Studies on synergistic solvent extraction of rare earth elements from nitrate medium by mixtures of 8-hydroxyquinoline with Cyanex 301 or Cyanex 302

Synergistic solvent extraction of rare earth elements (REEs) from nitrate medium was investigated with mixtures of 8-hydroxyquinoline (HQ) and acidic organophosphorus extractants, bis(2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex 301) and bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex 302). The extraction behavior of Cyanex 301/Cyanex 302 and their binary mixtures with HQ towards several lanthanoids (La, Nd, Sm, Tb, Ho, Tm) and yttrium (Y) was investigated. The separation ability of REEs was studied according to the various extraction effects. The extraction mechanisms for yttrium were studied with the methods of slope analysis and constant moles in the synergistic systems. The extracted compounds, the equilibrium constants, and thermodynamic functions were also determined.