Influence of Sulfuric Acid Pretreatment and Inhibitor of Sugarcane Bagasse on the Production of Fermentable Sugar and Ethanol

Abstract

Improper disposal of agricultural waste after harvesting season has posed serious health and environmental issues. Alternative methods to utilize agricultural waste to produce a value-added product, especially biofuel, have become the focus of research and industrial stakeholders. To make the process feasible, the maximum conversion should be achieved with the optimum operational condition. This research applied Response Surface Methodology (RSM) with the Box-Behnken design (BBD) to optimize sulfuric acid pretreatment of sugarcane bagasse by varying three pretreatment factors namely, acid concentration (0.5–3.5%), temperature (60–140℃), and time (20–100 min). Pretreated biomass was enzymatically hydrolyzed, and the effectiveness of pretreatment was examined according to the reducing sugar concentration. However, inhibitors namely, acetic acid, 5-hydroxymethylfurfural (5-HMF), and furfural were produced during pretreatment, which was analyzed through GC-MS analysis. The Box-Behnken design could optimize and correlate the effect of pretreatment parameters on the hydrolysis of sugarcane bagasse. The optimum pretreatment condition was predicted at an acid concentration of 3.50%, the temperature of 136.08℃, and the time of 75.36 min to obtain the maximum sugar production. Sugarcane bagasse pretreatment at optimum condition could produce a reducing sugar of 180.15 mg/g-sugarcane bagasse, which is 3.06 folds higher than untreated sugarcane bagasse. However, ethanol yield from pretreated biomass was less than unpretreated biomass because of the inhibitor formation. This study provides a new insight into utilizing agricultural waste in a more efficient and eco-friendly manner.