Synergistic extraction of Nd(III), Tb(III) and Lu(III) ions with a mixture of picrolonic acid and benzo-15-crown-5 in chloroform

Abstract

SummaryThe synergistic mixture comprising picrolonic acid (HPA) and benzo-15-crown-5 (B15C5) in chloroform has been used for the extraction of Nd3+, Tb3+and Lu3+as representatives of lanthanide(III) ions from pH 1-2 solutions having ionic strength of 0.1 mol l−1(K+/H+, Cl−). The composition of the extracted species has been determined as M(PA)3·nB15C5 where M is Nd, Tb and Lu andn= 1 or 2. The acid dissociation constant (pKa) has been evaluated to be 2.52 ± 0.01. The influence of various anions and cations on the extraction of these lanthanide(III) ions has also been studied and only oxalate and thiosulphate among the anions and Cu2+, Fe3+, Zn2+and Ni2+among the cations have some deleterious effect. The extraction equilibrium constants have been evaluated and discussed.