Photoelectrochemical Degradation of Ibuprofen on a Titanium Dioxide Nanotube Photoanode

Titanium dioxide nanotube photoanodes were obtained by anodizing titanium foil at 60 V in an ethylene glycol-based electrolyte using a two-stage scheme with intermediate removal of the amorphous coating and subsequent annealing at 450 °C. The nanotubes consist of titanium dioxide in the form of anatase and have a length of 20–22 μm, an average diameter of 90–100 nm and a wall thickness of 20 nm. The activity of such a photoanode in the reaction of photoelectrochemical oxidation of ibuprofen (IBP) in the molecular and ionic form of potassium salt of 2-(4-isobutylphenyl)-propionic acid (2-(4-IBFPA) was studied. Regardless of the form of IBP, its photoelectrocatalytic oxidation on titanium dioxide nanotubes occurs with the intermediate formation of oxygenated forms of IBP. The results of intensity modulated photocurrent spectroscopy (IMPS) show that the addition of IBP to the 0.9% NaCl solution helps to suppress the recombination of electron-hole pairs due to the increased rate of charge transfer to the IBP. The TNT/Ti photoanode showed stable operation in the process of long-term photoelectrooxidation of IBP.