Synthesis and characterization of magnetic iron sulfide (Fe-S)/CuS nanocom-posite as a novel recyclable catalyst in photocatalyst removal of tetracycline from aqueous solutions

Drugs, especially antibiotics, as a group of emerging contaminants, pose a serious threat to the envi-ronment and aquatic ecosystems due to their adverse effects, cumulative properties, and develop-ing drug resistancy. Therefore, this study aimed to evaluate the removal efficiency of tetracycline (TC) antibiotic from aqueous solutions using photocatalytic process in the presence of magnetic iron sulfide (Fe-S/CuS) nanoparticles on a laboratory scale. The magnetic nanocomposite was first characterized by transmission electron microscopy, X-ray diffractometer, vibration sampling mag-netometer, Field-emission scanning electron microscopy, Fourier-transform infrared spectrometer, diffuse reflection spectroscopy, and energy-dispersive X-ray spectroscopy techniques. Factors, such as pH, reaction contact time, nanocomposite dose, and contaminant concentration on the removal efficiency were studied. All the experiments were performed at room temperature under UV-A light. The results of this study indicated that the highest removal efficiency of TC was obtained at opti-mum pH of 7. The results also showed that in the initial concentration of TC antibiotic (20 mg/L), the removal efficiency increased by increasing contact time and also by increasing the dose of the desired nanocomposite, the removal efficiency first increased and then decreased. Moreover, the synthesized nanocomposite had the ability to be reused with an 18% reduction in the removal effi-ciency in five consecutive cycles. Finally, the results of this study showed the acceptable efficiency of Fe-S/CuS nanocomposite in photocatalytic removal of TC antibiotic.