Polyethylene glycol-assisted sol-gel synthesis of magnetic CoFe2O4 powder as photo-Fenton catalysts in the presence of oxalic acid

The aim of the study was to prepare magnetic photo-Fenton catalysts based on CoFe2O4 by polyethylene glycol-assisted sol-gel method for the degradation of methylene blue under UVA and visible light irradiation with H2C2O4 as a radical producing source. The catalysts were synthesized at different annealing temperatures in order to investigate the influence of annealing temperature on their crystal structure, morphology, surface functional groups, magnetic properties, and their photo-Fenton catalytic activity. According to the results, when the annealing temperature increased from 600 to 800 degrees C, the content of CoFe2O4 cubic spinel phase was significantly enhanced, the amount of Fe3+ ions in the tetrahedral sites also increased on the surface of samples, which improved the magnetic properties as well as the photo-Fenton catalytic performance under both UVA and visible light. However, at the annealing temperature of 900 degrees C, the photo-Fenton activity was declined, which can be attributed to the growth of catalytic particles and the decrease of Fe3+ ions on their surface. [GRAPHICS] . HighlightsPreparation of CoFe2O4 catalysts by polyethylene glycol-assisted sol-gel method.Increasing of annealing temperature improves the CoFe2O4 phase content.The Fe3+ ions in surface tetrahedral sites increases with annealing temperature.Enhanced CoFe2O4 phase and surface Fe3+ contents improve the photo-Fenton activity.H2C2O4 plays as an efficient radical source for the photo-Fenton catalysis.