Preparation of meso-porous aromatic frameworks for rapid ion extraction from high salt and corrosion environments

Abstract

Extraction of uranium from seawater could be capable of meeting the maintenance supply of nuclear energy fuel for thousands of years into the future. However, the low capture capacity of conventional microporous adsorbents for uranyl ions is attributed to the electrostatic repulsion of the adsorbed ions, which hinders the migration of foreign metal ions inside the pore channels. Here, we adopt silica of 10–20 nm size as a template to obtain two porous aromatic framework (PAF) adsorbents with mesoporous cavities. Meso-PAFs provide large channels for the rapid adsorption of uranyl ions with a capacity of ∼200 mg g⁻¹ in 1 h (∼10 ppm). Notably, they exhibit an average adsorption capacity of 12.4 mg g⁻¹ during a 20-day extraction from natural seawater, nearly tenfold higher than that of the classical amidoxime-based microporous materials (POP-AO, 1.32 mg g⁻¹). This study provides inspiration for preparing PAFs containing mesoporous channels to provide large enrichment space and alleviate electrostatic repulsion, suggesting a reliable scheme for the future high-performance extraction of nuclear energy from seawater.