Pretreatment of corn cobs using hydrogen peroxide-microwave assisted to enhance enzymatic hydrolysis: Kinetics studies

This study used two-step pretreatment, including hydrogen peroxide (HP) followed by microwave-assisted (HPMA) to enhance enzymatic hydrolysis of corn cobs. Initial stage, namely HP pretreatment eliminated 57.78 % of lignin, while in the next stage, the cellulose content of the solid phase was 58.28 %. The optimal conditions of HP procedure were established at 80 °C for 50 min and the process was continued for 50 min in microwave. The effectiveness of the pretreatment was analyzed by the procedures including XRD, FT-IR spectroscopy, and SEM. The results showed that the proposed method offered an efficient pretreatment and achieved complete enzymatic hydrolysis of corn cobs. The kinetic parameters were found by comparing the laboratory data with cellulose saccharified to generate sugars. Furthermore, HPMA demonstrated an activation energy of about 3.9641 kJ mol−1 and the CMCase and FPase activity was determined to be 371.483 and 354.530 U mL−1, respectively. The Michaelis-Menten constant ranges from 0.0127 to 0.0253 and the vmax is between 1.08 × 10−7 - 3.77 × 10−7 Mol L−1 s−1, indicating cellulase catalyzes corn cob cellulose conversion into sugar. The maximum level of total reducing sugars reached 15.46 g L−1, achieved using an enzyme content of 50 % (v/w) at hydrolysis period of 30 h.