Highly elastic photothermal nanofibrillated cellulose aerogels for solar-assisted efficient cleanup of viscous oil spill.

Frequent oil spills and illegal industrial pollutant discharge cause ecological and resource damages, so it is necessary to establish efficient adsorption and recovery strategies for oils in wastewater. Herein, inspired by solar-driven viscosity-breaking, we propose a facile approach to fabricate multifunctional nanofibrillated cellulose-based aerogel with high elasticity, excellent photothermal conversion, efficient selective oil adsorption and antibacterial properties. Firstly, copper sulfide (CuS) nanoparticles were in situ deposited on the template of oxidative nanofibrillated cellulose (ONC), aiming at achieving efficient photothermal effect and antibacterial properties. Ethylene glycol diglycidyl ether (EGDE) was employed to establish multiple crosslinking network between CuS@ONC and polyethyleneimine (PEI). A thin hydrophobic PMTS layer deposited on the surface of aerogel via a facile gas-solid reaction ensured stable oil selectivity. The resulting composite aerogel can rapidly adsorb oil under solar self-heating, significantly reducing the adsorption time from 25 to 5 min. Furthermore, it exhibits excellent adsorption capacities for various oils, retaining over 92 % of its initial capacity even after 20 adsorption-desorption cycles, and the antibacterial properties extend its lifespan. This work offers a promising method for constructing multifunctional aerogels for efficient oil-water separation, especially beneficial for high-viscosity and high-melting-point oil cleanup.