Generalized Curves of Delignification and Cellulose Degradation During Ozone Bleaching, 2001 Pulping Conference Proceedings

J. King, A. R. P. van Heiningen--It has been shown [1] that the progress of delignification and cellulose degradation during ozone bleaching can be described by movement of a lignin (and cellulose) degradation front through the fiber wall from the external fiber surface to the lumen. The rate of delignification is determined by diffusion of ozone through the reacted fiber wall region. The cellulose degradation occurs mostly by radical species generated by fast lignin-ozone reactions inside the front. Based on this so-called loshrinking coreli model, a quantitative description of the effects of ozone partial pressure, temperature, pulp consistency and kappa number on the ozonation kinetics were reported [2,3] for Hemlock kraft pulp. The effect of pulp type could also be described by this model [4] by considering the average fiber wall thickness of the wood species. The objective of the present study is to provide predictive equations for the delignification and cellulose degradation rates of pulps, based solely on the physical and chemical fiber characteristics, and the process conditions.