Organosolv delignification of sugarcane bagasse combined with physical-mechanical processes

Abstract

The production of biofuels from vegetal raw materials can be performed by different technological routes. Currently, bioethanol stands out from the alternatives for the production of liquid biofuels and requires the use of agricultural residues that contain significant amounts of polysaccharides (e.g., sugarcane bagasse). For this, it is necessary that the lignocellulose associative structure present in these materials is submitted to pretreatment steps in order to effectively separate (in a selective and efficient form) the major components (cellulose, lignin and hemicelluloses). In order to obtain bioethanol from the cellulosic fraction, bottlenecks such as the amount of residual lignin and hemicelluloses and cellulose crystallinity can limit the effectiveness of enzymatic hydrolysis and fermentation steps. In this context, kinetic studies in the pretreatment step are of extreme importance to quantify the acceptable amounts of residual hemicelluloses and lignin in the pulps obtained. Aiming at applying the advantages presented by the organosolv process, this project proposes two comparative routes: the kinetic study to remove the hemicellulose fraction (hydrothermal process) followed by the kinetic study of organosolv delignification, and the kinetic study of organosolv delignification without the hydrothermal step. Both routes will be performed using a microwave digestion system for the pretreatment of the sugarcane bagasse fibers. This can enhance the efficiency of hemicellulose and lignin removal in inferior time if compared to conventional extraction processes. After the pretreatment step, cellulosic pulps will be submitted to physical-mechanical treatments (refining, milling, and atmospheric plasmas) in order to reduce the crystallinity of cellulose and to improve the access to enzymatic hydrolysis. The success of the treatments will be assessed using enzymatic and acid hydrolysis standard protocols. (AU)