Structural and adsorptive optimization of bacterial cellulose aerogels with high porosity, low shrinkage, and enhanced thermal stability

This study focuses on optimizing bacterial cellulose (BC) aerogels via freeze-drying to address oil pollution in water. By investigating BC concentrations (0.1–1.1%), solution pH (3–8), and tert-butanol solvent replacement, the structural and functional properties of aerogels were systematically evaluated. Results revealed that BC concentration critically influenced morphology and porosity. At 0.7% BC concentration, the aerogel exhibited a dense 3D network structure with a porosity of 99.2% and minimal linear shrinkage (9.33%). Adjusting solution pH further enhanced performance: at pH 4, the aerogel achieved optimal uniformity in lamellar structure, highest porosity (99.4%), and reduced shrinkage (8.33%). Tert-butanol replacement significantly improved pore architecture, increasing porosity to 99.7%, reducing shrinkage to 6.28%, and elevating specific surface area to 36.3 m²/g while decreasing average pore size to 19.9 nm. Structural analyses confirmed that acid/base treatments did not alter the native cellulose I crystallinity or functional groups. Thermal stability was enhanced post-replacement, with residual mass at 600 °C rising from 15.9 to 21.8%. These findings demonstrate that BC aerogels prepared under optimized conditions (0.7% BC, pH 4, tert-butanol replacement) exhibit superior porosity, minimal shrinkage, and enhanced thermal stability. At the same time, the BC aerogels after replacement had excellent oil absorption performance, which can increase by 10.0–24.9%, compared with that of BC aerogels before replacement. This work provides a practical framework for developing eco-friendly, high-performance adsorbents.