Multifunctional cellulose–based aerogel with ultra-stable superhydrophobicity and thermal responsiveness for oil–water separation

Aerogels are widely used in environmental remediation, but their application is hindered by brittleness, limited oil absorption and poor separation of viscous crude oil. In this study, a multifunctional superhydrophobic aerogel with electrothermal and photothermal effects was prepared from bacterial cellulose (BC), methyltrimethoxysilane (MTMS), and hydroxylated carbon nanotubes (HCNT) by soft-hard synergistic and directed freezing. The prepared aerogel exhibited an oriented layered porous structure with excellent compressibility and oil retention capacity. The aerogel maintained 250 cycles of 25 % strain compression without structural degradation. Because of the presence of Si-CH 3 , the aerogel maintained a water contact angle above 153° across pH 1–13 and retained superhydrophobicity (WCA˃150°) even after severe abrasion. The prepared aerogel exhibited excellent absorption capacities for various organic solvents and oils, ranging from 45 g/g for n-hexane to 112 g/g for dichloromethane, and retained 96 % of dichloromethane through capillary locking. The well-dispersed HCNT enabled efficient photothermal (117.7 °C) and electrothermal (126.7 °C) conversion, facilitating rapid and continuous separation of crude oil/water mixtures at high fluxes (4.47 × 10 4  kg·m −3 ·h −1 and 8.15 × 10 4  kg·m −3 ·h −1 under photothermal and electrothermal conditions, respectively). This material holds great potential for practical application in high efficiency oil-water separation, particularly in challenging conditions involving viscous crude oil.