EFFECTS OF DIFFERENT ACTIVATION PROCESSES ON H2O2/TAED BLEACHING OF Populus nigra CHEMI-THERMO MECHANICAL PULP

Tetra acetyl ethylene diamine (TAED) was used as an activator in H2O2 bleaching to improve bleaching efficiency. The present work was aimed at confirming different activations for various H2O2/TAED bleaching processes, including the addition of acetic anhydride and the stepaddition of sodium hydroxide. The results showed that an acetic anhydride dosage of 1%, an acetic anhydride treatment time of 10 min, and an addition time of 45 min were the optimal treatment conditions. The optimum processes of NaOH step-addition treatment in H2O2 bleaching and in H2O2/TAED bleaching also were confirmed, respectively. The o-quinone contents of H2O2 bleached lignin and H2O2/TAED bleached lignin were determined. The results indicated that H2O2/TAED bleached lignin has a lower o-quinone content than H2O2 bleached lignin, which is one of the reasons for the H2O2/TAED bleaching process having better bleaching efficiency than H2O2 bleaching.