Chiang Mai Journal of Science

This work was to study the catalytic oxygen delignification (Ocat-stage) prior to elemental chlorinefree (ECF) bleaching. For this purpose, 0.10% (o.d.p) of ZnPSC6-GO was used in Ocat-stage (OZnGO). It was shown that Ocat-stage improved the bleached pulp properties and decreased wastewater load in comparison to ODED sequence. Consequently, OZnGODED showed to be the best sequence for the bleaching of bamboo kraft pulp. The viscosity, brightness, tensile index, tear index and burst index of the final bleached pulp were found to be 876 mL g-1, 90.7 % ISO, 58.4 Nm/g, 13.63 mN•m2/g and 5.41 kN•m2/g, respectively. These values were high in comparison to ODED sequence. A potential reduction of 70.86%, 65.49%, 73.71%, and 68.29% in AOX, color, COD and BOD, respectively was observed on applying the OZnGO stage compared to ODED sequence, while the formation of chlorinated compounds in effluent was dramatically reduced. Finally, the mechanism was presented according to the observations on relative content of lignin and hexenuronic acid (HexA) of bleached pulp.