REMOVAL OF ORGANIC CONTAMINANTS IN PAPER PULP TREATMENT EFFLUENTS BY TIO2 PHOTOCATALYZED OXIDATION

TiO2 slurries under UV light irradiation were used for the oxidation a nd removal of the organic load of effluent from the bleaching of paper pulp. TOC was the main analytical parameter used to characterize the reaction progress, although GOD, AOX and color also received periodic attention. Conditions such as the catalyst load, light intensity, pH, temperature, and concentration of O-2 and organic matter were changed through several series of experiments in order to determine their effe ct. A zero order kinetics accounts for the observed variation of TOC w ith time during most of the reaction, the rate constant being 0.25-0.4 0 ppm min(-1) at 25 degrees C. This behavior is explained in terms of a Langmuir-Hinshelwood rate equation in a highly substrate concentrate d system. (C) 1997 Elsevier Science S.A.