Statistical optimization of aqueous ammonia pretreatment and enzymatic saccharification of corn stover for enhancing sugars production

Abstract

Response surface methodology (RSM) was adopted to optimize aqueous ammonia pretreatment and enzymatic saccharification of corn stover for enhancing sugars production, respectively. Pretreatment variables including pretreatment temperature, aqueous ammonia concentration and pretreatment time and saccharification variables including reaction time, enzyme loading and biomass loading were successfully found to have significant effects on sugars yields. Results indicated that corn stover powder (CSP, particle size < 0.3 mm) pretreated using 13.2 wt % aqueous ammonia solution at 70.0 °C for 7.9 h along with 20.0% ( w/v ) of solid loading was suitable to be applied to saccharification. The optimized pretreatment conditions could result in 98.3% of cellulose recovery, 86.5% of hemicellulose recovery and 60.7% of lignin removal, respectively. After optimization of enzymatic saccharification, maximum yields of reducing sugar (728.33 mg/gds) and xylose (290.43 mg/gds) along with 93.8% of holocellulose conversion and 80.6% of hemicellulose conversion could be obtained while the pretreated CSP was saccharified at 50.0 °C, pH 4.8 for 37.6 h by adopting 12.3 FPU/gds of enzyme loading, 7.6% ( w/v ) of biomass loading and 0.5% ( w/v ) of Tween-80, respectively. This is the first report about systematic optimization of aqueous ammonia pretreatment and enzymatic saccharification of CSP using self production cellulases for enhancing sugars yields in one study. • Aqueous ammonia pretreatment of corn stover was statistically optimized. • Enzymatic saccharification of aqueous ammonia pretreated corn stover was optimized. • Cellulose recovery (98.3%) and hemicellulose recovery (86.5%) were obtained. • Conversions of holocellulose (93.8%) and hemicellulose (80.6%) were obtained.