Mixed metal ferrite (Mn0.6Zn0.4Fe2O4) intercalated g-C3N4 nanocomposite: efficient sunlight driven photocatalyst for methylene blue degradation

Abstract

Visible active mixed metal ferrite intercalated semiconductor photocatalyst Mn0.6Zn0.4Fe2O4/g-C3N4 was prepared via facile hydrothermal and liquid assembly method for methylene blue (MB) dye degradation. The prepared samples were well characterized in term of their functional groups, crystallinity, elemental analysis, surface morphology using Fourier transform infrared spectroscopy, x-ray diffraction spectroscopy, energy dispersive x-ray, and scanning electron microscopy, respectively. The optical response of catalysts was checked by estimating the energy band gap (E g) of semiconductor photocatalysts using UV-vis spectroscopy. The photoluminescence spectroscopy was also performed to estimate the reduction in emission intensity after insertion of g-C3N4 into Mn0.6Zn0.4Fe2O4. The novel composition of Mn0.6Zn0.4Fe2O4 with g-C3N4, improved the optical response of pristine photocatalysts due to the reduction in the energy band gap and insertion of heterojunction. The surface area analysis of Mn0.6Zn0.4Fe2O4 and Mn0.6Zn0.4Fe2O4/g-C3N4 were acquired by Brunauer-Emmett-Teller. Point zero charge was also determined to observe the surface behavior of composite under different solution pH. Various parameters such as pH, catalyst dose, oxidant dose, irradiation time and initial dye concentration were optimized, and their effects were studied in photo-Fenton process. It was observed that 98% MB dye was degraded under optimized conditions (pH = 8, composite dose = 50 mg/100 ml, oxidant dose = 7 mM, initial dye conc. = 10 ppm, and irradiation time = 120 min). The results showed that when the ferrites of mixed metals (Mn, Zn) were used with g-C3N4 their photocatalytic activity enhanced due to mutual effect of both mixed metals ferrite and g-C3N4, which is considerably higher than their individual effect already reported. Furthermore, the combined effect of independent variables was evaluated by response surface methodology.