Photocatalytic removal of tartrazine dye from aqueous samples on LaFeO3/ZnO Photocatalysts

Dyes represent a very important group of water pollutants that appear in the effluents of different industries. These contaminants, by preventing the penetration of light, can have negative effects on the aquatic environment, causing problems to the ecosystem, and possibly being carcinogenic and genotoxic on human health. In particular tartrazine is a commonly not-biodegradable dye used in food industries and it, in high amount, could cause allergic and/or intolerance reactions. In the past decade only few effective photocatalysts for organic dye degradation under visible-light irradiation has been reported. Effective photocatalysts, such as ZnO, however, exhibit photodegradation activity only under ultraviolet irradiation. The coupling of ZnO, having a band gap of 3.2 eV, with low band gap photocatalysts could induce the removal of the dyes under visible light. So, in this work, LaFeO3, which has a band gap of about 2.1 eV, was supported on ZnO surface. The aim of this work was to evaluate the efficiency of LaFeO3/ZnO on the degradation of tartrazine under UV but also under visible light. Furthermore it was evaluated the optimal composition in terms of LaFeO3 amount on ZnO.