Estudo do processo organosolv aplicado ao bagaço de cana-deaçúcar para a geração de etanol de segunda geração

Abstract

Too high a rise in fossil fuel prices, coupled with its possible shortage, has provided a search for alternative fuels, with an increase in the production and use of biofuels, which can be generated from biomass. The biomass fibers of sugarcane are lignocellulosic, that is, they are composed of cellulose, hemicelluloses and lignin and have a complex structure, which hinders the separation of their sugars. Biomass must then go through three stages to produce second-generation ethanol: pretreatment, for the disassembly of fibers, enzymatic hydrolysis, the process in which enzymes "break" the sugars, and the fermentation, where these sugars are transformed into ethanol by yeast. Cellulose is one of the most interesting products and, when hydrolyzed, provides fraction rich in easily fermentable hexoses. However, it is protected by a barrier of lignin and hemicelluloses that hinders the action of microorganisms in their conversion to glucose monomers. The pretreatment steps, known as hydrolysis, aim to disintegrate the lignin-carbohydrate matrix and make the cellulose accessible to saccharification. Present work was developed, studying the influence of three variables in the stage of hydrolysis of the sugarcane bagasse by applying a factorial design 23, where the catalyst (X1), the solvent (X2) and the reaction time (X3) were the variables investigated. Organosolv pretreatment was replicated on the workbench, verifying its efficiency in the delignification of the lignocellulosic material, structures present in the biomass. The results show a significant influence of the studied variables on the glucose removal and may indicate a possible route for improvements in the experimental procedures for treatment of bagasse. The sulfuric acid catalyst and time of 90 minutes were significant in the delignification, a fact that was not observed in relation to the acetone and ethanol solvents. The solubilization of hemicellulose was better observed in the experiments where the sulfuric acid catalyst was used. The solvents acetone and ethanol, and time, did not present solubilization of hemicellulose. The solubilization of the cellulose requires a more robust model of experimental planning to verify the interactions of the process. The catalyst oxalic acid and time of 90 minutes, presented greater degradation of the lignocellulosic material, causing degradation products (acetic acid and furfural). The highest concentration of glucose occurred when the solvent used was ethanol, the sulfuric acid as the catalyst and the longer reaction time.