Photocatalytic performance of a nickel ferrite/chitosan/bismuth(III) oxyiodide nanocomposite for metronidazole degradation under simulated sunlight illumination

Pharmaceutical waste is a source of dangerous pollutants that can be carcinogenic to humans. Therefore, the removal of these residues from wastewater is a priority in environmental engineering. In this study, we evaluated the performance of a FeNi3/chitosan/BiOI nanocomposite as a photocatalyst for metronidazole (MTZ) degradation under simulated sunlight. The morphological and structural properties of the nanocomposite were determined using advanced characterization techniques including X-ray diffractometry, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, diffuse reflectance spectroscopy, and vibrating-sample magnetometry analyses. The kinetics of MTZ degradation and the effect of physicochemical parameters such as pH (3-11), reaction time (5-200 min), initial MTZ concentration (10-30 mg/L), and catalyst dosage (0.005-0.1 g/L) on the MTZ degradation process were studied. The applied treatment process achieved 100% MTZ degradation under the following conditions: pH = 7, FeNi3/chitosan/BiOI dose = 0.04 g/L, MTZ concentration = 20 mg/L, and reaction time = 200 min. The used catalyst can be regenerated and reused six times with only slight losses in its activity. The final by-products of MTZ degradation were mineralized products. Therefore, the FeNi3/chitosan/BiOI nanocomposite used in the present study for MTZ removal is a promising practical catalyst.