Green approach to facilely design hydrophobic aerogel directly from bagasse

Abstract

Under the promotion of sustainability, aerogels derived from bagasse have been developing. The reported bagasse aerogels are normally prepared by the treatment of bagasse with dissolution and regeneration or the removal of hemicellulose and lignin, and their hydrophobicity is achieved by silanes, leading to complicated and even environmental-unfriendly processes. In this report, we designed a novel, green and facile technique to prepare hydrophobic bagasse aerogels by milling of bagasse, mixing with alkyl ketene dimer (AKD) emulsion, freeze drying and thermo-crosslinking. Interestingly, AKD behaved as strength agent to endow aerogels with lower density, higher porosity, and better strength in comparison with the pristine bagasse aerogel. Increasing AKD or slurry concentration, their density and porosity displayed an increase and decrease tendency, respectively, resulting in a normal distribution of their oil absorption properties. Optimal hydrophobic bagasse aerogel was obtained at an AKD content of 10 wt% and slurry consistency of 3 wt%, whose density, porosity and water contact angle was 47.3 mg cm–3, 95.9 % and 148 °, respectively. It exhibited a high oil absorption capacity (31.65 g g–1) and a low thermal conductivity (36.28 mW m–1K–1), which could be applied for oil/water or emulsion separation and thermal insulation. The fabrication method would provide a novel idea for other bio-based hydrophobic aerogels.