Comparative kinetic studies of delignification of sugarcane bagasse using Hydrogen Peroxide and Sodium Hydroxide

Abstract

Delignification kinetics of sugarcane bagasse by hydrogen peroxide and sodium hydroxide were studied and results compared. A reactor equipped with pH and temperature controls was used to study effects of de-lignifying agent concentration (3 and 6%), bagasse particle diameter (0.3, 0.6 and 1.2 mm), temperature (30, 40, and 50 ^oC) and pH (8, 9, 10 and 11) on de-lignification of sugarcane bagasse over 48 h period. A pseudo-first order kinetics of 64.4 kJ/mol and 44.04 kJ/mol activation energies were found to represent delignification kinetics using hydrogen peroxide and sodium hydroxide respectively. Statistical analysis of the experimental and predicted results using MathCard software to simulate model equation for degree of delignification indicated positive correlations (0.874-0.993) for both hydrogen peroxide and sodium hydroxide. Results showed increase degree of delignification with temperature and pH values. Treatments using 0.3 mm diameter showed increase de-lignification compared with those for 0.6 and 1.2 mm diameters indicating pore diffusion limitation at larger particle sizes. Maximum degree of de-lignification of 62.2% was obtained at 50 ^oC and pH 11 using 0.3 mm particle diameter after 48 h treatment with 6% sodium hydroxide. Hence, the derived model predicts degree of delignification of bagasse using these agents with high accuracy.

Key words: Sugarcane bagasse, De-lignification, Sodium hydroxide, Reaction model