Kinetics of Hydrogen Peroxide Brightening of Western Red Cedar (Thuja plicata Donn) CTMP

Abstract

The use of western red cedar mechanical pulp is limited by its very low brightness. This article presents the kinetic expressions for hydrogen peroxide brightening of western red cedar chemimechanical pulp. The significance of the results for the reaction mechanism and for brightening under practical conditions is discussed. The kinetics of peroxide brightening of western red cedar chemimechanical pulp was monitored at the three absorption maxima—357 nm, 457 nm, and 550 nm—in the UV-visible spectra. The reaction order with respect to hydrogen peroxide was around 1 at all three wavelengths. The reaction order with respect to chromophores was approximately 2.4 at the higher wavelengths and 5 at 357 nm. The kinetic equations were successful in predicting brightness values obtained under practical conditions.

Keywords:

• Brightening
• chromophores
• hydrogen peroxide
• kinetics
• mechanism
• reaction order
• UV-visible
• western red cedar

We are indebted to Dr. D. Fortier (Catalyst Paper) and Dr. J. Turnbull (Jim Turnbull and Associates) for advice and supply of western red cedar, and to PAPRICAN Vancouver Laboratory for use of their facilities. This research was supported by The Science Council of BritishColumbia and theNatural Sciences andEngineeringResearchCouncil of Canada.

Notes

¹Trial 4 conditions; Table 1.

∗ This work.