Two-Stage Fractionation of Sugarcane Bagasse by a Flow-through Hydrothermal/Ethanosolv Process

This work aimed to study the fractionation of sugarcane bagasse using a two-step hydrothermal and ethanosolv process in a flow-through reactor system. The effects of reaction temperature with or without acid addition were studied based on the removal, recovery, and yield of biomass components in both solid and liquid phases. Increasing the temperature from 150 to 190 °C with H2SO4 adjusted to pH 2 in the first hydrothermal step followed by the ethanosolv step using a mixture of ethanol:water (95:5 v/v) for 48 min with a constant flow rate of 25 mL/min led to increasing trends of hemicellulose and lignin removal in ranges of 79.1–98.5% and 62.4–95.6%, respectively, while a decrease in the remaining cellulose residues in the range from 87.8 to 40.5% was observed. This corresponds to yields of hemicellulose and lignin obtained in the liquid phase being in ranges from 42.9 to 63.8% and from 44.2 to 61.0%, respectively. Operation at 170 °C with acid supplementation in the hydrothermal step followed by an ethanosolv process was found to be the optimal conditions for the efficient removal of hemicellulose and lignin with high cellulose recovery. The developed process can be applied for efficient fractionation of bagasse in biorefineries.