Applications of the binary mixture of sec-octylphenoxyacetic acid and 8-hydroxyquinoline to the extraction of rare earth elements

In the present work, a binary mixture of sec-octylphenoxyacetic acid (CA12, H2A2) and 8-hydroxyquinoline (HQ) was applied to the extraction of rare earth elements. The mixture had synergistic extraction effects on all the lanthanoids (except polonium) and yttrium. The separation ability of rare earth elements was studied according to the various extraction effects. As representatives of light, medium, and heavy rare earth elements, the compositions of the extracted species for cerium, terbium, and lutetium were investigated by the slope analysis method and constant molar ratio method. The values of the equilibrium constants and the thermodynamic functions were also determined.

► Synergistic extraction of rare earth elements in HNO3 with CA12 and HQ.
► Determination the optimum separation and stripping conditions for rare earths.
► Investigation the extraction stoichiometries of rare earth elements with CA12, HQ, and their mixtures.
► Achievement quantitative stripping of rare earths with 0.1 mol L− 1 HNO3.