Novel highly stable β-cyclodextrin fullerene mixed valent Fe-metal framework for quick Fenton degradation of alizarin

Abstract

β-Cyclodextrin (β-CD) supported magnetic nanoscaled fullerene/Fe₃O₄ (CDFMNPs) and fullerene/Fe₃O₄ (FMNPs) composites were prepared and characterized. These composites can be utilized as heterogeneous catalysts for the Fenton oxidation reaction to degrade alizarin in aqueous solutions. The saturation magnetization (M_s) value of quasi-spherical CDFMNPs was found to be 13.16 emu g⁻¹ and their diameter was in the range of 25–30 nm. The catalytic activities of the prepared materials were tested with varying conditions of pH, amount used and the concentration of H₂O₂ for degradation of alizarin at room temperature. The exceptionally high degradation efficiency of CDFMNPs was observed for alizarin at pH 3 with 2.0 g L⁻¹ catalyst and 25 mM of H₂O₂. The increased oxidative degradation efficiency is attributed mainly to the formation of active hydroxyl radicals (˙OH) on the surface of the catalyst, which are generated by the active decomposition of H₂O₂ by the solid heterogeneous catalyst and the promoting effect of β-CD. CDFMNPs can be magnetically separated and the catalyst was found to be reusable and stable for five successive runs with no significant loss of catalytic activity. In the magnetic environment of Fe₃O₄ nanoparticles, fullerene has a crucial role to enhance the activity by increasing the stability with nominal iron leaching. Based on mass analysis of alizarin degradation, the formation of aliphatic acids and monocyclic compounds through phthalic anhydride and di-methyl phthalate established the proposed degradation path.