Abstract
Pharmaceutical residues, including a wide range of therapeutic drugs, have been increasingly reported in drinking water sources worldwide, raising environmental concerns due to their potential impact on aquatic ecosystems. Among the available treatment approaches, adsorption has emerged as one of the most reliable methods for eliminating these pollutants. In the present study, metformin was effectively removed from water using a nanocomposite adsorbent consisting of copper nanoparticles anchored onto magnetic chitosan (Cu@MCS). The removal of metformin by Cu@MCS was governed by several mechanisms: surface complexation with copper species, electrostatic interactions, hydrophobic associations between the drug's methyl groups and magnetite, and hydrogen bonding between metformin's amino groups and oxygenated functional groups of chitosan. The structural and surface properties of the nanocomposite were characterized through FTIR, XPS, XRD, SEM, and HRTEM analyses. Key experimental factors, such as initial drug concentration, contact time, pH, and ionic strength, were systematically optimized to maximize adsorption efficiency. Adsorption data closely followed the Langmuir isotherm model, with a maximum capacity (q(m);) of 52.91 mg·g(-1) at 298 K. Regeneration tests demonstrated excellent reusability, showing only a 3.7% decline in performance after six adsorption-desorption cycles. The Cu@MCS material also proved effective in removing metformin from diverse real water samples, including river water, wastewater, bottled water, and tap water. A notable advantage of this nanosorbent is its magnetic separability, which enables straightforward recovery from solution, even at low contaminant levels and with large sample volumes. These results underline the potential of magnetic chitosan-based nanocomposites as fast, efficient, and reusable adsorbents for the removal of pharmaceutical contaminants from aquatic systems.