Enhanced photocatalytic degradation of reactive blue 19 using zeolitic imidazolate framework-8 composited with Fe3O4/MnO2 heterojunction

The present study offers a novel recyclable Fe3O4/MnO2/ZIF-8 heterojunction photocatalyst for the degradation of reactive blue 19 (RB19) under visible light irradiation. The catalyst was facilely synthesized by depositing Fe3O4/MnO2 nanocomposite onto the surface of ZIF-8 and characterized by field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption–desorption isotherms and UV–vis spectroscopy. Morphology and structure characterization of the prepared photocatalyst indicated that polyhedral ZIF-8 (ca. 500 nm) was coated by MnO2/Fe3O4 nanorods. The synergy effect of Fe3O4/MnO2/ZIF-8 composite exhibited an excellent photocatalytic activity toward RB19 degradation of 99.5 % after 60 min of irradiation due to high surface area and heterojunction formation. According to scavenger tests, the photodegradation of RB19 dye over Fe3O4/MnO2/ZIF-8 was mainly contributed by OH and O2− reactive radicals. The kinetic study showed that the catalytic degradation of RB19 on Fe3O4/MnO2/ZIF-8 was better described by the first-order kinetic model. The new catalyst was easily recovered using an external magnetic field because of its magnetic properties. Besides, Fe3O4/MnO2/ZIF-8 showed high recyclability and stability, maintaining a high removal efficiency of 91.3 % even after ten repeated cycles. The overall results indicated that the fabricated composite can be used as an efficient photocatalyst for treating organic dyes in wastewater.