Subcritical Water Hydrolysis Pretreatment of Sugarcane Bagasse to Produce Second Generation Ethanol

Abstract Subcritical water hydrolysis (SWH) is a promising pre-treatment process for the production of second-generation ethanol (2 G ethanol), furthermore subcritical water is a fast, non-toxic, and green process. To address this issue SWH was performed at follow conditions: 200 °C, 15 MPa, 20 e 5 mL min–1; the hydrolysate was obtained in order to produce a fermentable liquor in three different steps, 1) pure SWH, 2) SWH concentrated and rotary evaporator, and 3) SWH combinated with enzymatic hydrolysis. S. cerevisiae SA-1 and the pentose metabolizing yeast, S. stipitis NRRLY-7124, were used to evaluate fermentation potential. The combination of the products of SWH and the integration of enzymatic hydrolysis provided the greatest fermentable sugar yield with 3.0 ± 0.53 g L–1 xylose and 6.3 ± 0.5 g L–1 glucose; subsequent fermentation with S. cerevisiae SA-1 and S. stipitis NRRLY-7124 resulted in a 2 G ethanol yield of 2.20 ± 0.01 g L–1.