Oxidative Pretreatment of Loblolly Pine with Alkaline Hydrogen Peroxide and Soda-AQ Pulping, 1990 Pulping Conference Proceedings

Oxidative pretreatment of loblolly pine (Pinus taeda L..) with alkaline hydrogen peroxide improved the selectivity of soda-AQ (SAQ) pulping. To achieve an effective pre-oxidation, removal of transition metals from the chips is essential. A parametric investigation was undertaken to optimize the conditions for the removal of transition metals from the chips by a low temperature acid DTPA prehydrolysis procedure. In comparison to a standard SAQ cook, the SAQ pulping of pre-oxidized chips required 14% less chemicals (A EA = -2.2% as Na2O at 1500 H-factor) and 28% less energy (A H-factor = -420 at 16% EA as Na2O) to obtain a pulp of Kappa number 60. The TAPPI viscosity of Kappa number 60 pulp from pre-oxidized chips was about 2.2 mPa.s higher than the standard SAQ pulp of similar Kappa number. A three-stage sequential pre-oxidation was carried out to evaluate the pulp quality and cost-effectiveness of the process. Under identical pulping conditions, chips from sequential pre-oxidation resulted in a low Kappa number (A Kappa number = -6.0) and high viscosity (A = +2.O mPa.s) pulp (Standard pulp: Kappa number = 81.2 and TAPPI viscosity = 26.9). The unbleached SAQ pulps from pre-oxidized chips are 20% stronger than the standard pulp of same Kappa number.