Scalable and facile fabrication of sulfonic-acid-functionalized porous hypercrosslinked polymers for efficient recovery of rare earth elements from tailing wastewater

The separation and enrichment of rare earth elements (REEs) from tailing wastewater is of great significance for the sustainable supply of REEs and environmental remediation. As Al 3+ exhibits extreme similar properties with REE 3+ , selective recovery of REE 3+ from the sulphate tailing wastewater remains a considerable challenge. Based on the difference in the binding stability of REE 3+ and Al 3+ with sulfate ions, the utilization of sulfonic acid groups may provide a promising method for enhancing the selectivity of REE 3+ /Al 3+ in the sulphate aqueous solution. Herein, a series of sulfonic-acid-functionalized hyper-crosslinked polymers (SHCP-Ps) were successfully synthesized through a facile, scalable and one-step method catalyzed by chlorosulfonic acid, which has the advantages of high sulfonic acid density (3.27 mmol/g), specific surface area (1044.6 m 2 /g), abundant micropores and superhydrophilicity. These properties result in SHCP-P exhibiting fast adsorption kinetics (30 min) and high adsorption capacities (106.78 mg/g (La), 111.99 mg/g (Eu) and 126.27 mg/g (Lu)). Additionally, it exhibits extremely high REE 3+ /Al 3+ selectivity (SF(La/Al) = 6929, SF(Eu/Al) = 4810, SF(Lu/Al) = 3003) in sulfate medium, surpassing that of most existing REEs adsorbents. Upon application of SHCP-P to actual wastewater, the recovery rate of total REE 3+ was observed to reach 87 %, while the adsorption rate of Al 3+ was found to be 0. Simultaneously, SHCP-P exhibits both high reusability and magnification synthesis capabilities. The results indicate that SHCP-P has significant potential for industrial applications in the selective recovery of REEs from tailing wastewater.