Heterogeneous photocatalytic degradation of metronidazole from aqueous solutions using Fe3O4/TiO2 supported on biochar

The Fe3O4/TiO2/BC composite was used as a photocatalyst to remove metronidazole from aqueous environments. The effect of different parameters such as pH, contact time, composite dose and initial metronidazole concentrations on the removal efficiency was investigated. Composite specifications were detected by field emission scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller and vibrating sample magnetometer analyses. pH = 7 was selected as the optimal value with respect to composite pH(zpc) and pK(a) values of the metronidazole. The metronidazole removal efficiency increased with increasing composite concentrations (0.25-0.35 g L-1). Also, the maximum efficacy was obtained at composite concentration of 0.35 g L-1. With increasing initial antibiotic concentration (10-40 mg L-1), the efficacy decreased from 100% to 80%. The kinetic data suggest that the photocatalytic removal of metronidazole followed the first-order kinetic model. A removal efficiency of 80% was maintained after five steps of composite application. The main mechanism involved in the photocatalytic removal of metronidazole is holes (h(+)), hydroxyl radicals (OH center dot), and superoxide radicals (O-2(-center dot)).