Oxidative Pretreathent with Hydrogen Peroxide Prior to Alkaline Pulping

Oxidative pretreatment of Southern pine wood with alkaline hydrogen peroxide increased its rate of delignification during subsequent kraft and soda-AQ pulping. Effective pretreatment required the removal of transition metals prior to oxidation at high pH (12), low teaperature (50°C) and short reaction time (<45 min.). Compared with reference pulping, pretreatment with 1.4% H2O2 and 3.3% NaOH on wood reduced pulping time to 35 kappa number by 30 minutes (at 170°C). Pre-oxidation resulted in pulp with yield-kappa number and viscosity-kappa number relations equal to or greater than those of corresponding reference pulp. For both kraft and soda-AQ pulp, bleachability, in terms of chemical charge and final viscosity, was unaffected by pre-oxidation while total bleached yield was increased by about 2% on wood. Handsheet strengths for unbleached and bleached kraft pulp were unaffected by oxidative pretreatment whereas those for unbleached soda-AQ pulp were improved to kraft-like levels. However bleached soda-AQ pulp strengths, both with and without pre-oxidation, were less than those of corresponding bleached kraft pulp.