Cellulose Accessibility and Zeta potentials of Sugarcane Bagasse Pretreated by Green Liquor and Ethanol for High Hydrolysis Efficiency

Green liquor (GL) combined with ethanol (GL-ethanol) was selected to pretreat sugarcane bagasse (SCB). The results showed that the maximum lignin removal of 85.2% was achieved at 160 °C and a GL loading of 1.5 mL/g-dry substrate. The glucose yield of pretreated SCB increased with increased pretreatment temperature, and the maximum glucose yield of 97.7% was reached from SCB pretreated at 160 °C. Simons’ stain (SS) showed that the glucose yield was affected by cellulose accessibility instead of lignin content when lignin removal was > 70%. The cellulase adsorption isotherm fitted by the Langmuir model showed that the strength of interaction between the cellulase and substrate of GL-ethanol-100/1.5 (100 °C, 1.5 mL GL/g-dry substrate) was declining with increased pH. The adsorption was pH-dependent, and negatively controlled by the pH value. Electrostatic interactions can account for the pH-dependency of cellulase adsorption.