Photocatalytic Degradation of Acid Orange 7 by Urea-Derived Exfoliated C3N4: Identification of Transformation Products and Reaction Pathway

The photocatalytic degradation of Acid Orange 7 (AO7) in aqueous solution in the presence of exfoliated C3N4 (n-C3N4) as a photocatalyst was investigated under simulated solar light irradiation. The n-C3N4 photocatalyst was synthesized by polymerization of urea as a precursor and characterized by UV/Vis and FTIR spectroscopy, and transmission electron microscopy. Degradation products were identified by high-performance liquid chromatography with high-resolution mass spectrometry (LC–HRMS). It was found that AO7 undergoes a series of oxidation steps mediated by radicals generated during light absorption by n-C3N4, as well as through a photosensitization process initiated by light absorption by AO7. This results in decolorization and the formation of aromatic and aliphatic intermediates, which undergo further oxidation to simpler compounds.