Novel robust hierarchical porous membrane for uranium enrichment: fabrication, degradation behavior, and uranium sorption performance

Abstract

Extracting uranium from water bodies is urgently needed whether from a waste nuclear resource utilization or a new energy exploration perspective. Herein, a novel robust hierarchical porous CAP membrane was fabricated from the nucleophilic condensation of phenolphthalein and 2,6-difluorobenzonitrile, followed by classical amidoximation and nonsolvent-induced phase separation (NIPS) methods. Fast uranium uptake kinetics with sorption equilibrium at a mere 12 h was demonstrated, and the uranium uptake capacity was found to be 499 mg g⁻¹. The significant improvement in uranium enrichment performance was probably endowed by the outstanding hydrophilic surface and the hierarchical pores throughout the cross-sectional CAP membrane. Meanwhile, it was confirmed that the CAP molecular backbone may endure polymer degradation during amidoximation, and the amount of hydroxylamine used should be strictly controlled. The sorption mechanism was explored, and practical testing experimentally indicated the excellent desorption, reusability and selectivity properties of the CAP membrane. Overall, the easy processability, robustness and outstanding uranium sorption performance made the CAP membrane an ideal candidate for uranium enrichment from water bodies.