Degradation photocatalytique du 1-naphtol en presence d’oxyde de fer naturel chromophore et de tio2 en solution aqueuse

Abstract

This work was carried out in the field of water treatment using advanced oxidation processes (AOPs), particularly the photocatalysis process in heterogeneous environments. The 1-Naphthol (1-NP) was chosen as a model contaminant molecule to evaluate the photocatalytic performance of a naturel mineral (NM). In a homogeneous medium, the degradation of 1-NP has been studied by different photochemical processes (UV254 nm, UV365 nm, solar irradiation and H2O2/UV254 nm) and by the Fenton's reagent (Fe2+/H2O2). The performance comparison of the different processes studied shows that the process of Fe2+/H2O2 is the most effective. The 1-NP was degraded by heterogeneous photocatalysis using TiO2 and Fe2O3 as supporting chromophores. This study showed the relative efficiency of the NM in inducing the 1-NP photodegradation. The photodegradation kinetics are more important when using TiO2. In the presence of NM, it appears that the •OH radicals are not involved in the degradation mechanism of 1-NP. Moreover, the study of the system 1-NP - NM - H2O2 showed that 1-NP disappears more rapidly due to the intervention of the hydroxyl radicals generated by the Fenton and photoFenton reactions. The degradation rate depends on the concentration of hydrogen peroxide and the pH of the medium. It has also been observed that the addition of the oxalic acid in a NM solution significantly enhances the rate of the degradation of the substrate similar to that of hydrogen peroxide. This degradation is carried out by the oxidizing action of the hydroxyl radicals. However, the alkalinization of the medium completely restrains the reaction. Different natural irradiation tests have shown a more rapid degradation of the pollutant. This environmentally friendly method appears to be very effective in the treatment of wastewater.