A clean and effective potassium hydroxide pretreatment of corncob residue for the enhancement of enzymatic hydrolysis at high solids loading

Abstract

Corncob residue (CCR) is an economic feedstock with enormous potential for the production of bioethanol. In this work, potassium hydroxide (KOH) pretreatment of CCR was investigated under relatively mild conditions, and the effectiveness of KOH pretreatment was evaluated by enzymatic saccharification at high solid loading. Results showed that after KOH pretreatment (16 wt% KOH dosage at 70 °C for 90 min) and the enzymatic hydrolysis at 20% solids loading and 20 FPU g⁻¹-substrate of cellulase loading, the glucose yield could reach up to about 91%, which was over 90% higher compared to the raw CCR without KOH pretreatment. Correspondingly, about 89% of lignin and 79% of extractives were removed after KOH pretreatment. In addition, the spent liquor of KOH pretreatment containing sylvite could be used as lignin-based fertilizer based on the concept of biorefinery. In this case, the entire process for the production of fermentable sugars was clean and sustainable, which is very vital for the conversion of lignocelluloses to bioenergy or chemicals.