Efficient enzymatic hydrolysis of active oxygen and solid alkali/dilute sulfuric acid-pretreated corn cob

Abstract

This work proposed a two-step pretreatment method of cooking with active oxygen and solid alkali (CAOSA) followed by dilute sulfuric acid treatment (DA), to contribute enzymatic hydrolysis of corn cob. The first step, CAOSA pretreatment, removed 83.16 % of the lignin, while the second step, a milder pretreatment with DA further eliminated hemicellulose. After the two-step pretreatment, the cellulose content of the residue reached 66.74 %, and with a solid loading of 5 %, the glucose yield was remarkably high at 98.35 % with a concentration of 36.47 g/L. The optimal conditions of the process were determined as follows: DA with 1 % H2SO4 at a solid-to-liquid ratio of 1:10, a temperature of 110 ℃, and a pretreatment time of 60 min. To confirm the efficacy of the two-step pretreatment, we characterized the samples treated with different methods using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The developed method proposes an effective pretreatment and results in the complete enzymatic hydrolysis of corn cob.