Electrochemical oxidation of triclosan using Ti/TiO2 NTs/Al-PbO2 electrode: reaction mechanism and toxicity evaluation

5-Chloro-2-(2,4-dichlorophenoxy) phenol (triclosan, TCS) is a potential threat to the environment and human health, and it needs appropriate approaches for its removal. A new modified PbO2 electrode, Al-PbO2 based on TiO2 nanotubes (NTs), was successfully prepared for TCS electrochemical oxidation. Scanning electron microscopy indicated a compact coating layer on the anode. TCS removal on Ti/TiO2 NTs/Al-PbO2 anode followed a pseudo-first-order kinetics. The electrical efficiency per log order (EE/O) for oxidation was decreased from 14.79 to 12.90 kWh m(-3) order(-1) after TiO2 NTs on Ti material and decreased to 8.27 kWh m(-3) order(-1) after Al3+ doping. The effects of current density, pH value, and electrolyte concentration were investigated. Intermediate organo-chlorinated compounds were detected by gas chromatography coupled with mass spectrometry, high-performance liquid chromatography, and ion chromatography. Finally, ecotoxicity assessment revealed that the degradation of TCS by electrooxidation system with Ti/TiO2 NTs/Al-PbO2 anode could yield a smaller toxicity compared with parent compounds.

Automated summary

A new modified PbO2 electrode (Al-PbO2) was successfully prepared for the electrochemical oxidation of TCS, showing a decrease in electrical efficiency per log order after TiO2 NTs attachment and Al3+ doping. The study investigated the effects of current density, pH value, and electrolyte concentration, and detected intermediate organo-chlorinated compounds. Ecotoxicity assessment revealed that the degradation of TCS by the electrooxidation system with Ti/TiO2 NTs/Al-PbO2 anode resulted in smaller toxicity compared to the parent compounds.