Evaluation of an Integrated Fractionation Approach for High-Purity Cellulose Fiber Production from Sugarcane Bagasse
The extensive use of synthetic polymers has raised significant environmental concerns due to their non-biodegradable nature and persistence in the environment. Cellulose-based materials have attracted considerable interest owing to their excellent inherent properties which enable their wide range of industrial and biomedical applications. In this study, an integrated approach (hydrothermal process, organosolv delignification and chlorine-free bleaching) was evaluated to obtain high-purity cellulose fiber from sugarcane bagasse (SCB). The untreated SCB was first subjected to hydrothermal process under varying experimental conditions defined by a central composite design (170–190 °C, 30–50 min) using a solid-to-liquid ratio of 1:10 (w/v). The hydrothermally pretreated solid was subsequently delignified using an organosolv process with an aqueous solution of 40% (v/v) ethanol and 0.1% (w/v) NaOH at 180 °C for 20 min. Finally, the organosolv delignified SCB was bleached with 1% (v/v) H2O2 and 1% NaOH (w/v) at 80 °C for 1 h. The bleached cellulose fiber exhibited a composition of 97.79 ± 0.19% cellulose, 1.10 ± 0.14% lignin and 0.23 ± 0.13% hemicellulose. XRD analysis displayed a notable increase in the crystallinity index from 52.2% in untreated SCB to 70.7% in the bleached cellulose fibers (BCF). Furthermore, FTIR revealed the disappearance of characteristic lignin and hemicellulose peaks at 1729, 1602, 1512 and 1240 cm−1 while the intensity of cellulose bands including the crystallinity-associated peaks at 1432 and 1320 cm−1 were preserved. The SEM images further confirmed significant transformation with distorted vascular tissue and exposed cellulose fibrils indicating extensive defibrillation.