Electrochemical oxidation of carbamazepine in water using enhanced blue TiO2 nanotube arrays anode on porous titanium substrate

In this study, a blue TiO2 nanotube arrays anode on porous titanium substrate (Ti-porous/blue TiO2 NTA) was successfully fabricated by facile anodization and in situ reduction, and was used to investigate the electro-chemical oxidation of carbamazepine (CBZ) in aqueous solution. The surface morphology and crystalline phase of the fabricated anode were characterized by SEM, XRD, Raman spectroscopy and XPS, and the electrochemical analysis confirmed that blue TiO2 NTA on Ti-porous substrate had larger electroactive surface area, better electrochemical performance and higher center dot OH generation ability than that on Ti-plate substrate. The removal efficiency of 20 mg L-1 CBZ in 0.05 M Na2SO4 solution reached 99.75% at 8 mA cm-2 after 60 min electro-chemical oxidation, and the rate constant was 0.101 min-1 with low energy consumption. EPR analysis and free radical sacrificing experiments showed that center dot OH played a key role in the electrochemical oxidation. The possible oxidation pathways of CBZ were proposed through the identification of degradation products, and the main reactions may involve deamidization, oxidization, hydroxylation and ring-opening. Compared with Ti-plate/blue TiO2 NTA anode, Ti-porous/blue TiO2 NTA anode displayed excellent stability and reusability, and is promising to be used in the electrochemical oxidation of CBZ in wastewater.

Automated summary

In this study, a blue TiO2 nanotube arrays anode on porous titanium substrate (Ti-porous/blue TiO2 NTA) was successfully fabricated and used for the electro-chemical oxidation of carbamazepine (CBZ) in aqueous solution. The anode showed larger electroactive surface area, better electrochemical performance, and higher center dot OH generation ability compared to the Ti-plate substrate. The removal efficiency of CBZ reached 99.75% after 60 min with low energy consumption.