Preparation of Magnetic Fe3O4/MoO3/MCM-22 Photocatalyst and Its Study on Metronidazole Adsorption, Degradation, and Process Optimization

MCM-22 particles and molybdenum trioxide (MoO3) were prepared by hydrothermal method. MoO3 and iron oxide (Fe3O4) were loaded onto MCM-22 via wet inoculation. The prepared samples were used to removal metronidazole as one of the most widely used antibiotics from the solution media. The photocatalytic degradation of metronidazole was investigated by catalysts prepared in a batch reactor. The results revealed that Fe3O4/MoO3/MCM-22 catalyst with weight percentage of 0.25 : 1 : 1 had better efficiency in metronidazole removal. The response surface methodology (RSM) with Box Behnken design (BBD) with four variables was used to investigate the relationship between the obtained responses and process variables as well as to optimize the combinations with Design Expert software. The effects of time (min), pH, concentration of metronidazole (mg/L), Fe3O4/MoO3/MCM-22 catalyst with the weight percentage of 0.25 : 1 : 1 were evaluated at three levels. The software had the achieving the highest degradation efficiency of 99.98%, in optimal conditions with catalyst mass of 18.17 mg, time of 62.74 min, metronidazole concentration of 32 mg/L, and pH of 8.88. Also, isothermal studies indicated that the Tempkin equation with the highest correlation coefficient of 0.9479 had the highest agreement with the experimental data. The kinetic results demonstrated that the degradation of metronidazole by Fe3O4/MoO3/MCM-22 catalyst with a weight percentage of 0.25 : 1 : 1 with a pseudo-second order kinetic model was well described.