Kinetics of SO2-ethanol-water (AVAP®) fractionation of sugarcane straw.

Kinetics of SO2-ethanol-water (AVAP®) fractionation was determined for sugarcane (SC) straw in terms of pulp composition (non-carbohydrate components, cellulose, hemicelluloses) and properties (kappa number, pulp intrinsic viscosity in CED and cellulose degree of polymerization). Effect of temperature (135-165°C) and time (18-118min) was studied at fixed liquor composition (SO2/ethanol/water=12:22.5:65.5, w/w) and a liquor-to-solid ratio (4Lkg(-1)). Interpretation is given in terms of major fractionation reactions, removal of non-carbohydrate components and xylan, as well as acid hydrolysis of cellulose, and is compared to other lignocellulosic substrates (beech, spruce and wheat straw). Overall, SO2-ethanol-water process efficiently fractionates SC straw by separating cellulose from both non-carbohydrate components and xylan while reducing cellulose DP.