Adsorption Isotherms and Kinetics of Acebutolol and Metoprolol on Magnetic Nanocomposite Fe₃O₄@MIL-101(Cr)

Contamination of water bodies by emerging pollutants such as β-blockers has been a global concern over the past few years. This is due to the bioaccumulative character of β-blockers in the aquatic systems, and their excessive usage might cause adverse effects on both humans and aquatic biota. A reusable and recyclable magnetic chromium-based MIL-101 (Fe₃O₄@MIL-101(Cr)) nanocomposite was used as an adsorbent for the removal of the selected β-blockers (acebutolol and metoprolol) from wastewater. The nanocomposite‘s structural, magnetic and surface properties were confirmed using various characterisation techniques. The equilibrium data indicated that the maximum adsorption capacities of Fe₃O₄@MIL-101(Cr) for acebutolol and metoprolol were 30.9 mg g⁻¹ and 28.3 mg g⁻¹, respectively. The isotherm and kinetic experimental data best fitted Langmuir isotherm and pseudo-second-order kinetics models. Obtained free energies using the Dubinin-Radushkevich model were above 8 kJ mol⁻¹, demonstrating that the interaction mechanism between β-blockers and the Fe₃O₄@MIL-101(Cr) nanocomposite was chemisorption. The prepared nanocomposite was then used to remove β-blockers from real samples, and maximum removal efficiencies (94.1–97.1 %) were obtained in the presence of co-existing species. The Fe₃O₄@MIL-101(Cr) hybrid showed great potential for efficient and facile removal of β-blockers from river water, effluent and influent wastewater samples.