Photodegradation of Tartrazine dye favored by natural sunlight on pure and (Ce, Ag) co-doped ZnO catalysts

In this work, the synthesis of pure and (Ce, Ag) co-doped ZnO has been successfully accomplished by a solvothermal process. The synthesized samples were characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic ability of the samples is estimated through degradation of tartrazine in aqueous solution under photocatalytic conditions. The degradation study carried out for a reaction period of 90 minutes at and a free pH = 6.0, found that the dye degradation is 44.82% for pure ZnO and 98.91% for (Ce, Ag) co-doped ZnO samples indicating its excellent photocatalytic ability. Tartrazine mineralization was also studied by calculating the degradation of Chemical Oxygen Demand (COD). The effect of operating parameters such as catalyst dose, initial concentration of tartrazine, initial reaction pH and nature of light source has been optimized for tartrazine degradation as a function of time. The reusability of ZnO and (Ce, Ag) co-doped ZnO catalysts has also been studied and its photocatalytic efficiency was found to be unchanged even after 6 cycles of use. The mechanism of photocatalytic activity has also been proposed.