Hybrid aerogels derived from banana peel and waste paper for efficient oil absorption and emulsion separation

Developing separation materials for rapidly oil absorption and emulsions separation is urgently needed and remains a great challenge. Here, a biomass-derived banana peel/waste paper (BPWP) hybrid aerogel with hierarchical porous structure has been successfully fabricated via combination of freezing-cast, freeze-drying and pyrolysis approach, for application in oil adsorption and water-in-oil emulsions separation. In this hybrid system, the microsheets that derived from banana peel immobilize were immobilized on surface of the waste paper fibers, forming a hierarchical structure. The resulting BPWP aerogels exhibit a compression strain of 75%, high-hydrophobicity (WCA of 149.3°)/underair superoleophilicity (OCA of 0°), and high porosity, which can absorb of free oils in water with high oil sorption capacity of 35–115 times its own weight. Moreover, these aerogels effectively separate various surfactant-stabilized water-in-oil emulsions driven solely by gravity, with high separation efficiency above 99.6% and higher fluxes of up to 8550 L m−2 h−1 than traditional filtration membranes with pressure driven, even the sizes of emulsified droplets are smaller than the pore size of the BPWP aerogels. More importantly, the BPWP aerogels exhibit a superior antifouling property and regenerability for emulsion separation, which match well with the requirements for treating the real emulsions. Due to the advantages of banana peel/waste paper aerogels in rich source and high oil separation efficiency, the obtained banana peel/waste paper aerogel can be a potential candidate in industrial applications and environmental protection. This work opens up a new avenue for design new hierarchical biomass-derived aerogels for a variety of applications including energy storage, sensors and pressure-sensitive electronics.