Multifunctional magnetic activated carbon for antibiotic capture and antibacterial activity: Influence of microwave, ultrasound, and classical dispersion methods

• Antibiotics were loaded on AC@Fe 3 O 4 via classical, ultrasonic, and microwave methods. • Microwave dispersion achieves highest antibiotic loading and antibacterial activity. • Recovered antibiotic-AC@Fe 3 O 4 composites show potent antibacterial effects. • Nanocomposites enable sustainable antibiotic reuse, reducing environmental pollution. • Antibiotic-loaded composites are magnetically separable and reusable. Antibiotic contamination in aquatic systems poses two major challenges: environmental pollution and the spread of antimicrobial resistance. In this work, magnetic activated carbon (ACF) obtained from olive stones and Fe 3 O 4 NPs was developed to address this issue by both capturing and reusing antibiotic molecules. Two widely used β-lactam antibiotics, ampicillin and benzathine penicillin G (BPG) were loaded onto ACF using three dispersion methods: classical, ultrasound, and microwave. Several characterization techniques including BET, XRD, FTIR, SEM, TEM, and AFM were used to confirm the mesoporous structure, magnetic separability, thermal stability and revealed the effective antibiotic adsorption. Microwave treatment provided the highest antibiotic loading and most homogeneous distribution, followed by ultrasonic and classical stirring. Antibacterial activity was evaluated against four pathogenic bacteria: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium . The antibiotic-loaded ACF exhibited inhibition zones close to those of free antibiotics despite containing significantly lower drug amounts. This efficiency is mainly attributed to uniform adsorption and controlled release from the ACF matrix, sustaining inhibitory concentrations over extended periods. Ampicillin-loaded composites displayed broader antibacterial spectra, whereas BPG composites were more effective against Gram-positive strains due to limited penetration of Gram-negative outer membranes. The dual function of these materials by recovering antibiotics from water and repurposing them as effective antibacterial agents offers an environmentally and economically sustainable strategy to reduce antibiotic pollution and combat bacterial contamination.