Synergistic effect of O₃ and H₂O₂ on the visible photocatalytic degradation of phenolic compounds using TiO₂/reduced graphene oxide nanocomposite

rGOTi is a nanocomposite of reduced graphene oxide (rGO) and TiO₂ nanoparticles that was used in an advanced oxidation process to mineralize phenolic compounds in presence of oxidizing agents e.g., H₂O₂ and ozone. This rGOTi nanocomposite was prepared by a hydrothermal treatment method and characterized using many surface and bulk analysis techniques including X-ray photoelectron spectroscopy (XPS), Brunauer- Emmett-Teller (BET), UV-Vis diffuse reflectance spectroscopy (DRS) and Transmission Electron Spectroscopy (TEM). UV-Vis diffuse spectrum showed that the rGOTi exhibited absorption in the visible light range as the band gap energy was reduced from 3.11 to 2.96 eV. The kinetics of the degradation of phenol, p-chlorophenol (CP) and p-nitrophenol (NP) and their intermediates using the as-prepared nanocomposite photocatalyst compared to the bare TiO₂ nanoparticles was tested using Xenon lamps (mainly a visible light source) as a photoexcitation. It was revealed that the photocatalytic activity of the rGOTi is significantly higher than that of the TiO₂ nanoparticles. Furthermore, a tremendous increase in the photocatalytic degradation rates of all the phenolic compounds and their intermediates were observed when H₂O₂ and O₃ were simultaneously used where the degradation percentage of CP and NP within 20 min was close to 100%.