Very fast photodegradation of tetracycline by a novel ternary nanocomposite as a visible light driven photocatalyst

Highlights: • A novel visible driven nanophotocatalyst was synthesized and fully characterized. • Mechanism and products of tetracycline degradation were studied by UV–Vis and GC-Mass. • Photoelectrochemical and electrochemical properties were investigated. • Effect of process conditions on E_fb and N_D were extracted from Mott-Shotcky plots. • Surface resistance, capacity, and lifetime were obtained by Nyquist and Bode plots. Design and preparation of a novel Bi₂O₃/Bi₂S₃/BaFe₁₂O₁₉ ternary nanocomposite were reported. To investigate the straightforward preparation of Bi₂O₃/Bi₂S₃/BaFe₁₂O₁₉ ternary nanocomposite, different characterization methods including VSM, XRD, FESEM, UV–Vis DRS, EDX and ICP-OES were utilized. The as-prepared ternary nanocomposite was used as a photocatalyst for the photocatalytic degradation of tetracycline (TC) under incident visible light irradiation. To explore the efficiency of this research for the destruction of tetracycline, the effect of various essential and crucial parameters such as catalyst loading, pH of the solution, TC concentration, time of illumination, type of the catalyst, reusability function of the catalyst, turbidity of the solution in the presence of the catalyst and scavenger experiments were examined. Photocatalytic activity experiments displayed that the binary Bi₂O₃/Bi₂S₃ and ternary Bi₂O₃/Bi₂S₃/BaFe₁₂O₁₉ nanocomposites had very close photocatalytic activity (about 80% after 15 min under visible light irradiation). Due to the magnetic property and separability of Bi₂O₃/Bi₂S₃/BaFe₁₂O₁₉, it was selected for further study. The efficient and suitable photocatalytic performance of ternary nanocomposite can be attributed to the efficient separation of photo-generated electron-hole pairs, flat band potential, donor density, and polarization resistance of ternary nanocomposite evaluated by Mott-Schottky graphs and Nyquist, Bode plots extracted from electrochemical impedance spectroscopy. Different intermediates were produced at pHs 5, 7, and 11 which were characterized by GC-Mass but TC was mineralized completely after photodegradation. Trapping tests showed that the photo-generated HO^• and ¹O₂ are the main active species involved in the photocatalytic process. The durability test showed that the Bi₂O₃/Bi₂S₃/BaFe₁₂O₁₉ could be reused at least four times without substantial loss of activity.