ORGANOSOLV PULPING .5. FORMIC-ACID DELIGNIFICATION OF EUCALYPTUS-GLOBULUS AND EUCALYPTUS-GRANDIS

Organosolv pulping mediated by formic acid was evaluated. Wood of Eucalyptus globulus and Eucalyptus grandis was cooked with formic acid under different conditions of solvent ratio (formic acid:water), catalyst concentration, temperature and time of treatment. For E. globulus, the best results for sawdust samples were obtained at 90-degrees-C after 90 min of cooking, with a solvent ratio of 80:20 (vv-1), a charge (wood:solvent ratio) of 1:30 and 0.44% (wv-1) of catalyst. In the case of E. globulus chips, the concentration of catalyst used was 0.22%, the charge was 1:10, and soaking and preheating were used. For a sample of E. globulus soaked in water for 72 h, the pulp yield was 56%, Kappa number 22 and reject content 1.6%. E. grandis wood needed more drastic conditions. Cooking of E. grandis chips with formic acid (99%) at 95-degrees-C, 0.22% catalyst, charge 1:10, resulted in a pulp yield of 43%. The Kappa number was 31, reject content 0.1% and the cellulose and Klason lignin contents were 88% and 8%, respectively.