Extraction of silver from water into nitrobenzene using sodium dicarbollylcobaltate in the presence of valinomycin

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the Ag+(aq) + NaL+(nb) ↔ AgL+(nb) + Na+(aq) equilibrium in the two-phase water-nitrobenzene system (L=valinomycin; aq=aqueous phase, nb=nitrobenzene phase) was evaluated as log Kex(Ag+,NaL+) = -0.6 ± 0.1. The stability constant of the valinomycin-silver complex in nitrobenzene saturated with water was calculated: log βnb(AgL+) = 4.6 ± 0.1. The stability constants of complexes of some univalent cations with valinomycin were summarized and discussed. (author)