Heterogeneous Fenton oxidation of phenol photo-assisted with visible radiation in the presence of g-C3N4 catalysts modified with different iron phases

This work compared graphitic carbon nitride (g-C3N4) modified with different iron phases to maximize its catalytic response in the phenol degradation at circumneutral pH under visible irradiation (Xe lamps, 70 W) and H2O2. The semiconductor was modified with different iron phases either: (i) supported (Fen+/g-C3N4, Fe3O4/g-C3N4 and α-Fe2O3/g-C3N4) or (ii) doped (Fe-g-C3N4). The materials were characterized by AAS, DRIFTS, DR-UV–Vis, N2 adsorption, TGA, H2-TPR, XPS, and XRD. Fe-g-C3N4 degraded 85 % of phenol (45 min), mineralized 62 % of DOC (180 min), leaching negligible iron (0.00131 mg Fe/L) at 25.0 ± 0.2 °C and pH 7.0. At pH 3.0, both phenol degradation (90 min) and mineralization (210 min) reached 100 %. The highly specific location of the metal within the lattice of the semiconductor substantially improved the use of the visible-light-photogenerated electron-hole pairs by the heterogeneous Fenton catalytic system in comparison to the metal oxides deposited on its surface.