Efficient rare earth enrichment through highly reversible physisorption on a negatively charged few-layer nanobelt platform

Abstract

Effective extraction of rare earth elements (REE) from the surrounding aqueous environment would relieve the thirsty demand of mining as well as the environmental pollution, thus advancing sustainability progress. Nevertheless, limited extraction capability and harsh enrichment conditions are still the notorious critical problems hindering this environmentally favorable path. Herein, we showcase a physisorption driving platform (InVO4) for effective REE enrichment. This delicately designed platform exhibits a unique few-layer structure and thus robust negatively charged surface in the aqueous environment, which implies its powerful attraction towards positively charged species. The adsorption trials towards REE ions have proved this anticipation with a superior adsorption capability of 317.3 mg/g towards Yb3+ and the adsorption reached quasi-equilibrium in only about 10 min. Moreover, this platform could be regenerated quickly and completely in a mild NaCl environment based on the quasi-cationic exchange strategy benefiting from the physisorption nature. Impressively, a ppb-level enrichment of REE ions from the aqueous was realized 78-fold increase from an initial concentration of 100 ppb. This environmentally benign and highly efficient adsorbent will be inspiring for a more sustainable utilization route for the recovery of REE resources.