White LED-based photocatalytic treatment using recoverable cobalt ferrite nanoparticles

Contamination of freshwater sources has been alarming due to the widespread use of toxic chemicals in various industries. Advanced oxidation processes (AOPs) such as photocatalysis are widely explored to tackle such problems. In photocatalysis, highly oxidative species such as hydroxyl radicals (*OH) are produced with the help of some semiconductor photocatalysts and light. A photocatalyst decomposes these toxic organic compounds in the presence of light. Spinel ferrite (MFe2O4, M = Co, Ni, Cu, Zn, etc.) materials are an important candidate as a photocatalyst due to their semiconducting behaviour and narrow optical bandgap. In this work, we have synthesized cobalt ferrite (CoFe2O4) nanoparticles using the sol-gel method and subsequently annealed at 500°C. The nanoparticles are characterized using X-ray diffraction, scanning electron microscopy, Raman, and Infrared spectroscopy for structural analysis. The band gap of the material is evaluated using UV-visible spectroscopy. The photocatalytic activity of the material is investigated using methyl orange and methylene blue aqueous solutions as a model dye and a low-power white LED as a light source. The material could decompose 95 % of the dye after 150 minutes of irradiation. Adding hydrogen peroxide further improves the decomposition rate, with over 90 % decomposition achieved within 90 minutes. Hydroxyl (*OH) radicals have been identified as the main reactive species. The recyclability tests have shown that the photocatalyst can be used multiple times without compromising efficiency.