Solar photocatalysis treatment of phytosanitary refuses: Efficiency of industrial photocatalysts

In the field of advanced oxidization processes based on solar radiation, heterogeneous solar catalysis involves exciting a photocatalyst with UV rays and one of the major problem encountered is optimizing the use of the sunlight. Catalysts in suspension develop the best ability to degrade polluting molecules. In this study, two TiO2 catalysts in suspension which develop the best ability to degrade polluting molecules, with a granulometric ratio of 1000, have been investigated. All the experiments were performed under natural sunlight in a photoreactor consisting of three identical but independent reactors. A simple kinetic model of degradation is purposed for the media each in its optimal configuration, considering the irradiation, the catalyst and pollutant concentrations. First of all, we show that the kinetics of degradation decline as a function of the quantity of photons used and that the two catalysts (with a granulometric ratio of 1000), achieved similar performances when they were used in their optimal configurations. Secondly, the logarithm of the concentration of pyrimethanil decreased linearly as a function of the combination Q(UV)C(TiO2)(m). This indicates the direct dependence of the quantity degraded on the quantity of UV energy effectively available for the photocatalytic reaction. (C) 2011 Elsevier B.V. All rights reserved.