Purification of ytterbium using a cationic resin

The growing demand for high quantities of Rare Earth Elements (REE) led to the need for novel processes for their recovery and purification. Adsorption is a promising technique for purifying REE as it eliminates the use of hazardous chemicals. This work evaluates the use of the commercial polymeric resin Dowex 50W-X8 for polishing a ytterbium (Yb) stream contaminated with other REE present when recycling neo-magnets. Adsorption equilibrium isotherms and breakthrough curves of different REE (Yb, La, Nd and Er) and binary mixtures were measured. The adsorption capacity at concentrations of 300 mg L⁻¹ ranges from 179 to 205 mg g⁻¹ following the order Er > Nd > Yb > La. The steepness of the isotherms follows a different order: Nd > Er > La > Yb, indicating that Yb will be the less adsorbed REE in a mixture. A mathematical model was fitted to single component data and was successfully used to predict the behavior of binary breakthrough curves.