Manganese ferrite dispersed over graphene sand composite for methylene blue photocatalytic degradation

Magnetic materials can be considered as promising catalysts for the degradation of various organic pollutants in wastewater treatment as they can be easily separated with visible light response. The purpose of this research was to develop a highly efficient photocatalyst in decomposing methylene blue (MB) was synthesized using MnFe2O4 nanoparticles supported on graphene sand composite (MnFe2O4-GSC), resulting in an easily, magnetically separable and recyclable photocatalyst. MnFe2O4-GSC was prepared by a solvothermal methodology using commercial sand, graphene oxide (GO) and metal ions (Fe3+ and Mn2+) as precursor materials. The photocatalyst was characterized by scanning electron microscopy, X-ray diffraction, differential reflectance spectroscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy and zeta potential analysis. The results indicated that MnFe2O4 had a spherical shape with uniform size of about 200 nm were successfully loaded and dispersed on the graphene nanosheets and on the sand's surface. The photocatalytic performance of MnFe2O4-GSC for MB degradation under visible light irradiation was investigated with different reaction conditions, H2O2 concentration, catalyst dosage and pH. The use of the MnFe2O4-GSC as a heterogeneous photocatalyst achieved 100 % degradation of 10 mg L-1 of MB solution at natural pH (pH 7.65) in the presence of 5 mL of H2O2 and 180 min of contact time. In cyclic photodegradation experiments, the performance of MnFe2O4-GSC was stable and practically unchanged regarding its efficiency after five runs. Thus, this research provided a promising strategy for designing efficient and magnetically recyclable photocatalysts for decontamination of dye wastewater under visible light irradiation.