ELIMINATION OF DIRECT AZO DYE RED 80 IN AQUEOUS SOLUTION BY HETEROGENEOUS PHOTOCATALYSIS

The photoelimination, at ambient temperature, of aqueous solutions of Direct Red 80 dye (DR 80) in the presence of TiO₂ and ZnO catalystshas been studied in the presence of UV radiation generated by an artificial light source.We have determined the influence of several physico-chemical parameters (the mass of the catalyst, the initial concentration of dye and the initial pH of the solution) which govern the kinetics of degradation of this pollutant in order to be in optimum conditions.The catalysts used show a good photocatalytic activity. Indeed, for the first 15 minutes of irradiation, approximately 96% and 87% of the dye is eliminated in the presence respectively of TiO₂ and ZnO. The kinetics of photocatalytic degradation were investigated and modeled by the Langmuir-Hinshelwood equation, by which the k rate constant and the K_LH adsorption equilibrium constant were evaluated.The results showed that the pH significantly affects the process of the elimination of the dye. The maximum rate of degradation of DR 80 is observed at pH = 3