Combination pretreatment of steam explosion and NaOH enhances enzymatic saccharification of corn stover

Abstract

The presence of lignin sheaths and the crystalline structure of cellulose are two key barriers in the development of corn stover (CS). To remove these two barriers and improve the digestibility of carbohydrates in CS, CS (pretreated by H 2 O 2 , H 2 SO 4 , NaOH, an enzyme, steam explosion [SE], and SE combined with NaOH [SE-NaOH]) was hydrolyzed. The total reducing sugar yield (Y trs ), accessibility of the enzyme to the substrate (K obs,0 ), and gradual loss of the enzyme activity (K i ) were compared by regression analysis of the kinetic model, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The pretreatment dramatically increased the Ytrs and K obs,0 , and remarkably decreased the K i . The maximum increase in the Y trs (106.57%) was obtained after the saccharification reaction of the CS pretreated by SE-NaOH. Physicochemical characterizations of the CS pretreated by SE-NaOH showed that the SE-NaOH pretreatment effectively reduced the lignin sheath, decreased cellulose crystallization, and created favorable conditions for enzymatic diffusion and penetration.