Pretreatment of corn stover for sugar production with switchgrass-derived black liquor

To improve the cost-effectiveness of biomass-to-sugar conversion, sodium hydroxide (NaOH) pretreatment of switchgrass was carried out at 21 °C using previously determined optimum conditions (2% NaOH (w/v), 6 h), and the spent alkaline liquid (black liquor) was collected and used for pretreatment of corn stover, a feedstock exhibiting a higher susceptibility to NaOH attack, for improved enzymatic hydrolysis at a reduced cost. The results showed that, because of the high pH and the appreciable amount of carbohydrates in the black liquor, sugar production during enzymatic hydrolysis of corn stover pretreated with black liquor was comparable to that of biomass pretreated with 1% NaOH. After black liquor pretreatment at the best residence time (24 h), the total reducing sugar, glucose, and xylose yields of corn stover reached 478.5, 287.7, and 145.3 mg/g raw biomass, respectively, indicating the viability of this novel pretreatment technology.