Biogenic fabrication of biochar-functionalized iron oxide nanoparticles using Miscanthus sinensis for oxytetracycline removal and toxicological assessment

This study reports the green synthesis of biochar-coated iron oxide nanoparticles (BC-Fe₃O₄ NPs) using Miscanthus sinensis-derived biochar via a co-precipitation method. The resulting BC-Fe₃O₄ NPs were thoroughly characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), Thermogravimetric Analysis/Differential Thermal Analysis (TGA/DTA), and Brunauer-Emmett-Teller (BET), which confirmed the successful incorporation of Fe₃O₄ onto the biochar matrix, along with enhanced surface functionality and mesoporosity. Photocatalytic degradation tests demonstrated efficient removal of oxytetracycline (OTC), achieving up to 90% degradation within 60 minutes under UV irradiation, with optimal activity observed at mention pH and dosage. Antibacterial assays revealed significant inhibition zones against Escherichia coli and Serratia marcescens, especially during the initial two hours of treatment. Reusability assessments showed moderate regeneration efficiency across three cycles, whereas zebrafish embryo toxicity tests demonstrated a dose-dependent rise in developmental abnormalities, decreased hatching rates, and increased mortality. Overall, the findings suggest that BC-Fe₃O₄ NPs hold promise as an eco-friendly, cost-effective material for water purification, though further investigation into their long-term environmental safety.