Photosensitive COFs-carboxylated nanocellulose membrane enables high-efficiency uranium extraction via synergistic...

Uranium present in radioactive wastewater poses serious radiological and environmental threats due to its long half-life, high mobility, and bioaccumulation potential. Herein, we report a photocatalytic composite membrane (4PE-TT-CNCM1) for efficient uranium recovery, fabricated through in-situ growth of a photo-responsive covalent organic framework (COF) on carboxylated nanocellulose (CNC). Comprehensive characterization and mechanism studies have revealed that 4PE-TT-CNCM1 effectively suppresses COF aggregation through the CNC carrier, exposes abundant active sites, and integrates synergistic coordination complexation with photoreduction to efficiently capture and reduce soluble UO₂²⁺. Without any sacrificial reagents, the membrane exhibits outstanding photocatalytic performance, including an adsorption capacity of 902.6 mg·g^-1, high selectivity (K_d = 2.1 × 10⁵ mL·g^-1), 100% antibacterial performance (Escherichia coli and Pseudomonas aeruginosa), > 90% removal efficiency over 5 cycles, and low fabrication cost ($1.557·unit^-1). In a membrane-based photocatalytic platform, 4PE‑TT‑CNCM1 extracts uranium with efficiencies of 87.9% from natural seawater and 91.3% from real wastewater, demonstrating its practical potential for uranium extraction and radioactive‑water remediation. This work presents an efficient, stable, and sustainable strategy for COF-based membrane engineering, uranium recovery, and nuclear-energy sustainability.