Degradation of methylene blue catalyzed by a photo-Fenton reaction of g-C <sub>3</sub> N <sub>4</sub> /Fe <sub>3</sub> O <sub>4</sub> nanocomposite with visible light
R. Avilés-Monreal, Alberto Cárdenas-Rodríguez, M.H. Farı́as, H.A. Borbón-Núñez, Felipe Castillón-Barraza
Abstract
Dye contamination in wastewater is a major environmental concern, particularly in industrial sectors such as textiles, food and pharmaceuticals. In this study, two-dimensional graphitic carbon nitride (g-C₃N₄) composites were synthesized via thermal polycondensation and subsequently exfoliated to enhance sheet dispersion. Exfoliated and unexfoliated g-C₃N₄ sheets were used as supports for Fe₃O₄ nanoparticle deposition via a co-precipitation method. The resulting g-C₃N₄/Fe₃O₄ nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy and X-ray photoelectron spectroscopy. The exfoliated g-C₃N₄/Fe₃O₄ composite showed superior photo-Fenton activity, achieving 90% degradation of methylene blue (20 mg/L) under visible light in the presence of H₂O₂ (2.5 mL) within 120 min. The composite exhibited a reduced band gap of 2.1 eV, compared to 2.7 eV for bulk g-C₃N₄. Kinetic analysis followed a pseudo-first-order model, with a rate constant of 0.0156 min−¹. Magnetic properties enabled rapid recovery and reuse, with the catalyst maintaining over 85% degradation efficiency after three consecutive cycles. Furthermore, the recovery and reuse of magnetic nanocomposites is facilitated by their inherent magnetic properties, rendering them a potentially viable solution for sustainable wastewater treatment in various industrial contexts.