EFFECT OF LIGNIN CONTENT ON OZONE BLEACHING AT MEDIUM CONSISTENCY

The effect of pulp lignin content an ozone bleaching at medium consist ency was studied in the laboratory. A constant charge of ozone was app lied to unbleached chemical pulps with varying lignin contents (kappa no. 10-50). The degree of delignification from ozone bleaching was mea sured as the drop in kappa number. Cellulose degradation from ozone bl eaching was measured as the decrease in pulp viscosity. The results sh ow a correlation between pulp lignin content and the efficiency of ozo ne bleaching. The best selectivity of ozone bleaching occurs at limite d reduction of lignin content thus highlighting the need for extended delignification prior to bleaching. The data presented in this report are potentially useful for developing an ozone-bleaching module for co mputerized simulation and optimization of ozone bleaching.