Magnetic biochar derived from olive pomace for efficient tetracycline removal from water

The uncontrolled release of tetracycline (TC), a widely used antibiotic, poses a significant threat to aquatic ecosystems owing to its persistence and contribution to antibiotic resistance. In this study, a biochar adsorbent was synthesised from olive pomace (OBC) and further magnetically modified (MOBC) to enhance its removal efficiency for TC in water. The adsorbents were extensively characterised using FTIR, XRD, BET, TGA, and FESEM-EDX. Batch adsorption experiments were conducted to evaluate the influence of pH, dosage, contact time, temperature, and concentration on removal performance. MOBC exhibited a superior adsorption capacity (248.77 mg/g at 25 °C) and faster kinetics than raw biochar, mainly due to improved surface area, porosity, and magnetic functionality. The adsorption process followed pseudo-first-order kinetics and was best described using the Langmuir isotherm model. Thermodynamic analysis revealed that the process is spontaneous and exothermic, with physical interactions dominating the adsorption mechanism. The MOBC demonstrated promising reusability with high desorption efficiency using NaOH and maintained substantial performance in real water matrices. These results highlight MOBC as a low-cost, sustainable, and efficient adsorbent for pharmaceutical contaminant removal in environmental remediation applications.