The Effect of Using Anthraquinone on Hornbeam Neutral Sulfite Pulp Properties

This research was performed with the aim of using anthraquinone (AQ) as catalyst in order to improve the properties of the pulp from Hornbeam, neutral sulfite semi chemical (NSSC) pulping. The pulping was carried out at three screen yield levels of 55, 60 and 65%. The cooking conditions were chosen as: temperature (175˚C), time (Variable), total chemicals 14% and anthraquinone 0.1% to achieve the screen yields. In all cooking trials, sodium sulfite to sodium bicarbonate weight ratio was constant equal to 4.5:1. The cooking liquor to wood ratio was 4 to1 respectively. The results indicated that anthraquinone decreased the cooking time (5 to 10 min.), pulp reject (1.8 to 0.3%), and kappa number (3 to 4 units) due to its selectivity. Also, all strength indices (including burst, tear, and tensile), RCT and CMT of the hand sheets were increased significantly (p≤ 0.05) by using anthraquinone. Regarding optical properties, the brightness of hand sheets with screen yield of 65, 60, and 55% were increased significantly 76.5, 47.5, and 16.4%, respectively by adding AQ in the cooking stage. Paper opacity dropped slightly, but the change was not significant.