Mixed Ligand Chelate Extraction of Lanthanides with 5, 7-Dibromo-8-quinolinol and 4, 4′-(5-Nonyl)-2, 2′-dipyridylamine Systems

Abstract

The equilibrium extraction behavior of a series of representative tervalent lanthanide ion, Pr, Eu and Yb, using 5, 7-dibromo-8-quinolinol (DBQ) as a chelating extractant, either alone or in combination with 4, 4′-(5-nonyl)-2, 2′-dipyridylamine (NDPA) as an adductant has been studied. The stoichiometry, extraction constants, and separation factors were determined. The results demonstrate that lanthanides are extracted as simple chelates, LnQ₃, at lower HQ concentrations, or as self-adduct chelates, LnQ₃•HQ, at higher HQ concentrations. In the presence of NDPA, mixed ligand chelates of either the type LnQ₃•NDPA or LnQ₂(HA)•NDPA (were HA^- is the hydrogensuccinate ion) have been observed.