Synthesis and Characterisation of Fe3O4 Nanoparticles for Photo-Fenton Degradation of Methylene Blue Dye

Abstract

Developing efficient and recyclable photocatalytic materials for dye degradation is therefore of significant importance. In the present work, magnetite (Fe₃O₄) nanoparticles were synthesised via chemical co-precipitation using FeCl₃·6H₂O and FeCl₂·4H₂O as precursor salts. The XRD patterns confirmed the formation of crystalline Fe₃O₄ with a characteristic spinel structure. Optical analysis revealed a pronounced absorption in the ultraviolet region centred near 320 nm, corresponding to an estimated band-gap energy of 3.80 eV. SEM micrographs demonstrated the formation of irregularly distributed mesoporous particles, which provide a high surface area favourable for catalytic applications. The photo-Fenton catalytic performance of the synthesized Fe₃O₄ nanoparticles was evaluated by employing methylene blue (MB) as the target contaminant. Furthermore, optimisation of operational parameters showed that a catalyst loading of 60 mg per 100 mL solution, combined with the addition of 20 μL of 30% H₂O₂, resulted in nearly complete degradation (99%) of methylene blue within 30 min, with a rate constant of 0.0269 min⁻¹. These findings demonstrate that the synthesised Fe₃O₄ nanoparticles possess significant potential as efficient, magnetically recoverable photocatalysts for wastewater purification and the treatment of dye-contaminated water.