Photodegradation of salicylic acid in aqueous phase by TiO2 / UV System

Résumé

Man uses the background where he lives and transforms it; he becomes the factor controlling the ecosystem conditions and the main reason of degradation of environment especially by industrialization and rejecting wastewaters. Water pollution can be soluble or not. The main categories of the water soluble pollution are represented by: inorganic pollutants, biological pollutants and organic pollutants. There are numerous methods to treat wastewaters; they depend on the characteristics of pollution. This study aims to examine the application of the advanced oxidation process, particularly heterogeneous photocatalysis. This process has been applied for degradation of salicylic acid dissolved in water; its degradation occurs in a photocatalytic reactor made up of a titanium dioxide (TiO2) as a semiconductor supported on a glass plate placed at the middle of the reactor and subjected to the U.V irradiation. The assessment of the parameters influence related to the reactor such as recirculation flow and initial concentration of pollutant has shown that at low recirculation flow, the photodegradation of pollutant was accelerated about 98 % of salicylic acid was degraded after 3 hours of irradiation, in addition the heterogeneous photocatalysis process is applied even at low concentration. Kinetic analyses indicated that the photodegradation of pollutant can be described by a pseudo-first-order reaction. The Langmuir Hinshelwood model was used to assess the kinetics of the heterogeneous photocatalytic process, the rate constant, kapp for the photocatalytic degradation was determined at different concentrations.