OXYGEN DELIGNIFICATION OF SODA AND SODA-AQ BAGASSE PULPS

Addition of a small fraction (0.1% on ovendry raw-material basis) of a nthraquinone (AQ) during soda pulping of bagasse reduced pulp kappa nu mber by almost 40% (from kappa no. 21.5 for soda pulp to kappa no. 13. 3 for soda-AQ pulp) at constant H-factor. Extended delignification of soda and soda-AQ pulps with oxygen further reduced the kappa numbers b y almost 50% (to 11.8 and 6.8, respectively). Yield loss during oxygen delignification was marginal for both soda and soda-AQ pulps. Oxygen- delignified pulps suffered slight losses in viscosity and fiber streng th, but brightness increased significantly. The lower kappa numbers of oxygen-delignified pulps will significantly reduce chemical demand du ring bleaching, which is both economically and environmentally sound.