Extraction of lignin from sugar cane bagasse and Pinus taeda wood chips using ethanol-water mixtures and carbon dioxide at high pressures

The obtained results indicate important differences from the organosolv process, which may be due to the presence of carbon dioxide and/or the high pressure employed in this work. The pulp yields and extent of delignification showed, as expected, a much greater influence of temperature than of pressure. The best results were obtained at 16.0 MPa and 190 °C. Under these conditions the pulping yield and the residual Klason lignin content from P. taeda wood chips were 43.7 and 4.9%, respectively, and from sugar cane bagasse 32.7 and 8.7%, respectively. These data correspond to a delignification extent in the order of 93.1% for P. taeda wood chips and 88.4% for sugar cane bagasse. Higher pressures lead to similar pulp yields but higher residual lignin contents.