Effects of water content on ball milling pretreatment and the enzymatic digestibility of corn stover

Abstract

Lignocellulosic biomass pretreatment is a key step to determine the efficacy of biofuel production because of the recalcitrance of lignocellulosic feedstock. The effects of various water inputs, i.e., 0, 25, 100, and 400% (w/w), on the ball milling pretreatment of corn stover and enzymatic hydrolysis were studied under two milling temperatures (80 °C and 100 °C) and three milling times (10, 20, and 30 min). Ball milling reduced corn stover particle size and disrupted the rigid cell wall matrix. As milling time increased, corn stover size decreased remarkably. Changes in corn stover were analyzed using size distribution graphs and geometric mean diameter with respect to milling temperature and time. Milling with 0% (w/w) water resulted in the rapid grinding of corn stover. The highest glucose yield (66.96%) was obtained after milling at 80 °C for 30 min with no water. The corn stovers milled with 0% or 25% (w/w) water showed higher glucose yields when milled at 80 °C than at 100 °C, while the samples milled with 100% or 400% (w/w) water showed higher glucose yields at 100 °C. Finally, several ball milling conditions were proposed to construct a combinational pretreatment process based on the study results. These results provide a basis for minimizing water use during lignocellulosic biofuel production and improving sustainability. Keywords: Ball mill pretreatment, Physico-chemical pretreatment, Biofuel, Biorefinery, Corn stover