Synthesis of iron-modified biochar derived from sugarcane bagasse through two-step KOH activation for enhanced ciprofloxacin removal

Antibiotic contaminants in aquatic media pose a significant threat to both human health and environmental sustainability. This study investigated an effective approach for removing ciprofloxacin (CIP) from aqueous solutions utilizing iron oxide-modified biochar derived from sugarcane bagasse (BioKFe). The modified biochar exhibited exceptional properties, including a high specific surface area (525.07 m2/g), a substantial pore volume (0.29 cm3/g), and numerous functional groups on its surface. The results revealed a removal efficiency exceeding 95%, with nearly complete removal of CIP achieved in the presence of H2O2 through Fenton oxidation. The adsorption data were best described by the Langmuir model (R2 = 0.943) and pseudo-second-order kinetics (R2 = 0.988), indicating that the CIP removal followed a monolayer adsorption process primarily governed by physisorption. The adsorption process of CIP by BioKFe was exothermic, with a maximum adsorption capacity of 42.63 mg/g. The proposed mechanisms for CIP removal include pore filling, hydrogen bonding, electrostatic attraction, π-π interactions, and Fenton oxidation. These interactions contributed to the high efficacy of CIP removal, which was approximately 96%. Furthermore, the BioKFe exhibited high stability and reusability, maintaining above 70% of its removal performance after four cycles of use. These findings suggested that iron-based biochar from sugarcane bagasse is promising for wastewater treatment, offering an efficient, sustainable, and cost-effective approach.