Extraction of Pb2+ with sodium dicarbollylcobaltate in the presence of 15-crown-5

Abstract

From extraction experiments with 22 Na as a tracer, the exchange extraction constant corresponding to the equilibrium Pb2+ (aq)+2 NaL+ (nb)⇄PbL22+ (nb)+2 Na+ (aq) in the two-phase water-nitrobenzene system (L = 15-crown-5; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (Pb2+ , 2NaL+ ) = 4.7±0.1. Moreover, the stability constant of the complex PbL22+ in nitrobenzene saturated with water was calculated for a temperature of 25 °C as log βnb (PbL22+ ) = 17.9±0.1.