Exploring Fe-doped Zeolitic Imidazolate Framework-8 for the Adsorptive Removal of Pharmaceutical Contaminant: Acetaminophen as a Model Pollutant

The occurrence of acetaminophen in aquatic ecosystems has raised environmental concerns due to its toxicity, persistence, and adverse effects. Conventional wastewater treatment plants fail to remove pharmaceutical contaminants like acetaminophen. To address this challenge, Fe-ZIF-8 was successfully synthesized via a facile room-temperature method and evaluated for acetaminophen adsorption from aqueous solution.Fe-ZIF-8 exhibited a well-defined polyhedral morphology, providing a large surface area.The porous framework facilitated the efficient diffusion of acetaminophen molecules, while incorporating Fe ions introduced active catalytic sites, improving adsorption efficiency.Batch adsorption experiments revealed rapid acetaminophen uptake within the first 60 min, reaching equilibrium after 210 min under the optimum conditions of 0.012 g Fe-ZIF-8 in 300 mL of 100 mg L⁻¹ acetaminophen solution, with a maximum experimental adsorption capacity of 1165.82 mg g⁻¹. Kinetic analysis demonstrated that the adsorption process was best described by the non-linear pseudo-first-order model, while equilibrium data were better fitted by the Freundlich isotherm, indicating favourable adsorption on a heterogeneous surface. The Dubinin–Radushkevich model suggested that adsorption was predominantly governed by weak physical interactions. The outstanding adsorption performance of Fe-ZIF-8 is attributed to its high porosity, heterogeneous active sites, and synergistic π-π interactions, hydrogen bonding, and Lewis acid-base interactions between acetaminophen molecules and the Fe-modified framework. These findings demonstrate the considerable potential of Fe-ZIF-8 as an efficient and environmentally sustainable adsorbent for pharmaceutical wastewater remediation.