Fe₃O₄ nanoparticles as an efficient heterogeneous Fenton catalyst for phenol removal at relatively wide pH values

In order to promote the practical application of the heterogeneous Fenton process in wastewater treatment, Fe₃O₄ nanoparticles were prepared and used to degrade organic pollutants efficiently over a wide pH range, using phenol as a model. During fabrication, the effects of Fe²⁺/Fe³⁺ ratio and thermal treatment temperature were investigated and optimized. Using a transmission electron microscope and X-ray diffraction, the nanoparticles were found in the form of Fe₃O₄ with an average size of 15 nm. The effects of Fe₃O₄ nanoparticle concentration H₂O₂ concentration, and pH on the removal efficiency and chemical oxygen demand (COD) abatement efficiency of phenol were investigated. Under optimized conditions, the nano-Fe₃O₄ heterogeneous Fenton system could achieve phenol and COD removal efficiencies of 100 and 70% respectively. This nanocatalyst was observed to have a high efficiency at a wider pH range (2–9), and a possible mechanisms for this effect was proposed.