TITANIUM DIOXIDE-PHOTOCATALIZED OXIDATION OF 2,4-DICHLOROPHENOL

Titanium dioxide has been used as photocatalyst for the degradation of 2,4-dichlorophenol. This process takes place under UV-illumination obtaining high yields for diluted aqueous solutions. The yield of 2,4-dichlorophenol oxidation depends on the irradiation time, the incident light intensity, the mass of semiconductor in suspension, the initial concentration and very slightly on the pH and temperature. The initial rate values of 24-dichlorophenol oxidation follows Langmuir-Hinshelwood kinetics, with a rate constant and an equilibrium adsorption constant of 4.5 x 10(-5) M/min and 3.2 x (103)/M, respectively, at 25 degrees C. From this data it is assumed that the oxidation of 2,4-dichlorophenol occurs through reaction with OH radicals originated from valence band processes in the surface-hydroxylated TiO2 particles under illumination.