Extraction behavior of selected rare earth metals from acidic chloride media using tetrabutyl diglycolamide

Rare earth elements (REEs) are vital to modern, high-tech devices. Recycling REEs from post-consumer electronics can potentially diminish supply chain risks. Toward that end, liquid–liquid solvent extraction of various REEs was investigated with tetrabutyl diglycolamide (TBDGA) in 1-octanol from hydrochloric acid media. Metal partitioning to the organic phase was shown to increase as [Cl−] increased. In contrast, increasing [H+] did not improve extraction. The use of the polar diluent 1-octanol provided high extraction efficiency, especially for the partition of heavy lanthanides from solutions of high chloride concentration. Although the polar diluent also extracted molar amounts of water and acid, it was concluded that a neutral metal/TBDGA complex as mainly the di-solvate was extracted, and that complexation was observed to be exothermic. These results indicate that REE extraction from aqueous chloride solutions can be efficient without the use of high acid concentrations.