Degradation of ciprofloxacin antibiotic using photo-electrocatalyst process of Ni-doped ZnO deposited by RF sputtering on FTO as an anode electrode from aquatic environments: Synthesis, kinetics, and ecotoxicity study

Abstract

In the current study, a novel electrode comprising of Ni-doped ZnO on a fluorine-doped tin oxide (FTO) glass was successfully applied as a photo-anode electrode to degrade ciprofloxacin (CIP) in synthetic solutions under ultraviolet A (UV-A) irradiation. In the first step, Ni-doped ZnO, deposited on an FTO glass (the synthesized photoanode electrode), via a radio-frequency (RF) sputtering technique. Morphological and structural analyses of synthesized composites were performed utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques, while the optical assets were investigated by diffuse reflectance spectroscopy (DRS) technique. The effects of variables such as pH [3–11], applied current (0.625–1.87 mA/cm2), initial concentration of CIP (5–50 mg/l), and reaction time (0–120 min) on CIP removal efficiency were investigated in a batch photo-reactor. Based on the results, suitable degradation of CIP (100%) was observed when the applied current was 1.87 mA/cm2, pH was 7, initial CIP concentration was 5 mg/L, and NaCl concentration as the electrolyte was 0.75 g/L after 90 min under UV-A (ƛ = 390 nm). The kinetic study was based on the first-order kinetics. Under optimal conditions, 83.7% of the initial total organic carbon (TOC) was removed. The application of electrolysis and photolysis processes led to a 2.04-fold synergistic effect in the CIP removal efficiency. Finally, the results showed that the photoelectrocatalysis process could significantly improve CIP degradation that could be used in the treatment of wastewater containing pharmaceutical compounds, such as CIP.