Kinetics of sulfur dioxide-alcohol-water (SAW) pulping of sugarcane straw (SCS)

摘要

Pulping kinetics of sugarcane straw (SCS) using the sulfur dioxide (SO2)-alcohol-water (SAW) system were investigated with different solvents (methanol, ethanol, and isopropanol) in order to evaluate the effect of the solvents. The methanol, ethanol, and isopropanol SAW pulps are identified as SMW, SEW, and SPW, respectively. The pulping experiments were carried out at 135 degrees C, 145 degrees C, and 155 degrees C with cooking liquor (L/F = 4 L/kg feedstock) composition; SO2/alcohol/water of 12/44/44 w%. The pulps were characterized in terms of yield, kappa number, viscosity, cellulose, and hemicellulose and lignin content. After a fast initial dissolution phase, two regimes of delignification were identified in all solvent systems: a bulk and a residual phase. Bulk delignification and xylan removal followed first order kinetics in residual lignin and xylan, respectively, while the cellulose hydrolysis rate was zeroth order in cellulose.