Manganese Oxide-Functionalized Palm Leaf Biochar for High-Efficiency Ciprofloxacin Adsorption from Water

The widespread occurrence of pharmaceutical contaminants, especially ciprofloxacin (CIP), in aquatic environments has created an urgent need for efficient and environmentally friendly water treatment strategies. In the present study, a green manganese oxide palm leaf biochar (MnO₂/PL biochar) nanocomposite was synthesized by depositing MnO₂ nanoparticles onto palm leaf-derived biochar utilizing Acacia nilotica pod extract as an eco-friendly reducing and stabilizing agent. Structural and surface characterization using SEM, EDX, FTIR, XRD, and BET verified the successful synthesis of the composite and revealed a substantial enhancement in its textural properties, leading to an approximately 42-fold increase in specific surface area, from 1.7 to 71 m²/g. The MnO₂/PL biochar exhibited excellent CIP adsorption performance, achieving 95% removal efficiency. The Langmuir model provided the best fit to the equilibrium data, indicating monolayer adsorption behavior, with a maximum adsorption capacity (Q_max) of 24 mg/g. The adsorption kinetics were most accurately described by the pseudo-second-order model (R² = 0.999), indicating that CIP uptake was governed by interactions with available active sites on the composite surface. The enhanced performance was attributed to the synergistic effects of the porous biochar structure and MnO₂ nanoparticles, which promoted multiple adsorption interactions. Furthermore, the regeneration study demonstrated that the MnO₂/PL biochar retained 81% of its initial CIP removal efficiency after four adsorption-desorption cycles, indicating good reusability and potential for repeated application. The MnO₂/PL biochar composite shows strong potential as a sustainable adsorbent for antibiotic removal from wastewater.