Combination of deep eutectic solvent and diluted acid pretreatments for sugarcane bagasse fractionation

The worldwide crisis of the fossil fuels and the current environmental issues have led for the search of new alternative for the energy industrial sector. In this scenario, the production of second-generation ethanol, from the exploitation of lignocellulosic biomasses fractions, has presented itself as a prominent alternative. Thus, the present work aimed to develop a combined process for the sugarcane bagasse (SCB) fractionation using a deep eutectic solvent (DES), a new class of ecofriendly solvents, and diluted acid hydrolysis. The DES delignification process was able to reduce the SCB lignin content in about 48% and, at the optimum hydrolysis conditions (1.1% v v⁻¹ of sulfuric acid and 59 min of hydrolysis time), the delignified material was converted into a solid fraction rich in cellulose (51.11 ± 0.95%, increment of 41.46%) and into a liquor product rich in xylose (18.26 ± 3.14 g L⁻¹). The data statistical analysis proved that the combined strategy was superior to the single and direct acid hydrolyzation of SCB. The structural changes of the material after all investigated pretreatments were confirmed by FTIR and DRX techniques, what reinforce the relevance of the results here reported.