MnFe2O4/ZrO2 nanocomposite as an efficient magnetically separable photocatalyst with good response to sunlight: preparation, characterization and catalytic mechanism

Abstract

Magnetically separable novel nano-MnFe2O4/ZrO2 nanocomposite (NC) and MnFe2O4 (MFO) samples were synthesized by an efficient solution combustion methodology. The structure, morphology and optical properties were characterized through powder X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy and UV–Vis spectroscopy. The photocatalytic activity of MnFe2O4/ZrO2 nanocomposite was analysed for decolourization efficiency of methylene blue (MB) and textile dye wastewater under natural sunlight irradiation. The results demonstrated that the decolourization response of the MnFe2O4/ZrO2 nanocomposite was 95% for MB and 59% for textile dye wastewater in 90 min. The photocatalytic performance of MnFe2O4/ZrO2 was almost 1.4 times as high as pure MnFe2O4 was ascribed to the synergic effect and interfacial interaction across MnFe2O4 nanoparticle (NP) and ZrO2 that leads to separation of electron–hole pairs efficiently and broadened light absorption of the composite (2.42 eV) compared to MnFe2O4 (2.15 eV). The effective optimized parameters such as solution pH of 7, nanocomposite dosage of 60 mg and initial dye concentration of 20 ppm were studied on photocatalytic performance for the removal of MB dye. The magnetically separable MnFe2O4/ZrO2 nanocomposite proved to be highly active and a stable catalyst in five successive photodecolourization cycles for an aqueous solution of MB dye under sunlight irradiation. Furthermore, the possible sunlight photocatalytic mechanism of the MnFe2O4/ZrO2 nanocomposite was proposed. Due to its enhancement in photocatalytic activity, this NC has great potential towards the environmental remediation for practical photocatalytic application towards wastewater treatment.