Pharmaceuticals removal by synergistic adsorption and S-scheme photocatalysis using nano-CeO2-coupled Fe3O4 on a CTAB matrix and investigation of the nanocomposite's antibacterial and antibiofilm activities: intrinsic degradation mechanism

Abstract

In this study, a magnetic Fe₃O₄–CeO₂ nano-heterojunction was fabricated on an organic matrix cetyl trimethylammonium bromide (CTAB) using a sonochemical method. The resulting nanocomposites (NCs) were used for the synergetic removal of tetracycline by adsorption and photocatalysis and their antimicrobial applications were also investigated. The average diameter and zeta potential of the NCs were 46 ± 2 nm and −33.24 ± 1.34 mV, respectively. The presence of the CTAB matrix was verified by FTIR analysis. The adsorption of tetracycline on the NCs was well fitted to the Langmuir model. The maximal adsorption was noted at pH 5. The photocatalytic degradation of tetracycline (25 mg L⁻¹) by the NCs (10 mg L⁻¹) reached 96.6% in 3 h under visible-light irradiation. The photocatalysis mechanism followed the S-scheme by retaining the photo-excited e⁻/h⁺ pairs with strong redox potential. The particles exhibited excellent antibiofilm and antibacterial activities. There was increased ROS generation and lipid peroxidation in the bacterial species upon exposure to the NCs. The bacterial antioxidant defense systems were disturbed upon exposure to the NCs. Therefore, the as-prepared Fe₃O₄–CeO₂-CTAB NCs could be used as a promising candidate in wastewater treatment for disinfection applications and the adsorptive/photocatalytic removal of pharmaceuticals.