Dissolving pulps by oxidation of the cellulosic fraction of lignocellulosic waste

Abstract

Cellulosic fractions of Eucalyptus sp. sawdust pulp and of sugarcane bagasse pulp, which had been subjected to hydrothermal and alkaline treatments, were purified by oxidative means (oxygen and ozone, followed by an alkaline extraction) to obtain dissolving pulp. The properties of the obtained pulps were evaluated and compared with those of commercial dissolving pulps. Eucalyptus sawdust pulp achieved 70% delignification after oxygen treatment and a kappa number of 5.8. Sugarcane bagasse pulps achieved 83% delignification and a kappa number of 8.7. Intrinsic viscosities within the range of specifications for dissolving grade pulps were obtained in the experiments on eucalyptus sawdust pulp. Higher values than required were obtained for sugarcane bagasse pulp. Retention values in 18% alkali were within the range of specifications for dissolving grade pulps, the highest values being obtained for alkaline extraction in the absence of hydrogen peroxide. Hydrogen peroxide addition in alkaline extraction produced high solubility values in both kinds of pulps.