Mixed Ligand Chelate Extraction of Lanthanides: I. 8-Quinolinol Systems

Abstract

Abstract A detailed study of the equilibrium extraction behavior of a series of representative tervalent lanthanide ions, La, Pr, Eu, Ho, and Yb, into chloroform solutions containing either 8-quinol-inol (HQ) alone or mixed with 1,10-phenanthroline (phen), was carried out. The results demonstrated that, except for La which extracted as a simple chelate, LaQ3, the lanthanides extract as self-adduct chelates, LnQ3 · 2HQ, and at higher HQ concentrations, LnQ3 · 3HQ. In the presence of phen, mixed ligand chelates of all the lanthanides but La of the formula LnQ3 · 2HQ · phen are formed. The use of the experimental parameters, pH, concentration of both HQ and phen to optimize the separation of the lanthanides is discussed. It is concluded that chelate extraction systems in which adduct and mixed ligand complexes are formed enhance separation capability.