SEQUENTIAL AUTOHYDROLYSIS–ORGANOSOLV PRETREATMENT FOR CELLULOSE EXTRACTION AND CHARACTERIZATION FROM SUGARCANE BAGASSE

Introduction: Sugarcane bagasse (SCB) is an agro-industrial waste with high lignocellulosic content and a good source to produce cellulose due to its renewability, sustainability and availability. The objective of this work is to maximize cellulose concentrations using autohydrolysis, organosolv and bleaching processes. Methodology: Autohydrolysis was performed in a 190 mL stainless steel batch reactor under different operating conditions using a central composite design (170, 180, 190 °C for 30, 40, 50 min) in a biomass–liquid ratio of 1:10 (w/v) with particle size of 0.5 - 2.0 mm. Delignification was then carried out using an organosolv of 40% (v/v) ethanol and 0.1 % (w/v) NaOH at 180 °C for 20 min. The delignified SCB was then bleached with 1% (v/v) H₂O₂ and 1% NaOH (w/v) at 80 °C for 1 h. The untreated SCB and delignified and bleached sugarcane bagasse (BSCB) were subjected to characterizations such as quantitative acid hydrolysis, Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction. Results and discussions: The chemical analysis of untreated SCB revealed 33.13 ± 0.30 % cellulose, 15.13 ± 0.08 % hemicellulose and 28.60 ± 2.23 % lignin content, and after autohydrolysis at 190 °C/50 min, the highest cellulose value of 67.90 ± 0.27 % was shown, while hemicellulose and lignin contents decreased and increased, respectively, due to the solubilization of hemicellulose into the liquid phase, leaving lignin and cellulose concentrated in the solid phase. The cellulose content increased to 79.4 ± 0.25 % in the delignified SCB and 97.79 ± 0.20 % in the BSCB. The FTIR spectrum of the BSCB shows characteristic peaks similar to those of commercial cellulose. The crystallinity index increases from 52.2 % of the untreated SCB to 70.7 % of BSCB. Conclusion: Autohydrolysis and organosolv sequential process are eco-friendly and effective methods for SCB fractionation to obtain cellulose.