Synthesis of novel phosphate-based hypercrosslinked polymers for efficient uranium extraction from radioactive wastewater

The uranium extraction from radioactive wastewater is vitally important for both the sustainable nuclear energy and environmental protection. However, the efficient extraction of uranium (VI) faces great challenges due to the complex compositions of radioactive wastewater. In this work, phosphate-based hypercrosslinked polymer (HCP) is designed and synthesized via the Friedel-Crafts polymerization of different aryl phosphate with crosslinking monomer for efficient uranium (VI) extraction. The HCP has uranophilic phosphate group, large specific surface area and mesoporous structure. It can effectively adsorb uranium (VI) from solution under various pH conditions and the adsorption efficiency can achieve 98 %. The maximum sorption capacity of HCP reaches 302 mg/g at pH 7.0 with a sorbent dosage of 0.33 g/L, which is higher than many other phosphate-based polymer. Meantime, it shows good sorption selectivity for uranium (VI) over many other coexisting metal ions. It shows recyclability and can be well applied to the fixed-bed sorption column for long-time uranium (VI) extraction. Investigations on sorption mechanism reveals that the coordination effect between phosphate groups and uranium (VI) ions enhances the effective sorption of uranium (VI) on HCP. This work provides a facile way to construct heterogeneous phosphate sorbents, and demonstrates their potential for practical application in uranium (VI) recovery from radioactive wastewater.