Preparation of V2O5-ZnO coated carbon nanofibers: Application for removal of selected antibiotics in environmental matrices

The removal of ciprofloxacin (CIPRO) and cinoxacin (CINO) antibiotics from wastewater was investigated using V2O5-ZnO coated carbon nanofibers (V2O5-ZnO@CNF) as an adsorbent. The V2O5-ZnO@CNF nanocomposite was characterized using characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy/energy dispersion x-ray spectroscopy (SEM/EDX), and UV-vis spectrophotometry. The characterization results revealed that the V2O5-ZnO nanoparticles were incorporated on the surface of carbon nanofibers. The effects of different experimental parameters such as adsorbent amounts, contact time, initial pH, that affect the removal process were optimized using response surface methodology based on Box-Behnken design. The optimum conditions were found to be 018 g, 6.5 and 20 min for the adsorbent amount, sample pH and contact time, respectively. Under optimized conditions, the maximum adsorption capacity was found to be 71.4 and 87.7 mg g−1 for cinoxacin and ciprofloxacin, respectively. In addition, the adsorption isotherms and kinetics were used to investigate the adsorption mechanism. The data followed the order: Langmuir (R2 = 0.09942-0.9996) > Dubinin-Radushkevich (R2 = 0.9257-0.9557 > Temkin (R2 = 0.79991-0.9132),> Flory-Huggins (R2 = 0.7432-0.8813) > Freundlich (R2 = 0.7057-0.7808). Furthermore, the data was better described by pseudo- second-order kinetics, this implied that the adsorption process was dominated by chemisorption process as the rate-limiting mechanism through sharing or exchange of electrons between adsorbent and CIPRO or CINO.