ZnFe2O4 and COFe2O4 based heterojunction photo catalysts for photocatalytic dye degradation

Abstract

newline xv newlineABSTRACT newlineThe present research work has been focused on fabricating spinel ferrites based nitrogen doped graphene (NG) heterojunctions for environmental application. Zinc ferrite (ZF) and cobalt ferrite (CF) nanoparticles were successfully dispersed over nitrogen doped graphene (NG) sheets and coupled with semiconductors zinc oxide (ZnO), graphitic carbon nitride (GCN) and silver bromide (AgBr) to synthesize ZnO/ZF/NG, ZnO/CF/NG, GCN/ZF/NG, GCN/CF/NG AgBr/ZF/NG and AgBr/CF/NG nanocomposite using simple hydrothermal method. NG was synthesized through hydrothermal process by using graphene oxide and urea. The synthesized nanocomposites were successfully characterized by advanced spectral and microscopic techniques such as: scanning electron microscopy (SEM) which gathers the structural and morphological evidences of the nanoparticles, transmission electron microscopy (TEM) which described about the size, shape, morphology and crystalline nature of the nanoparticles, Fourier transform infrared spectroscopy (FTIR) for determination of chemical composition, X-ray diffraction (XRD) to study size and crystalline nature, X-ray photoelectron spectroscopy (XPS) to find out the essential composition, Brunauer, Emmett, and Teller (BET) analysis for determination of specific surface area, High performance liquid chromatography analysis (HPLC) was used for the examination of degradation products. newlinePhotocatalytic properties of ZnO/ZF/NG, ZnO/CF/NG, GCN/ZF/NG, GCN/CF/NG AgBr/ZF/NG and AgBr/CF/NG nanocomposites were analysed for the removal of organic azo dyes under visible light irradiation. The photodegradation process obeyed pseudo first order kinetics as verified by kinetic studies. The rate of photocatalysis was substantially influenced by adsorption of Malachite green (MG) and Methyl orange (MO) dyes onto ZnO/ZF/NG, ZnO/CF/NG, GCN/ZF/NG, GCN/CF/NG AgBr/ZF/NG and AgBr/CF/NG surface. The immediate adsorption and photocatalysis was most proficient process for elimination of selected azo compounds under visible light. The organic azo dyes were completely mineralized in 10 h. During disinfection mechanism, the effect of various radical scavengers revealed the pivotal role of hydroxyl radicals and superoxide radicals. The intermediate formation during the process of photodegradation was studied by HPLC and GC-MS analysis. ZnO/ZF/NG, ZnO/CF/NG, GCN/ZF/NG, GCN/CF/NG AgBr/ZF/NG and AgBr/CF/NG displayed considerable recycle effectiveness upto 10 catalytic cycles newlinexvi newlineduring photocatalytic process and was used as a stable photocatalyst for the treatment of industrial waste water. The high surface area of all the ternary photocatalysts was suitable for adsorptive removal of MO and MG dyes. Owing to recyclability, these ternary heterogeneous photocatalysts might be used as cost-effective for treatment of discarded water. The observations endorse that the synthesized ternary spinel ferrite photocatalysts impart significant contribution in wastewater decontamination using photocatalytic technology. newlineKeywords: Spinel ferrite, Heterogeneous photocatalysts, Nitrogen doped graphene, Photodegradation, Malachite green dye and Methyl orange dye.