Preparation of Magnetic Biochar from Pomegranate Peel for Enhanced Norfloxacin Removal from Wastewater: Performance, Mechanism and Economic Analyses

The persistent presence of refractory antibiotics in the environment poses significant systemic risks to both ecosystems and public health. This study developed magnetic pomegranate peel biochar (MPBC) via KOH/Fe₃O₄ coimpregnation and pyrolysis to address norfloxacin (NOR) pollution. Characterized by a heterogeneous structure, MPBC exhibited a high surface area (895.43 m²/g) and magnetization (14.8 emu/g), enabling rapid magnetic separation. Batch experiments demonstrated that the adsorption kinetics and thermodynamic behavior of MPBC on NOR conformed more closely to the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum theoretical adsorption capacity, estimated using the Langmuir isotherm model, was 61.9 mg/g, which is 5.9 times greater than that of PBC. Through the characterization and analysis of the materials, the adsorption mechanism was investigated. It was found that the adsorption process primarily involved electrostatic interactions, π-π interactions, hydrogen bonding, and pore filling. MPBC retained 76.7% adsorption efficiency after five magnetic recovery cycles, showcasing robust reusability. In addition, economic analysis indicates that MPBC has a high cost-effectiveness ratio, with its comprehensive preparation cost ranging from $14.3-20.0/kg, which is comparable to that of commercial activated carbon. As a sustainable adsorbent derived from agricultural waste, MPBC combines high antibiotic removal efficiency with environmental remediation benefits. Its recyclability and magnetic separation capability offer a practical solution for mitigating refractory antibiotic pollution, aligning with circular economy principles and organic wastewater treatment needs.