Adsorption Performance and Mechanism of Iron-Modified Sugarcane Bagasse Biochar for Amoxicillin in Aqueous Solution
The overuse of antibiotics has led to residual amoxicillin (AMX) in aquatic environments, promoting the spread of antibiotic resistance genes (ARGs) and threatening ecological safety. In this study, magnetic iron-modified biochar (Fe-BC) was prepared from agricultural waste sugarcane bagasse via FeCl3·6H2O impregnation and oxygen-limited pyrolysis. The adsorption performance and mechanism of Fe-BC for AMX were systematically investigated. Under conditions of 25 °C, pH 6, and initial AMX concentration of 50 mg·L−1, the adsorption capacity reached 32.61 mg·g−1. Characterization of Fe-BC before and after adsorption, combined with adsorption kinetics, isotherms, and thermodynamic analyses, revealed that adsorption primarily relied on oxygen-containing functional groups. The mechanisms included pore filling, electrostatic interaction, hydrogen bonding, complexation, and π–π interaction. After six thermal regeneration cycles, the removal efficiency of AMX remained above 76%. The specific surface area of Fe-BC increased from 279.20 m2·g−1 to 481.42 m2·g−1, an enhancement of approximately 72.4%. These results provide a technical reference for the resource utilization of agricultural waste and cost-effective treatment of antibiotic-containing wastewater in rural decentralized areas.