Can mixed oxides act as efficient photocatalysts for the elimination of organic water pollutants?

New mixed-metal oxides containing zinc and lanthanum were prepared by coprecipitation. The synthesized nanocomposites were calcined, and characterized by scanning electron microscopy (SEM), X-ray diffraction, FT-IR, BET and DR analysis. The calcined sample showed a higher crystalinity, confirmed by sharper and more intensive diffraction lines. On the other hand, a slight decrease of the band gap was found for the calcinated material. The photocatalytic effectiveness of the synthesized nanocomposite to degrade a refractory water micropollutant, named clofibric acid (CA) was investigated in this work under ultraviolet (UV-A) irradiation. Elimination and mineralization of the target molecule were evaluated by HPLC and TOC measurements. The influence of CA initial concentrations (3-50 ppm), irradiation time (60-240 min), catalyst loading (20-500 mg/L), water matrix and radiation intensity were evaluated in detail. The CA was completely eliminated just after 110 min. of reaction (10 mg/L CA concentration and 500 mg/L catalyst). Moreover, TOC measurements showed a good mineralization (70 %) under these conditions. Process efficiency was found to decrease with increasing the initial concentration (10-50 mg/L). Obtained results demonstrated the merit of the synthesized materials to be considered as promising photocatalyst for the wastewaters treatment.