Electrochemical degradation performance and mechanism of dibutyl phthalate with hydrophobic PbO2 electrode

A polytetrafluoroethylene (PTFE) doped PbO2 anode with a highly hydrophobicity was fabricated by electrodeposition method. In this process, vertically aligned TiO2 nanotubes (TiO2NTs) are formed by the anodic oxidation of Ti plates as an intermediate layer for PbO2 electrodeposition. The characterization of the electrodes indicated that PTFE was successfully introduced to the electrode surface, the TiO2NTs were completely covered with β-PbO2 particles and gave it a large surface area, which also limited the growth of its crystal particles. Compared with the conventional Ti/PbO2 and Ti/TiO2NTs/PbO2 electrode, the Ti/TiO2NTs/PbO2-PTFE electrode has enhanced surface hydrophobicity, higher oxygen evolution potential, lower electrochemical impedance, with more active sites, and generate more hydroxyl radicals (·OH), which were enhanced by the addition of PTFE nanoparticles. The electrocatalytic performance of the three electrodes were investigated using dibutyl phthalate (DBP) as the model pollutant. The efficiency of the DBP removal of the three electrodes was in the order: Ti/TiO2NTs/PbO2-PTFE > Ti/TiO2NTs/PbO2 > Ti/PbO2. The degradation process followed the pseudo-first-order kinetic model well, with rate constants of 0.1326, 0.1266, and 0.1041 h-1 for the three electrodes, respectively. The lowest energy consumption (6.1 kWh g-1) was obtained after 8 h of DBP treatment using Ti/TiO2NTs/PbO2-PTFE compared to Ti/TiO2NTs/PbO2 (6.7 kWh g-1) and Ti/PbO2 (7.4 kWh g-1) electrodes. Moreover, the effects of current density, initial pH and electrolyte concentration were investigated. Finally, the products of the DBP degradation process were verified based on gas chromatography-mass spectrometry analysis, and possible degradation pathways were described.