FeCl3 catalyzed organosolv pretreatment combined with additive to enhance fed-batch enzymatic hydrolysis of corn stover at high solid loading

Abstract

This study focused on exploring the optimal pretreatment conditions of FeCl₃-catalyzed organosolv pretreatment by response surface methodology (RSM) and adding additives to reduce the adverse impact of lignin, thus boosting the enzymatic hydrolysis of corn stover. Results showed that the optimum glucose yield after 24 h (29.8 g/100 g raw material) was achieved at 175.9 °C, 19 min with 77.7 mmol/L FeCl₃ catalyzed organosolv pretreatment, representing 87.4% of total glucose in native corn stover. This enhancement was attributed to the structure alteration, which removed ~ 100% hemicellulose and 83.5% lignin. Furthermore, the influence of different additives on enzymatic hydrolysis was investigated, and the results suggested that Tween 80, PEG 6000, pepton and calcium lignosulfonate (CL) exhibited superior performance in improving glucose yield under low-solid and high-solid loading enzymatic hydrolysis. With the addition of PEG 6000 under 1/2 reduced enzyme loading, the highest glucose yield at 2% (w/v) and glucose concentration at 30% (w/v) reached 87.9% and 181.4 g/L (involving 8.3 g/L oligomer glucose), respectively. Further prolonging the hydrolysis time, the increased glucose yields with additives were strengthened, especially in enhancing the oligomer glucose during high-solid loading enzymatic hydrolysis.