Photocatalytic degradation of Indigo Carmine using aluminum-doped titanium dioxide/zinc ferrite nanocomposite under visible light

In this study, a novel visible light-active photocatalyst named aluminum-doped titanium dioxide/zinc ferrite (Al-TiO2/ZnFe2O4) nanocomposite was successfully synthesized by sol-gel and mechano-chemical routes. The structural properties of the fabricated photocatalyst were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance UV-vis spectroscopy, and Fourier transform infrared spectroscopy. The capability of the prepared photocatalyst was evaluated for the photodegradation of Indigo Carmine dye. It was observed that the Al-TiO2/ZnFe2O4 nanocomposite containing 0.5%wt Al and 5.0%wt ZnFe2O4 could completely degrade Indigo Carmine under visible light irradiation. Numerous factors affecting the photocatalytic process efficiency, such as pH, amount of the nano-photocatalyst, and concentration of the dye, were investigated and optimized. Total organic carbon measurement was carried out to determine the rate of Indigo Carmine dye mineralization in the photodegradation process. The nanocomposite showed good stability for three replication of the photocatalytic reaction. The kinetics of the reaction was studied, and based on the obtained results, the photocatalytic degradation of Indigo Carmine follows pseudo-first-order degradation kinetics. Trapping experiments using various scavengers indicated that the holes (h +) and superoxide radical (O-center dot(2)-) were the main reactive species in the photodegradation process of Indigo Carmine dye.