A two-stage pretreatment using acidic dioxane followed by dilute hydrochloric acid on sugar production from corn stover

A two-stage pretreatment method was developed to improve sugar recovery in this study. Firstly, the corn stover was pretreated with acidic dioxane to remove lignin, then the residue was subjected to dilute hydrochloric acid to eliminate the negative effects of hemicelluloses on enzymatic hydrolysis as well as increasing xylose yield. The optimal condition was 90 degrees C, 20 min, and 9/1 (v/v) dioxane-water including 1.0 wt% HCl solution in the first stage followed by 120 degrees C and 40 min for 1.0 wt% dilute hydrochloric acid in the second stage. The total yields of glucose and xylose were 91.5% and 79.7%, respectively, with a low cellulase dosage of 3 FPU g(-1) of substrate. This two-stage pretreatment was effective due to the removal of lignin in the first stage and the hydrolysis of hemicelluloses in the second stage, resulting in a very high sugar recovery with a low enzyme loading.