Amine Sorbents for Selective Recovery of Heavy Rare‐Earth Elements (Dysprosium, Ytterbium) from Aqueous Solution

Abstract The supply shortages of rare‐earth elements (REEs) necessitate low‐cost and efficient processes for the recovery of valuable REE commodities. A covalently anchored polyethylenimine‐epoxysilane‐silica sorbent was prepared by simple wet impregnation and engineered to afford selective separation of REEs into heavy and light element groups. Remarkably, the sorbent allowed the cyclic recovery of >80 % of ppb‐level REEs and around 0 % of the ppm‐level Na, Mg, Ca from acid mine drainage solution, thus highlighting the applicability of the sorbent for concentrating REEs from practical waste streams. Moreover, the sorbent is promising for pre‐concentration of 7.6 wt% REEs, exceeding the U.S. Department of Energy REEs pre‐concentration objective. Notably, the use of an immobilized amine sorbent for the selective separation of the heavier REEs by an adsorption‐elution process allowed only the heavier species (>99 % Dy+Yb) to be concentrated and separated. This represents a practical and highly efficient sorbent adsorption‐desorption procedure that both concentrates and separates high‐purity REE from low‐concentration REE sources.