Preparation and characterization of cerium-doped multiwalled carbon nanotubes electrode for the electrochemical degradation of low-concentration ceftazidime in aqueous solutions

A modified multiwalled carbon nanotubes (MWCNTs) electrode doped with a rare earth metal, cerium, was prepared by electrodeposition. Scanning electron microscopy showed that cerium doping altered the microstructure and crystal orientation of the electrode surface, and the resulting electrode displayed a uniform and compact morphology. X-ray diffraction and X-ray photoelectron spectroscopy confirmed the successful deposition of CeO2 on the MWCNTs substrate. Cyclic voltammetry indicated that ceftazidime degradation on the modified MWCNTs electrode was irreversible. The Tafel curve showed that the modified electrode had a relatively high positive corrosion potential and a relatively low corrosion current density, indicating that the modified electrode could sustain a certain degree of corrosion. The degradation effects of the modified MWCNTs electrode on ceftazidime were evaluated systematically under different current densities, initial pH, supporting electrolyte concentration, electrode spacing, and initial ceftazidime concentration. The results suggested that the removal efficiency of ceftazidime with an initial concentration of 1 mg L−1 was approximately 100% after 60 min electrolysis in a 1 g L−1 Na2SO4 supporting electrolyte solution with a current density of 3 mA cm−2 and an electrode spacing of 1 cm. The possible mechanism of ceftazidime degradation was monitored by liquid chromatography-mass spectrometry.