Tuesday, May 3, 2011
New technologies to enable the replacement of petroleum by fuels from renewable source have relevance in the current energy scenario. In this context, the use of sugarcane bagasse becomes interesting for ethanol production and contributes to sustainability and energy security. In this work the influence of the hydrothermal pretreatment on enzymatic hydrolysis and structure of lignin obtained during delignification process was evaluated. These analysis contribute to biorefinary concepts aimed the utilization of cellulose and lignin as raw material for production of valuable products. The hydrothermal pretreatment was carried out in different conditions of temperature (180 and 190◦C) and time of reaction (10,20,30,40 and 50 min). The materials were submitted to a fixed delignification condition (1% (m/v) NaOH, 1h at 100◦C). Lignin was analysed by small angle X-ray scattering for gyration radii determination and the fractal analysis. Delignified bagasse was subjected to enzymatic hydrolysis with 3 mg of Accelerase 1500/g of substrate, pH 5 for 72 h at 50◦C. The result reveal that the sample pretreated and delignified had at least 60% increase in the enzymatic hydrolysis compared with bagasse in natura. Bagasse pretreated at 180◦C for 20 min presented the better performance during the enzymatic hydrolysis considering the lower losses of cellulose and the higher conversion into glucose (90%). Lignin showed a mass fractal feature and an expressive polydispersity observed in gyration radii values. Only at high severity it is possible to observe an influence of pretreatment on lignin obtained, which presents a further fragmentation and porosity.