Conversion of cashew apple bagasse into ultralight cellulose cryogels: Structure-property relationship affected by...

This study examines converting cashew apple bagasse into ultralight cellulose cryogels and assesses how defatting pre-treatment affects the structure-property relationship. The alkaline extraction purified the biomass, raising cellulose content from 24.16% to about 70-74%. FTIR and TGA analyses confirmed the removal of non-cellulosic fractions and enhanced thermal stability, with the main thermal degradation peak occurring around 330 °C. The cryogels exhibited extremely low densities (0.018-0.020 g cm^-3). Microstructural analyses by CLSM and SEM showed lipid removal (LF-CBC) led to a finer, more homogeneous, highly interconnected fibrillar structure network. At the same time, the presence of residual hydrophobic components (CBC) served as a natural structural reinforcement, increasing mechanical stiffness and resistance to pore collapse under compression. Sorption properties were strongly governed by microstructure: LF-CBC showed greater affinity for liquid water, associated with increased surface hydrophilicity, while both cryogels exhibited high oil sorption capacity (up to 36 mL g^-1). XRD analysis confirmed the preservation of the crystalline structure of cellulose (type I), with crystallinity indices of 46-48%. Furthermore, the cryogels showed strong structural integrity in water without synthetic additives. This suggests cashew apple bagasse is a promising, sustainable resource for producing advanced porous biomaterials, aligning with circular economy principles.