Photodegradation of Amido Black 10b Dye Under Visible Light Using Ni and Zn Ferrite Catalysts Prepared by a Simple Modified Sol–Gel Method

The pure α -Fe 2 O 3 , NiFe 2 O 4 , and ZnFe 2 O 4 were prepared by a simple modified sol–gel method. The prepared catalysts were characterized by X-ray diffraction, transmission electron microscope, surface area, Zeta potential and optical techniques. The ferrite structure of samples is confirmed. The photocatalytic activity was evaluated toward Amido black 10b dye degradation under visible light at different pHs of 4, 8, and 10 for 90 min irradiation time. The photodegradation toward Amido black b10 dye reached maximum value at pH 8, and it reaches 92%, 89%, and 85% over ZnFe 2 O 4 , Fe 2 O 3 , and NiFe 2 O 4 photocatalysts; respectively. The increased photoactivity of the ZnFe 2 O 4 sample can also be attributed to its lower bandgap of 2 eV, the formation of the − OH-surface group. Since –OH can interact with the photoexcited holes that were originally formed on the catalyst surface, hydroxyl radicals are produced that have strong oxidizing properties. Whereas; the dye photodegradation is negligible in the case of Fe 2 O 3 , and NiFe 2 O 4 catalysts at pH 10, due to the electrostatic repulsion between negatively charged catalyst surface and dye ions at high basic medium. While, in case of ZnFe 2 O 4 , the photodegradation reached only 40%.