Dilute acid pretreatment, delignification and enzymatic hydrolyzes of sugarcane bagasse for bioethanol production

Three main interests have motivated the recent wave of policies encouraging biofuel production and use. Concern over greenhouse gas emissions raised interest in biofuels as a climate change mitigation strategy; fluctuating oil prices; and a desire for economic growth in the agriculture sector supported investment in biofuels as a rural development strategy. Among many possible alternatives the bioethanol from sugarcane has been recognized as sustainable one and many efforts are nowadays in course to develop the second generation bioethanol using sugarcane bagasse as feedstock. Bearing all this in mind, in this study sugarcane bagasse was submitted to a chemical pretreatment with dilute sulfuric acid (1 % v/v H₂SO₄), and then delignificated with alkaline solution with concentration of NaOH about 0,5 % w/v, 80 °C and  90 min reaction time, both with 20 % w/v solids loadings. After that, the samples were submitted to enzymatic hydrolyzes with 8,0 % w/v solids loadings (dry basis) considering 15 FPU and 33,0 CBU per gram of dry biomass, for 72 hours. It follows that the delignification process used in this work was efficient, since the cellulose values were high and there was a lignin removal, compared to the raw sugarcane bagasse. The enzymatic hydrolysis process favors the release of fermentable sugars, given the fact the values for the concentration of total reducing sugars increases as the hours of hydrolysis process passes. However, it is shown that in 24 hours of hydrolysis occurs the maximum liberation of sugars.