In this work, Cobalt-doped binary metal ferrite nanoparticles were synthesized and evaluated for dual-functionality: the photodegradation of metronidazole (MTZL) antibiotic and the inactivation of pathogenic bacteria. Characterization of the synthesized catalyst revealed a saturation magnetization (Ms) of 80.35 \(\:emu\:{g}^{-1}\) , a total pore volume of 298 \(\:\mu\:{m}^{3}{ng}^{-1}\) , and a specific surface area of 70.2 \(\:{cm}^{2}{mg}^{-1}\) . Photocatalytic experiments demonstrated that 10 mg of the catalyst achieved 92.8% degradation of MTZL after 6 h under UV irradiation in acidic media (pH 3) supplemented with 4 mmol L− 1 hydrogen peroxide (H2O2). To differentiate photocatalysis from physical adsorption—addressing the role of surface interactions—control experiments in the dark yielded 70.2% MTZL removal. Selectivity studies indicated that the presence of tylosin as a co-existing antibiotic (1000 and 500 ppb) reduced MTZL degradation efficiency by approximately 41% and 17.5%, respectively. Furthermore, the material exhibited potent antibacterial activity, inhibiting 1.0 × 107 CFU mL− 1 of Staphylococcus aureus and Escherichia coli within 3 h using dosages of 5.0 mg and 15.0 mg, respectively. Complementing the experimental findings, molecular docking simulations were employed to predict the interaction mechanisms between the Co-doped ferrite cluster and target bacterial proteins. The analysis revealed significant binding affinities (scores of -4.3 and − 4.4 kcal mol− 1), driven primarily by hydrogen bonding, electrostatic forces, and metal-residue interactions within the active pocket.
