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]0.11X0.92. 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. © 2018, BioResources.