Enhanced digestibility and fermentability of sugarcane bagasse in biofuel production by surfactant-assisted dilute acid pretreatment

Abstract In this study, various combined pretreatment strategies using liquid hot water (LHW), 60 % ethanol, 1% H2SO4 and 0.5 % NaOH together with different surfactants (PEG 6000, Triton X-100 and Tween 80) were evaluated to improve glucose production from sugarcane bagasse (SCB) during enzymatic hydrolysis. After pretreatment with PEG 6000-assisted 1% H2SO4, the highest glucose yield of 75.04 % was achieved. Pretreatments of SCB with various combinations of H2SO4 (1–3%, w/v) and PEG 6000 (0–1.5 %, w/v) were further investigated for enhancing enzymatic hydrolysis and ethanol production. When 1.5 % PEG 6000 was introduced during pretreatment with 2 % H2SO4, the highest glucose yield of 86.14 % and ethanol concentration of 20.17 g/L were liberated, which were much higher than those obtained from pretreatment with 2% H2SO4 alone. This increased digestibility and fermentability can be attributed to decreases in crystalline sizes and PEG 6000 adherence to SCB surfaces, which was confirmed by cellulase adsorption isotherms, FT-IR, XRD, and SEM analysis. In addition, prehydrolysate and the stillage remaining after ethanol production were sequentially digested to seek potential biomethane production and resulted in final methane yields of 264.05 mL and 387.77 mL per g of volatile solids, respectively. The feasibility of the process provids an environmentally friendly technology for an integrated biorefinery.