+), Sr~(2+)) are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in nitrobenzene saturated with water have been determined. In the considered nitrobenzene medium, it was found that the stability constants of the complexes CaL~(2+)and CaL_3~(2+), where L is DPPEtDO, are somewhat higher than those of the corresponding complex species SrL~(2+) and SrL_3~(2+) with the same ligand L.