Hydrogen peroxide bleaching of Arundo donax L. kraft-anthraquinone pulp-Effect of a chelating stage

Total chlorine free (TCF) and elemental chlorine free (ECF) bleaching sequences were applied to an Arundo donax L. (giant reed) unbleached kraft-anthraquinone pulp, using different sequences with hydrogen peroxide and chlorine dioxide stages. The evolution of ISO brightness, kappa number and pulp viscosity was observed for each stage in all bleaching sequences, as well as the process selectivity. The best results were obtained with the XOQDP sequence with a final ISO brightness of 80%. The effect of a chelating stage before the hydrogen peroxide stage was studied, and the results showed higher pulp viscosity, less peroxide consumption and higher pulp brightness, when this treatment is applied.