Directional Lamellar and Underwater Superelastic Nanocellulose/Phytic Acid-Functionalized Chitosan Aerogels for Uranium Extraction from Seawater

Developing eco-friendly adsorbing materials with high mechanical strength and superior uranium adsorption capacity is vital for sustainable nuclear energy. Herein, the GCNF/PCS aerogel with an aligned lamellar structure was fabricated via directional freezing. 3-Glycidyloxypropyltrimethoxysilane (GPTMS) was used to modify the cellulose nanofibril (CNF) skeleton to improve mechanical strength, while phytic acid-functionalized chitosan (PCS) was introduced to enhance uranium adsorption performance. Benefiting from the stress-dispersing aligned lamellar structure, the GCNF/PCS aerogel showed high mechanical strength and a compression recovery rate. Consequently, the aerogel exhibited excellent reusability, retaining 75% adsorption capacity after five cycles. Furthermore, the introduction of PCS increased the SBET of the system, enabling the aerogel to have abundant uranium adsorption sites and achieving maximum adsorption capacity of uranium (717.11 mg/g). The aerogel demonstrated exceptional uranium selectivity (U/V = 73.14) and achieved a high level in the actual seawater test (1.03 mg/g over 14 days). This work provides a promising strategy for developing seawater uranium extraction materials for complex environments.