Rapid and facile chemical synthesis of Fe3O4/biochar nanocomposite for the adsorptive removal of fluoroquinolones from aqueous solution

In this study, iron oxide magnetic biochar-based composites were fabricated to investigate the adsorption efficiency of various fluoroquinolone antibiotics in aqueous systems. The present biochar was obtained by pyrolysis of oil palm empty fruit bunches (OPEFB) waste and modified with Fe3O4 nanoparticles to construct Fe3O4/biochar composite. The purity and distribution of the materials and their important chemical and physical properties are investigated using FTIR, scanning electron microscopy-energy dispersive X-ray spectroscopy, and XRD. From these characterizations, it is found that the modification of the biochar surface with Fe3O4 are successfully evidenced by: (1) an FT-IR peak at 586 cm−1 that is associated with the Fe-O vibration; (2) SEM-EDX demonstrating that iron and oxygen are evenly distributed on the surface, and 3) the crystalline structure of Fe3O4/biochar is confirmed by XRD results. Subsequently, the adsorptive ability of the composite towards various antibiotics, focusing on fluoroquinolones such as ciprofloxacin (CIP), norfloxacin (NOR), and ofloxacin (OFL), are determined. Parameters such as the ratio of biochar to Fe3O4, initial pollutant concentration, and catalyst dosage are evaluated to determine the optimal conditions. Although the optimal dosage for CIP, NOR, and OFL were determined to be 3.0 g/L, 2.0 g/L, and 4.0 g/L,respectively, the optimal concentration for all the fluoroquinolones is 5 ppm for 12 hrs adsorption. With these best conditions, the removal efficiency obtained for CIP, NOR and OFL are 95.0, 97.0, and 92.0 %, and the process fitted the pseudo-second-order kinetics model, respectively. The high removal efficiency recorded using Fe3O4/biochar is an indication of promising performance by the material in the remediation of wastewater contaminated by fluoroquinolones.