Mixed Acid-Catalyzed Hydrolysis (MACH) of Waste Distiller's Grains (WDG) for Production of Fermentable Sugar

Abstract

Waste distiller's grains (WDG),a co-product of brewing industry, was an abundant source of biomass that could be hydrolyzed to yield fermentation sugar for the production of fuel ethanol. In this study, hydrolysis of WDG using mixed acid as catalysts was examined with the indices of the concentration of reducing sugar and furfural. The structural characteristics of WDG before and after acid treatment were also discussed by means of SEM, FTIR and XRD. The results indicate that there are 59.32gL-1 reducing sugar under the conditions of 100°C, solid-liquid ratio of 1:12 gmL-1, acid concentrations of 2.0% and time of 120 min, with the conversions rate of 77.38% and 62.50% for hemicelluloses and cellulose, respectively. SEM photographs show that the structural modifications after acid treatment are pronounced in comparison to that of WDG, which present a rigid and compact morphology. A lot of large irregular pores with different sizes and shapes are formed and the structures are also severely distorted resulting in the increasing surface exposure and porosity. Instrumental analyses with FTIR and XRD indicate that the strength of characteristic peaks for corresponding typical functional groups of each component are changed compared with the feedstock, and there is an increase of the crystallinity index when WDG is subjected to the MACH treatment.