Kinetics of Oxidation of a Hemicellulose Model Compound by Chlorine Dioxide in Bleaching

Kinetics of the oxidation of D-xylose, a hemicellulose model compound, by chlorine dioxide was studied under simulated bleaching conditions. The final reaction product, chloroacetic acid, which is a type of adsorbable organic halogen (AOX), was detected by gas chromatography-mass spectrometer (GC-MS). The kinetic equation was expressed as dW/dt = 2.36e(-560/T)[H+](0.05)[ClO2]X-0.11(0.92). The reaction exhibited first-order kinetics, with a good agreement between the experimental and modelling data. The reaction activation energy was 4.66 kJ.mol(-1). Thus, the process is not controlled by a chemical reaction, but rather, it is controlled by hemicellulose properties. These results might have potential for resolving the major problems of environmental pollution in elemental chlorine-free (ECF) bleaching of pulp.