Effect of temperature on kraft black liquor degradation by ZnO-photoassisted catalysis

The ZnO-photocatalysed reaction of kraft black liquor, obtained from P. radiata pulping, was studied to determine the kinetic parameters that govern CO2 evolution. The mineralization reaction exhibits a first-order dependence on the dissolved oxygen concentration and a half-order dependence on the concentration of the substrate at 25 degrees C. The catalysed reaction accounts for more than 95% of the CO2 production, at all temperatures studied, and the uncatalysed reaction accounts for 5 %. The apparent activation energy of the catalysed process was estimated to be 43.1 kJ mol(-1).