Green Preparation of Waste-Derived Nanocellulose/Chitosan/Ag Aerogels for Multifunctional Water Treatment

​Waste-derived nanocellulose aerogels offer a sustainable route for converting lignocellulosic residues into functional porous materials, but balancing antibacterial activity, catalytic performance, adsorption capacity, and Ag-release control remains challenging. In this study, sugarcane bagasse was used as a biomass source to prepare waste-derived nanocellulose through alkaline treatment, hydrogen peroxide bleaching, high-pressure homogenization, and sonication. The nanocellulose was combined with chitosan to form porous aerogels by freezing and freeze-drying, followed by in situ green loading of Ag nanoparticles using standardized green tea extract as the reducing medium. The optimized Ag-WNC/CS-A-3 aerogel retained high porosity, improved mechanical stability, and a BET surface area of 66.4 ± 5.2 m²/g. It showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus, efficient 4-nitrophenol reduction with an apparent rate constant of 0.184 ± 0.017 min⁻¹, and enhanced adsorption toward methylene blue and Pb(II), with equilibrium capacities of 118.7 ± 7.1 mg/g and 72.4 ± 6.3 mg/g, respectively. Although higher Ag loading slightly improved antibacterial and catalytic performance, it reduced adsorption balance and increased Ag release. Overall, Ag-WNC/CS-A-3 provided the most balanced combination of structural integrity, multifunctional activity, reuse stability, and Ag-release control. This work supports a sustainable design strategy for recoverable bio-based aerogels in antibacterial, catalytic, and water-treatment applications.