Kinetic study on enzymatic hydrolysis of rice straw with ultrasound-assisted pretreatment

Key words: 
• ultrasound-assisted pretreatment /
• kinetics /
• cellulose

Abstract: In this work, the effect of ultrasound-assisted pretreatment on rice staw was investigated under the condition of 120 W, 30 min, and a simplified kinetic model fitted for the straw enzymatic-saccharification was established to evaluate the pretreatment efficiency. The results showed that most of the hemicellulose and lignin were effectively removed after pretreatment, and the ultrasound-assisted pretreatment was more efficient than the alkali-pretreatment or acidpretreatment alone. The validity of the model developed was confirmed by successfully simulating the time course of saccharification. The values of K, KM, KI for alkali preteatment, ultrasound-assisted pretreatment, acid pretreatment, ultrasoundassisted pretreatment were 15.30，21.32，13.40 and 15.42 h-1; 17.55, 14.14, 15.29 and 15.08 g/L; 2.31, 2.08, 1.81 and 1.85 g/L, respectively. Ultrasound-assisted pretreatment could effectively increase the lignin degradation by decreasing the crystallinity of lignocellulose as destroying the intermolecular hydrogen bonding. Thus it may improve the availability of zymohydrolysis and ultimately increase the saccharification rate.