Novel Flexible Hierarchical Porous Membrane for Uranium Enrichment: Fabrication, Degradation Behavior, and Uranium Sorption Performance

Abstract

Extracting uranium from water bodies is urgently needed whether from waste nuclear resource utilization or new energy exploration perspective. Herein, a novel flexible hierarchical porous CAP membrane was fabricated from the nucleophilic condensation of phenolphthalein and 2,6-difluorobenzonitrile, followed by classical amidoximation and nonsolvent induce phase separation (NIPS) methods. The resultant CAP possessed excellent processability, and it was verified that CAP molecular backbone may endure polymer degradation in face of high concentrated hydroxylamine during amidoximation. A fast uranium uptake kinetics with sorption equilibrium at mere 12 h was demonstrated, and the uranium uptake capacity was found to be 499 mg/g, which was 4.36-fold that of the traditional PAO membrane. The significant improvement of uranium enrichment performance was probably endowed by the outstanding hydrophilic surface and the hierarchical pores throughout the cross-sectional CAP membrane. Meanwhile, the sorption mechanism was explored, and practical testing experimental indicated the ideal desorption, reusability and selectivity properties of CAP membrane. This study provided new insights into the design and preparation of high-performance uranium adsorbents.

Keywords: Uranium enrichment, Flexible hierarchical porous membrane, Degradation