Oxygen-peroxide (Eop) delignification and peroxide (P) bleaching of bagasse kraft pulp

An EopQP sequence is used to delignify and bleach a bagasse kraft, pulp. In the Eop step,,a reduction of the kappa number by 60 per cent and improvement in the brightness,by 16.5 units were achieved. The Q step reduces the content of Mn, Fe and Cu ions by 48-60 per cent. A bleaching system consisting of 4 per cent H2O2, 2.5 per cent NaOH, 0.3 per cent MgSO4, and 0.05 per cent DTPMPA could bleach the EopQ treated pulp to 80 per cent ISO brightness, 2.6 kappa number and - 700 mL/g viscosity. The brightness is increased to 82 per cent at reasonable viscosity values (> 650 mL/g) by adding 0.05 per cent 1,10-phenanthroline to a bleaching system containing lower peroxide concentration (3 per cent) and higher DTPMPA charge (0.1 percent).