Kinetic and thermodynamic analysis of dilute acid hydrolysis of sugarcane bagasse

Abstract

This study has investigated kinetic and thermodynamic features of dilute acid (2% v/v H2SO4, 1:30 w/v) hydrolysis of sugarcane bagasse. Time profiles of xylose formation in range of 100°–130 °C and treatment period of 0–120 min have been analysed with modified biphasic Saeman model. Generation of glucose, arabinose and inhibitory products (furfural, 5-HMF and acetic acid) have also been analysed. Easy-to-hydrolyse fraction of hemicellulose increased with temperature. Activation energies for hydrolysis and xylose degradation were 60.3 and 83.4 kJ/mol, respectively. Although maximum xylose yield (0.81 g/g hemicellulose) was obtained at 130 °C, significant fraction of xylose was converted to inhibitory products. Thermodynamic analysis revealed ΔH = 57.06 kJ/mol and ΔS = −1.05 kJ/mol for hydrolysis. Moreover, xylose formation is thermodynamically more favoured (ΔG = 468.53 kJ/mol) than degradation (ΔG = 482.17 kJ/mol). Optimum conditions for hydrolysis are: temperature = 120 °C, time = 30 min, xylose yield = 0.76 g/g hemicellulose.