Pretreatment of Corn Stover for Sugar Production with Combined Alkaline Reagents

Corn stover pretreatment using a combination of sodium hydroxide (NaOH) and calcium oxide (CaO) at room temperature was investigated for improved cost-effectiveness of biomass-to-sugar conversion in this study. The effects of NaOH loading, CaO loading, and residence time on enzymatic hydrolysis were studied, and the total reducing sugar yield in the enzymatic hydrolysis was used to evaluate the pretreatment conditions, Compared with NaOH pretreatment, pretreatment with the combination of NaOH and CaO resulted in a similar sugar production rate but at a potentially lower cost. The addition of CaO not only increased the alkalinity, which favored biomass digestibility improvement, but also contributed to better biomass preservation in the pretreatment. On the basis of the sugar production rate and cost-benefit considerations, the two recommended pretreatment conditions were 3 h, 0.05 g NaOH g(-1) raw biomass, 0.1 g CaO g(-1) raw biomass and 6 h, 0.05 g NaOH g-1 raw biomass, 0.05 g CaO g-1 raw biomass, at which the total reducing sugar yields were 529.0 and 538.9 mg g(-1) raw biomass, respectively, with overall carbohydrate conversions of 75.6 and 77.0%, respectively.