Trace Ti3+- and N-codoped TiO2 nanotube array anode for significantly enhanced electrocatalytic degradation of tetracycline and metronidazole

A trace Ti3+- and N-codoped TiO2 nanotube array (TiON) anode is fabricated by electrochemical reduction after introducing nitrogen into the TiON. The TiON anode material is characterized by scanning electron microscopy, X-ray diffraction, Raman spectra and X-ray photoelectron spectroscopy. Electrochemical analyses of TiON, including cyclic voltammetry, electrochemical impedance spectroscopy and linear scan voltammetry, are conducted to confirm that the electrochemical performance could be significantly improved by electrochemical reduction and N doping. The achieved TiON anode is applied to the electrocatalytic oxidation of tetracycline (TC) and metronidazole (MNZ). The effect of applied current density, initial solution pH and initial TC/MNZ concentration on the reaction kinetics is systematically evaluated to obtain the optimal conditions. The de gradation processes follow an apparent first-order kinetic model in all conditions. After 240 min of reaction time, the TC removal efficiency, chemical oxygen demand (COD) removal rate and total organic carbon (TOC) removal rate are > 99%, 92.86% and 74.98%, respectively. The MNZ removal efficiency, COD and TOC removal rate achieved are > 99%, 93.03% and 79.30%, respectively, after 240 min of degradation. The excellent removal efficiency of TC and MNZ indicates that this TiON anode is a promising material in the practical application of removing antibiotics from water.

Automated summary

In this study, a Ti3+- and N-codoped TiO2 nanotube array (TiON) anode was fabricated by electrochemical reduction, which showed significantly improved electrochemical performance in the electrocatalytic oxidation of tetracycline and metronidazole. The achieved TiON anode demonstrated high removal efficiency for both antibiotics, indicating its potential practical application in water treatment.