Effect of Hot Water Pretreatment Severity on the Degradation and Enzymatic Hydrolysis of Corn Stover

The effects of hot water pretreatment on the degradation and enzymatic hydrolysis of corn stover were studied. Nearly 100% cellulose recovery in the solid fraction was obtained when corn stover was pretreated at 170C to 210C for 3 to 10 min. The highest pretreatment severity of 4.239 (210C, 10 min) resulted in the highest solid solubilization (37.0%) and xylan solubilization (90.5%). At this severity, inhibitors such as acetic acid, furfural, and hydroxymethyl furfural (HMF) also reached the highest levels of 7.1, 4.6, and 0.6 g L-1, respectively. When the pretreatment temperature was less than 190C, the furfural concentration was below 1.0 g L-1 and no significant levels of HMF were detected. Enzymatic hydrolysis results showed that increased glucose yields were obtained with increased pretreatment temperatures of corn stover. The highest glucose yield of 89.2% was obtained at the pretreatment severity of 3.716 (210C, 3 min). Due to the degradation of sugars, a glucose yield of 85.9% was obtained at the highest pretreatment severity of 4.239 (210C, 10 min).