Fabrication of a bio-based benzoxazine-modified hydrophobic cellulose aerogel for efficient oil-water separation

An all-biomass-based benzoxazine-modified cellulose aerogel was prepared. • The aerogel has enhanced mechanical strength and hydrophobic lipophilicity. • The aerogel enables continuous separation of oil-water mixtures and emulsions. • The aerogel enables continuous oil-water separation, including emulsions. Oil spills in oceans and the discharge of oily wastewater from industries significantly impact the environment and human health. Recently, biomass aerogels have gained attention for oil-water separation due to their renewability and excellent adsorption capacity. However, the fragility and amphiphilic nature of cellulose aerogels limit their practical use in such applications. A novel all-biological benzoxazine was developed for cellulose aerogel modification. Through chemical cross-linking, freeze-drying, soaking, and thermal curing processes, a modified cellulose aerogel (p(G-md)/CA) with exceptional properties was successfully created. This lightweight material features high porosity, remarkable elasticity, and strong hydrophobicity (water contact angle of 135°), while demonstrating impressive pressure resistance (915 kPa at 90% strain). The preparation method offers significant advantages: simplicity, cost-effectiveness, environmental friendliness, and scalability for industrial production. The p(G-md)/CA aerogel rapidly and selectively adsorbs organic solvents and oils, demonstrating high adsorption capacity and excellent recyclability. After 50 reuse cycles, its adsorption capacity retains over 80% of its initial value (37 g/g). Additionally, the aerogel can serve as an efficient adsorption medium in continuous separation systems, effectively separating oil-water mixtures, including emulsions. As such, this polybenzoxazine-modified cellulose aerogel holds significant potential for practical applications in marine oil spill cleanup and industrial wastewater treatment.