Sequential dilute acid and alkali pretreatment of corn stover: Sugar recovery efficiency and structural characterization

• A sequential dilute acid–alkali pretreatment for corn stover is designed.
• This pretreatment does not require detoxification methods prior to fermentation.
• High overall glucose yield is obtained with enhanced enzymatic digestibility.
• Structural changes in corn stover are critical to enhanced enzymatic digestibility.

The objectives of this study were to explore the feasibility of applying sequential dilute acid and alkali pretreatment into the hydrolysis of corn stover and to elucidate the effects of structural changes in the biomass on its enzymatic digestibility. H2SO4 used in the first step selectively hydrolyzed 74.6–77.3% of xylan and NaOH used in the second step removed 85.9–89.4% of lignin, from the raw corn stover. Compared to single dilute acid pretreatment, the proposed combined pretreatment minimized the generation of byproducts such as acetic acid, furfural and hydroxymethylfurfural in the hydrolysates, and enhanced the enzymatic hydrolysis of the solid residue. The changes in the structural features (porosity, morphology, and crystallinity) of the solid residue were strongly correlated with the enhancement of enzymatic digestibility. The overall glucose and xylose yields finally obtained after enzymatic hydrolysis reached 89.1–97.9% and 71.0–75.9%, respectively.

Figure optionsDownload as PowerPoint slide