Description of kraft cooking and oxygen–alkali delignification of bamboo by pulp and dissolving material analysis

The oxygen delignification of two bamboo (Bambusa procera) kraft pulps with kappa numbers of 13.6 and 20.0 were studied under typical conditions. Based on detailed analysis data on both the kraft and oxygen-delignified pulps and the corresponding spent liquors (black liquors and oxygen stage effluents), three yield and four selectivity estimation methods, utilizing component material balances, were tested resulting in the value ranges 96.2–97.9% and 43.5–60.4%, respectively, for oxygen delignification process studied. The traditional selectivity using the viscosity and kappa number relation was 66.9–68.4%. The studied bamboo kraft pulps behaved typically as birch kraft pulps during oxygen delignification, resulting, for example, in similar carbohydrate-derived degradation products.