Tuesday, May 3, 2011: 3:00 PM
Grand Ballroom B, 2nd fl (Sheraton Seattle)
The objective of this work was to evaluate the kinetic modeling of steam explosion and enzymatic hydrolysis reactions of sugarcane bagasse. It was proposed a first order kinetic for cellulose, hemicelluloses and lignin reactions during steam explosion at 165°C, 190°C and 210°C. A few studies have aimed the kinetics of lignin decomposition during steam explosion, then it was suggested a new mechanism for lignin reactions based on a simultaneous depolymerization and repolymerization in the lignin. The results showed that the quantity of lignin decrease until a certain reaction time and increase after this. Simulations of the kinetic models showed that the minimal lignin in pretreated bagasse occur with 14 min at 190°C, 5 min at 200°C, 1.2 min at 210°C and 0.8 min at 220°C. It was verified that these conditions is the same of the maximum enzymatic hydrolysis yield. The simulation of hemicelluloses hydrolysis model showed that sugars yield increase from 75% to 87% for 170°C and 220°C, respectively. The enzymatic hydrolysis of bagasse pretreated at 200°C for 5 min was modeling based on the Langmuir adsorption of cellulases and on Michaelis-Menten model for beta-glicosidase enzyme (BG). It was considered that the mechanism of inhibition by cellobiose and glucose were the competitive type. The results showed that the model had a good fit only for low levels of BG (< 10 U/g cellulose). These results suggest a non steady-state kinetic for cellobiose hydrolysis by BG at high level of this enzyme.