Enzymatic Hydrolysis Exploration and Fermentation: Acid Pretreatment and Delignification in Sugarcane Bagasse for 2G Ethanol Production

Renewable energy is described in the political sphere as a means to reduce greenhouse gas emissions and simultaneously increase energy security, especially in the transport sector, which is dependent on oil products. Enzymatic hydrolysis is an intermediate step in the biomass conversion process into fermentable sugars. This step has to be favorable to produce high sugar yields and the resulting hydrolysate must be able to support fermentative organisms while they produce biofuels. In this investigation sugarcane bagasse was submitted to a chemical pretreatment with dilute sulfuric acid (121 °C, 80 min and 1.0 % v/v H2SO4) and then delignification with alkaline solution (80, 100 and 120 °C, 30, 60 and 90 min, 0.5, 1.0 and 1.5 % w/v NaOH) both with 20 % w/v of solids loading. The samples were submitted to enzymatic hydrolysis with 8.0% w/v solids loading (dry basis) considering 15 FPU (filter paper unit) and 33.0 CBU (beta-glucosidase unit) per gram of dry biomass. The fermentation was applied on the 0.5 % w/v NaOH, 80 °C, 90 min delignificated point. The enzymatic hydrolysis process favored the release of fermentable sugars, given the fact the values for the concentration of total reducing sugars increases with hydrolysis time. However, it is shown that after 24 h of hydrolysis occurs the maximum liberation of sugars. Results from fermentation process showed that YP/GLC for pretreated sugarcane bagasse was about 0.51 kgetanol/kgGLC and for the delignificated was 0.47 kgetanol/kgGLC. It was attained a process yield of 100 % for the pretreated sugarcane bagasse and 91.59 % for the delignificated.