Novel magnetic g-C3N4/alpha-Fe2O3/Fe3O4 composite for the very effective visible-light-Fenton degradation of Orange II

A novel magnetic heterogeneous g-C3N4/alpha-Fe2O3/Fe3O4 catalyst was successfully synthesized through a simple hydrothermal method. The structure, morphology, and optical properties of the catalyst were characterized. The photocatalytic activity of the heterogeneous g-C3N4/alpha-Fe2O3/Fe3O4 catalyst for the photo-Fenton degradation of Orange II in the presence of H2O2 irradiated with visible light (lambda > 420 nm) at neutral pH was evaluated. The g-C3N4/alpha-Fe2O3/Fe3O4 photocatalyst was found to be an excellent catalyst for the degradation of Orange II and offers great advantages over the traditional Fenton system (Fe(II/III)/H2O2). The results indicated that successfully combining monodispersed Fe3O4 nanoparticles and g-C3N4/alpha-Fe2O3/Fe3O4 enhanced light harvesting, retarded photogenerated electron-hole recombination, and significantly enhanced the photocatalytic activity of the system. The g-C3N4/alpha-Fe2O3/Fe3O4 (30%) sample gave the highest degradation rate constant, 0.091 min(-1), which was almost 4.01 times higher than the degradation rate constant for alpha-Fe2O3 and 2.65 times higher than the degradation rate constant for g-C3N4/alpha-Fe2O3/Fe3O4 under the same conditions. A reasonable mechanism for catalysis by the g-C3N4/alpha-Fe2O3/Fe3O4 composite was developed. The g-C3N4/alpha-Fe2O3/Fe3O4 composite was found to be stable and recyclable, meaning it has great potential for use as a photo-Fenton catalyst for effectively degrading organic pollutants in wastewater.