A bio-inspired ambient-pressure-dried hierarchical aerogel for ultrafast uranium harvesting from seawater

Continuous porous aerogels are promising materials for rapid and large-scale uranium extraction from seawater. However, their fabrication faces challenges regarding precise structural control, high mechanical strength, resistance to seawater-induced swelling and shrinkage, and the high energy consumption associated with sustained low-temperature and vacuum pumping. Inspired by plant pore structures, an ambient pressure drying strategy combining cryo-polymerization with a "melting-crosslinking" process is proposed for the large-scale fabrication of aerogels designed for ultrafast uranium uptake from seawater. The aerogel is formed by the chemical crosslinking of imidazole cationic monomers copolymerized with amidoxime, and physical crosslinking with cellulose acetate, creating a dual crosslinking structure. This dual crosslinking structure imparts high mechanical strength and resistance to seawater-induced swelling and shrinkage, maintaining structural integrity even after 10 drying cycles. The incorporation of antibacterial components enables long-term operation in seawater. The hierarchical structure, with over 99 % ultra-connected channel volume, enhances uranium adsorption, achieving an ultrafast uptake of 11.89 mg g−1 within 20 days. This work presents a new low-energy shaping strategy for aerogels used in seawater uranium extraction, with potential applications in other fields requiring high-strength aerogels with hierarchical structures.