Imidazole as a new strategy in the lignocellulosic pretreatment: An application in corn sub-products with a focus on bioenergy production

To enhance the efficiency of pretreatment processes for lignocellulosic biomass, this study utilized the green solvent imidazole to pretreat residual corn biomass (corn straw (CS) and corncob (CC)) with a focus on cellulose recovery for ethanol production. The pretreatment involved varying temperatures (ranging from 120 to 180 °C) and times (30 and 60 min) with biomass:imidazole ratio of 1:9 (w.w−1). The effects of imidazole pretreatment on the biomasses were examined by analyzing the chemical composition, surface morphology, cellulose crystallinity, and compositional changes. The results demonstrated a significant alteration of the lignocellulosic complex due to imidazole pretreatment, resulting in a reduction of the lignin content, reaching 81.47 % and 74 % for CS (180°C-60min) and CC (180°C-30min), respectively. Moreover, the cellulose content in the pretreated solids increased by approximately 1.5 times compared to the raw biomass. The pretreated biomasses were subjected to enzyme hydrolysis (after pretreated at a higher temperature (150–180 °C)), which led to a high glucose yield. CC achieved a glucose yield of 100 %, while CS yielded 77 %. Alcoholic fermentation was carried out using Saccharomyces cerevisiae CAT-1, resulting in an ethanol yield of 82 % in 12 h for CC (180 °C for 30 min) and 66 % for CS (150 °C for 1 h).