Fe3O4@SiO2 nanoparticles as a high-performance Fenton-like catalyst in a neutral environment

Abstract

Advanced oxidation processes (AOP) have been widely applied in water treatment. However, traditional Fenton reactions based on a Fe²⁺–H₂O₂ system requires an acidic environment and generates a large amount of Fe³⁺ ions. Herein, we reported that magnetic Fe₃O₄ core–SiO₂ shell nanoparticles (Fe₃O₄@SiO₂ NPs) could be used as a Fenton-like catalyst for the decomposition of H₂O₂, resulting in the decoloration of methylene blue (MB). Fe₃O₄@SiO₂ NPs had much higher activity than bare Fe₃O₄ cores, suggesting the coating of SiO₂ enhanced the catalytic activity. Most importantly, the best performance of Fe₃O₄@SiO₂ NPs was observed at neutral pH values. A higher temperature facilitated the diffusion of MB in solution, and thus, promoted the decoloration efficiency. The radical reaction nature was reflected by the electron spin resonance spectrum and the significant inhibition of the decoloration in the presence of the radical scavenger tertiary butanol. Fe₃O₄@SiO₂ NPs could be magnetically separated and partially regenerated after the decoloration. The implication for the applications of Fe₃O₄@SiO₂ NPs in water treatment is discussed.