Ultralight biomass-based carbon aerogel with hierarchical pore structure fabricated using unidirectional freeze casting and potassium hydroxide activation

Abstract

A low-cost biomass carbon aerogel with a hierarchical pore structure (BCA-H) was prepared from straw using unidirectional freeze casting and potassium hydroxide (KOH) activation. The morphology, microstructure, and properties of the material were investigated. The hierarchical pore structure is a three-dimensional structure consisting of micropores, mesopores, and macropores. The material exhibits an ultra-low density (0.038 g/cm3), as well as a high porosity (98.2 %) and specific surface area (1531 m2/g). After hydrophobic modification, the contact angle of the sample with water was 169.5°, and its adsorption capacities for acetone and rapeseed oil were 29 and 33 times its mass, respectively. The material has promising prospects in adsorption technology, such as for organic solvent adsorption and oil–water separation.