Process optimization for acidic deep eutectic solvent pretreatment of corn stover to enhance enzymatic saccharification

In the present study, deep eutectic solvent (DES) was employed for an effective pretreatment of recalcitrant corn stover (CS) to improve the efficiency of the subsequent saccharification process. Accordingly, the molar ratios of lactic acid (LA)/choline chloride (ChCl), temperature, and time were studied via response surface methodology to optimize pretreatment conditions. While the best cellulose and hemicelluloses digestibility (94.85%) and delignification (29.27%) efficiency were achieved using the LA/ChCl molar ratio of 1 at 140 degrees C after 4 h. Overall, this efficiency was nearly seven-fold higher when compared to the untreated CS. Besides, at higher temperatures (> 140 degrees C), the humins were generated in the pretreatment process, which might have wrapped around the surface of the pretreated CS and resulted in an impeded enzymatic accessibility. The pretreatment efficiency was also fully maintained after three repeated cycles. This study provides an insight into the comprehensive utilization of the LA/ChCl type of DES for robust lignocellulosic biomass pretreatment.