Superelastic chitin nanofibril/chitosan aerogel for effective circulating and continuous oil-water separation

Elastic and hydrophobic aerogels have received a lot of attention in dealing with the increasing oil pollution due to their recyclable properties. Herein, we present an ultralight and superelastic aerogel with highly oriented polygon structure based on chitin nanofibril (ChNF) and chitosan (CS) by directional freezing. The chemical cross-linking enables good mechanical strength at low aerogel density. After 500 compression-release cycles, the aerogel can retain the deformation recovery rate of 88 % in air, demonstrating the excellent resilience. The bio-based aerogel has high absorption capacity (52-114 g/g) for various oils and organic solvents, and it is able to achieve the absorption retention of 90 % even after 20 absorption-extrusion cycles. Moreover, owing to the good elasticity, the pore size of the aerogel can be adjusted by compression to selectively separate water-in-oil emulsions of different particle sizes with separation efficiencies higher than 99.5 %. The bio-based aerogel with good cycle performance has broad application prospects in the field of oil-water separation.