Process optimization for deep eutectic solvent pretreatment and enzymatic hydrolysis of sugar cane bagasse for cellulosic ethanol fermentation

Abstract This study investigated cellulosic ethanol production from sugar cane bagasse (SCB) pretreated by triethylbenzyl ammonium chloride/lactic acid (TEBAC/LA) deep eutectic solvent (DES). The results showed that the pretreatment of SCB with TEBAC/LA DES at 120 °C for 4 h with 1:15 (solid to liquid ratio) resulted in the best cellulose digestibility (88.23 ± 1.24%), which was approximately 228% higher than that of untreated SCB. Furthermore, the maximum cellulosic ethanol concentration of 16.84 g/L was achieved using glucose (36.06 g/L) and xylose (7.36 g/L). Moreover, the ethanol productivity and yield were 0.70 g/(L·h) and 0.42 g/g fermentable sugar, respectively. The efficient bioconversion was ascribed to the remarkable delignification (88.72 ± 1.63%), xylan removal (73.93 ± 0.17%), along with optimum cellulose recovery (95.89 ± 1.54%). Importantly, the enzymatic hydrolysis digestibility remained unchanged after 5 times DES recycling process. Overall, it also provided an insight into the efficient SCB biorefinery of DES systems.