EUCALYPTUS ACETOSOLV PULPING - OPTIMIZATION OF THE COOKING CONDITIONS AND CHARACTERIZATION OF THE PULP AND LIGNIN

Acetosoly pulping of Eucalyptus grandis wood has been studied, for evaluating its potential for industrial use. Pulping of eucalyptus wood chips was performed in 93% acetic acid under reflux and normal pressure, using an inorganic acid as catalyst. The parameters investigated were solved to wood ratio, cooking time, chips size, nature and amount of the catalyst. Pulping of 4-6 mm thick chips with a solvent/wood ratio of 7/1 for 3 h (standard conditions) and with 32 mmol/L of HCl as catalyst gave a pulp with 63% yield and a kappa number 24. Cooking time and the solvent/wood ratio have small infuence on the kappa number, but continuous extraction after cooking gave a pulp with a kappa number 18. The use of HBr as catalyst has advantage in comparison to HCl. Pulping under standard conditions rising 97 mmol/L of HCl gave a pulp with 56% yield, a kappa number 15 and a viscosity of 15 cP. Better results were obtained (60% pulp yield, kappa number 15 and viscosity of 18 cP) with only 19 mmol/L of HBr. HClO 4 has a smaller effect and FeCl 3 , LiCl and ZnCl 2 have no catalytic effect in this pulping system. The experimental Klason lignin/kappa number ratio was 0.36. The pulps were also characterized by X-ray diffraction and FTIR spectroscopy. The lignin precipitated from the liquors was characterized by its Klason lignin content, molecular weight distribution, FTIR and 13 C-NMR spectra.