Evidence for the electrochemical production of persulfate at TiO2 nanotubes decorated with PbO2

Author(s)

Santos, Jose Eudes L. ^[1] ; Antonio Quiroz, Marco ; Cerro-Lopez, Monica ^[2] ; Chianca de Moura, Dayanne ^[1] ; Martinez-Huitle, Carlos A. ^{[1, 3]}

Affiliation

^[1] Univ Fed Rio Grande do Norte, Inst Chem, BR-59072970 Lagoa Nova, RN - Brazil

^[2] Univ Americas Puebla, ExHda, Grp Invest Energia & Ambiente, Sta Catarina Martir S-N, Cholula 72820 - Mexico

^[3] Univ Estadual Paulista, Natl Inst Alternat Technol Detect Toxicol Evaluat, Inst Chem, POB 355, BR-14800900 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: NEW JOURNAL OF CHEMISTRY; v. 42, n. 7, p. 5523-5531, APR 7 2018.
• Web of Science Citations: 7

Abstract

It is well known that PbO2-based electrodes are considered to be non-active anodes, producing higher concentrations of hydroxyl radicals in aqueous solutions, and consequently, favouring the electrochemical degradation of organic pollutants. However, no evidence has been reported on the production of persulfates using this kind of electrode in sulphate aqueous solutions. For this reason, the aim of this work is to prepare (by an electrochemical procedure (anodization and electrodeposition)) and characterize (by X-ray diffraction, scanning electron microscopy, and potentiodynamic measurements) Ti/TiO2-nanotubes/PbO2 disk electrodes (with a geometrical area of 65 cm(2)) in order to evaluate the electrochemical production of persulfate using Na2SO4 solution as the support electrolyte and applying current densities of 7.5 and 60 mA cm(-2), as well as the influence of the electrosynthesis of hydroxyl radicals, in concomitance. The results clearly showed that significant production of hydroxyl radicals and persulfate is achieved at the Ti/TiO2-nanotubes/PbO2 surface, but this depends on the current density. The production of (OH)-O-center dot at the Ti/TiO2-nanotubes/PbO2 surface in Na2SO4 solution was confirmed by a RNO spin trapping reaction. The results were compared with those of a Ti/Pt electrode in order to understand the effect when a lower amount of (OH)-O-center dot is produced at the active anode surface. Based on the results, the Ti/TiO2-nanotubes/PbO2 anode could exhibit good electrocatalytic properties for environmental applications involving persulfate oxidants. (AU)

• FAPESP's process: 14/50945-4 - INCT 2014: National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactivies
• Grantee: Maria Valnice Boldrin
• Support Opportunities: Research Projects - Thematic Grants