KINETICS OF POLYSACCHARIDE HYDROLYSIS IN THE ACID-CATALYZED DELIGNIFICATION OF EUCALYPTUS-GLOBULUS WOOD BY ACETIC-ACID

The influence of operating conditions (temperature, HCl catalyst concentration and time) on the percentage of xylose solubilized in the acid-catalysed delignification of Eucalyptus globulus wood by acetic acid was studied using an incomplete 3 x 3 x 3 factorial design. Regression analysis afforded an equation satisfactorily correlating the experimental results. A kinetic model of polysaccharide hydrolysis is proposed which involves two parallel first order reactions: one the fast hydrolysis of hemicellulose and the other the slower hydrolysis of cellulose. Under mild operating conditions (i.e. at low temperatures and HCl concentrations) only the fast reaction occurs, leaving the cellulosic fraction as the unhydrolysed residue.