Adsorption-enhanced catalytic wet peroxide oxidation of aromatic compounds on ionothermally synthesised copper-doped magnetite magnetic nanoparticles

Abstract

Environmental contextAromatic compounds are major organic pollutants that are hard to clean up by either adsorption or biological treatment processes. We synthesised Cu-doped Fe3O4 magnetic nanoparticles and showed that they efficiently degrade various aromatic compounds with H2O2 under mild conditions. This active and stabile heterogeneous Fenton-like catalyst has the potential for various environmental applications. AbstractMagnetite magnetic nanoparticles (Fe3O4 MNPs) have great potential in environmental remediation owing to the intrinsic peroxidase-like activity, which is unfortunately not strong enough to activate H2O2 for practical applications. Herein, Cu-doped Fe3O4 MNPs (Fe2.88Cu0.12O4) were ionothermally synthesised and demonstrated as a highly efficient and stable heterogeneous Fenton-like catalyst for the catalytic wet peroxide oxidation of aromatic compounds with H2O2 at pH ~7 and 25°C. Theoretical calculations found that the interaction between aromatic compounds (e.g. orange G) and Cu2+ through a terminal end-on binding mode with moderate strength was favourable to enhance their adsorption on Fe2.88Cu0.12O4. In addition, copper dopants increased the decomposition rate of H2O2 at 25°C about four-fold (0.584h−1 on Fe2.88Cu0.12O4 versus 0.153h−1 on Fe3O4), which is attributed to efficient redox cycling of iron and copper ions for synergistic activation of H2O2. Copper-enhanced adsorption of aromatic compounds, together with synergistic activation of H2O2 by surface iron and copper active sites, explained the higher catalytic activity of Fe2.88Cu0.12O4. This study provided new insight for improving the catalytic performance of magnetite-based heterogeneous catalysts for various environmental and biomedical applications.