La2O3-CuO2/CNTs electrode with excellent electrocatalytic oxidation ability for ceftazidime removal from aqueous solution

Carbon nanotubes are recognized as an advanced anode material for electrocatalysis oxidation recalcitrant antibiotics in wastewater. In this study, a novel La2O3 -CuO2 /CNTs electrode was synthesized by solvothermal method and calcination in nitrogen atmosphere. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were conducted to illustrate the structure and elemental composition, and the La and Cu bimetallic composite oxide (La2O3 -CuO2) were observed on the surface of carbon nanotubes. Cyclic voltammetry analysis showed that the modified electrode had better catalytic activity and stable working lifetime. The Tafel curves indicated that the corrosion potential of the electrode increased while the corrosion current density decreased. The degradation of ceftazidime by modified electrode was studied through optimization of five parameters, including current density, electrode space, electrolyte concentration, pH and volume of solution. The results demonstrated that La2O3 -CuO2 /CNTs electrode exhibited the electrochemical degradation efficiency of 90% towards 1 mg L-1 ceftazidime within 30 min, which is much higher than those of pristine CNTs and dimensional stable anode. The optimal operating conditions were: volume of 100 mL, 1 g L-1 Na-2 SO4 as electrolyte, current density of 0.8mA-cm(-2) , and electrode space is 2 cm. The degradation intermediates and routes of ceftazidime under modified electrode were deduced by LC-MS analysis. These results suggest that La2O3 -CuO2/CNTs electrodes can be considered as promising catalysts for treating bio-refractory antibiotics with relatively low concentration.