Effect of Organic Acid Pretreatment on Napier Grass (Pennisetum purpureum) Straw Biomass Conversion

Production of specialty chemicals or bioproducts from lignocellulosic biomass has a major bottleneck at hydrolysis step due to recalcitrant structures of lignocellulose fibrils. Pretreatment is necessary to be executed to enhance saccharification efficiency. This study, the effect of acid pretreatment on lignocellulosic conversion of Napier grass was evaluated based on Response Surface Methodology (RSM). Pretreatment conditions were optimized for oxalic, citric, acetic, and hydrochloric acids. Validation indicated that the models were predictive to magnify the conversion. Hydrochloric acid exhibited highest effectiveness, followed by oxalic, acetic, and citric acids. The optimal conditions were using 0.7% (w/v) hydrochloric acid at 105°C for 60.18 min and using 5.72% (w/v) oxalic acid at 104.66°C for 76.94 min. The obtained sugar yields were low compared to those from rice straws pretreated with the optimal, same acid conditions. The results here suggested the requirement of optimization study before choosing organic acid pretreatment to different types of lignocellulosic biomass.