Abstract

Bioethanol production from wheat straw (37.7% cellulose, 20.5% hemicelluloses, 11.5% lignin, 10.5% ash, 4.5% proteins, 2.2% silica, 4.5% extractives) was evaluated. Pretreatment of the material with H2SO4 at different concentrations (0.1 to 0.7 %p/p) and temperatures (140 to 200°C) was evaluated by the glucose yield in enzymatic hydrolysis. The best yields of glucose (60.6% to 71.5%) and low inhibitors formation were obtained with 0.2% H2SO4. The variables time and temperature in the pretreatment (0.2% H2SO4) were optimized by a 22 full factorial central design. The response was the ethanol yield in simultaneous saccharification and fermentation (40°C, 72 h, 15UPF of cellulose, 15 IU of ?-glucosidase, 6 g/L yeast). The data were analyzed by the Modde 7.0 software. The variables were coded and normalized in unitary values -1 (6 min; 175°C) and +1 (30 min; 200°C). The best results were obtained at 205C for 18 minutes. The ethanol yield was 84% with a concentration of 29 g/L.