HEMICELLULOSES EXTRACTION FROM GIANT BAMBOO PRIOR TO KRAFT AND SODA AQ PULPING TO PRODUCE PAPER PULPS, VALUE-ADDED BIOPOLYMERS AND BIOETHANOL

Hemicelluloses were pre-extracted from giant bamboo with dilute H2SO4 prior to Kraft and soda AQ pulping. The reaction conditions were selected to convert most of the hemicelluloses into soluble monomeric sugars, leaving almost unaltered the cellulose and lignin from the residual solid phase. A Central Composite Design was used to study four pre-extraction variables: H2SO4 concentration (0.1-0.5 % v/v), solid/acid solution ratio (1/3.5-1/5.5 g/mL), temperature (80-140 °C) and time (10-50 min). Temperature had a dominant influence on the hydrolysis process. A maximum xylose yield – of 83.4 % – (based on oven dry raw material mass) was obtained at a 0.4 % v/v H2SO4 concentration, a solid/solution ratio of 1/4 (g/mL), at 140 °C and an extraction time of 40 min. The bamboo, from which 2.4 % hemicellulose had been extracted, was subsequently pulped by both Kraft and soda AQ pulping methods. Soda AQ pulping gave the best results in terms of pulp yield, viscosity and kappa number, compared to the non-extracted bamboo, pulped under similar conditions.