Kinetic and thermodynamic study of corncob hydrolysis in phosphoric acid with a low yield of bacterial inhibitors

Abstract

In this research, the kinetics and thermodynamics of corncob hydrolysis in dilute phosphoric acid, obtained at different acid concentrations, temperatures, and reaction times are reported for the first time. The sugars were obtained mainly from hemicellulose and cellulose degradation: trehalose, arabinose, glucose, and fructose were produced under minimal hydrolysis conditions and xylose under the most severe hydrolysis conditions. The highest sugar yield was 54 g of sugar per 100 g of corncob under most severe conditions with a degradation factor of only 0.03 to furfurals. The hydrolysates can be used without any treatment for biogas production by dark fermentation. Kinetic constants calculated from the Saeman and first-order models allowed us to determine the thermodynamic parameters and understand the energetic changes during hydrolysis. The activation energy for sugar production was 52 kJ mol−1, and the activation energies were 78 kJ mol−1 and 115 kJ mol−1 for sugar decomposition into furfural and 5-HMF, respectively.