Novel magnetic g-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 composite for the very effective visible-light-Fenton degradation of Orange II.

A novel magnetic heterogeneous g-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 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-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 catalyst for the photo-Fenton degradation of Orange II in the presence of H 2 O 2 irradiated with visible light ( λ > 420 nm) at neutral pH was evaluated. The g-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 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)/H 2 O 2 ). The results indicated that successfully combining monodispersed Fe 3 O 4 nanoparticles and g-C 3 N 4 /α-Fe 2 O 3 enhanced light harvesting, retarded photogenerated electron-hole recombination, and significantly enhanced the photocatalytic activity of the system. The g-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 (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 α-Fe 2 O 3 and 2.65 times higher than the degradation rate constant for g-C 3 N 4 /α-Fe 2 O 3 under the same conditions. A reasonable mechanism for catalysis by the g-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 composite was developed. The g-C 3 N 4 /α-Fe 2 O 3 /Fe 3 O 4 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.