Extraction of univalent and divalent cations and Eu ³⁺ into nitrobenzene using calcium ionophore V

The extraction of univalent (Li + , H 3 O + , Na + , Ag + , K + , NH 4 + , Tl + , Rb + , and Cs + ), divalent (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Pb 2+ , Cu 2+ , Zn 2+ , Cd 2+ , UO 2 2+ , Mn 2+ , Co 2+ , and Ni 2+ ) and Eu 3+ cations in the system water – nitrobenzene in the presence of calcium ionophore V (abbr. L) has been investigated. The stability constants of the complexes of NaL + , SrL 2+ and EuL 3+ have been determined from the extraction of sodium picrate, strontium picrate, and europium triflate by the nitrobenzene solution of calcium ionophore V. The stability constants of other univalent and divalent cations have been determined from the competitive extraction in the systems: water – univalent cation nitrate – calcium ionophore V – nitrobenzene solution of sodium salt of dicarbollylcobaltate anion and water – divalent cation nitrate – calcium ionophore V – nitrobenzene solution of strontium salt of dicarbollylcobaltate anion. While the stability constants of univalent cations are low, those of divalent cations and Eu 3+ are very high.