Fast and Efficient Simultaneous Adsorption of Fluoroquinolone Antibiotics from Water Using CeO₂/Al₂O₃ Nanocomposites

The increasing residue of stable fluoroquinolone antibiotics, including levofloxacin (LFX) and ciprofloxacin (CFX), in the aquatic environment poses a significant challenge to the ecosystem. In the present study, CeO₂/Al₂O₃ nanocomposites were utilized for the fast simultaneous adsorption of CFX and LFX, while the adsorption was applicable for sample preconcentration and enrichment before analysis. The optimal conditions for the binary adsorption of LFX and CFX on CeO₂/Al₂O₃ were pH 6 and a contact time of 90 min. The adsorption processes of LFX and CFX on CeO₂/Al₂O₃ occurred on a heterogeneous surface and followed the Freundlich model. The maximum simultaneous adsorption capacities of LFX and CFX on CeO₂/Al₂O₃ were found to be 29.1 and 25.6 mg/g, respectively. Adsorption mechanisms of LFX and CFX on CeO₂/Al₂O₃ were governed by electrostatic interactions, hydrogen bonding, and hydroxylated active sites of CeO₂/Al₂O₃. The recovery performances in actual water samples of CFX reached 86.6%, confirmed with liquid chromatography with tandem mass spectrometry (LC-MS/MS), indicating that CeO₂/Al₂O₃ not only has potential in the simultaneous adsorption of FQs but also as an effective preconcentration step for trace antibiotic analysis in the water environment. This study highlights the competitive adsorption behavior in a binary system of FQs on CeO₂/Al₂O₃ and its implications for preconcentration applications.