Synergistic Extraction of Erbium(III) by n-Octyl Phenyl Phosphinic Acid (OPPA) with Oxine and 2-Methyl Oxine in Different Diluents

Abstract

The synergistic extraction of erbium (III) was investigated using n-octyl phenyl phosphinic acid (OPPA) in combination with oxine and 2-methyl oxine in different diluents. The extraction efficiencies of these synergistic extractants for erbium were measured as a function of extractant concentration, pH, temperature and diluents. The composition of extracted species determined by slope analysis method indicates the formation of [Er(HA2)3(HOX)]org complex and was also confirmed by Infrared spectroscopy. Based on the experimental data, the values of the equilibrium constants as well as synergistic coefficients have been calculated. Both the donors (oxine/2-methyl oxines) exhibited almost similar synergistic effect with OPPA. The extraction of erbium with these solvents was exothermic in nature. Diluent dependency on synergism for OPPA-oxine/2-methyl oxine system was explained in terms of regular solution theory of Hildebrand. Experimentally determined solubility parameter of ternary adduct was correlated with theoretically obtained values.