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

摘要

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.