Ambient Mechanochemical Assembly of Chitosan-Supported COF Aerogels for Dual-Functional Oil/Water Separation and Dye Remediation

Covalent organic frameworks (COFs) are predominantly limited to microcrystalline powders, which severely restricts their processability and recovery in continuous water treatment. Herein, we report a rapid (<60 min), solvent-minimized mechanochemical strategy to fabricate macroscopic chitosan-supported COF aerogels under ambient conditions. By leveraging a confined cocrystal-templating approach, imine-linked COFs undergo controlled in situ growth on functionalized chitosan via mechanical milling, completely eliminating energy-intensive solvothermal steps. The resulting hierarchical aerogels exhibit exceptional dual-functional performance: gravity-driven oil–water separation efficiency exceeds 99.8% for both low- and high-density oil, with an ultrahigh adsorption capacity of 14,130 mg/g for viscous silicone oil. For dye remediation, the aerogels achieve rapid cationic dye uptake (equilibrium within 40–60 min) with maximum adsorption capacities of 285.1 mg/g for methylene blue and 1168.4 mg/g for safranine T, alongside >99.8% selective removal from mixed anionic/cationic systems. Molecular dynamics and density functional theory (DFT) calculations confirm that tunable framework hydrophobicity and strong electrostatic compatibility govern targeted pollutant capture. Critically, the aerogels retain >96% of their initial performance after five regeneration cycles under harsh acidic, alkaline, and saline conditions. This room-temperature, trace-solvent fabrication pathway bridges the gap between laboratory COF synthesis and scalable engineering, providing a robust, cost-effective platform for continuous wastewater purification and sustainable separation operations.