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-CH3, 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 × 104 kg·m-3·h-1 and 8.15 × 104 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.