Magnetically separable Zn2FeO @CN microcubes derived from metal-organic frameworks for efficient tetracycline removal

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Removing tetracycline (TC) from water is vital for protecting both human health and aquatic life. One promising solution involves using magnetic carbon adsorbents derived from metal-organic frameworks (MOFs). In this study, we created a bimetallic MOF precursor, Zn2[Fe(CN)6]·3H2O (Zn/Fe-MOF), and applied a one-step pyrolysis process to produce Zn2FeOx@CN composite oxides with magnetic properties. This approach combines efficiency with practicality, offering a powerful tool for tackling water contamination challenges. The version of this adsorbent created at 500 °C, called Zn2FeOx@CN-500, demonstrated a strong ability to capture TC, with a capacity of 769 mg g-1, reaching equilibrium within just an hour at 298 K. This adsorbent remains stable across a wide pH range (3-11) and can work in various water conditions. Our analysis showed that the adsorption process is endothermic and involves a multilayer chemical adsorption, mainly driven by surface complexation, π-π stacking interactions, hydrogen bonding, and electrostatic attraction between Zn2FeOx@CN-500 and TC molecules. Moreover, Zn2FeOx@CN-500 can be easily separated magnetically and shows strong reusability, making it a practical choice for real-world water treatment applications.