Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
With present global concerns on climate change, food-fuel competition, and secure access to energy, intense research is devoted to lignocellulose conversion into biofuels. Sugarcane bagasse and straw are particularly promising due to synergies with the sugarcane-based bioenergy system. However, the incomplete understanding of lignocellulose structure and its recalcitrance limit the process optimization. For this reason, the aim of this study was to evaluate the decrease of cellulose crystallinity after the prehydrolysis (hydrothermal and steam explosion) and soda delignification of sugarcane straw and bagasse using a new methodology. During each stage of treatment, raw and treated materials were characterized by X-ray diffraction, as well as by chemical analysis and SEM micrographs. The results showed that during the whole process there was a large decrease in cellulose’s crystallinity, measured considering the mass loss in each component. An expressive decrease of 34.9% in the cellulose crystalinity was obtained for straw after steam explosion pretreatment and soda delignification. Concerning the bagasse, the loss was 30.5% after hydrothermal pretreatment followed by soda delignification. As the goal of the stages of pre-treatment and delignification is to increase the pore size and reduce the crystallinity of cellulose, in order to improve accessibility to the cellulose fibers, this purpose was reached for both biomasses and the mentioned steps of treatment. After the treatments, measured crystallinity indicated partial cellulose decrystallization or formation of more defective crystallites. [Acknowledgements due to FAPESP, CNPq, DAAD and CAPES]