Heterogeneous Fenton-like activity of novel metallosalophen magnetic nanocomposites: significant anchoring group effect

Abstract

Two new pyridine and thiolate anchoring groups were prepared to functionalize γ-Fe₂O₃ nanoparticles for coordinative attachment of simple Fe(III)- and Mn(III)salophen complexes. Four new magnetically recoverable composites were characterized by several analytical techniques such as FT-IR, XRD, TGA, EDS compositional analysis and VSM to confirm superparamagnetic properties. TEM images revealed the nanostructure nature of composites with size ranging between 20 and 40 nm. A heterogeneous advanced oxidation process for degradation of some organic dyes as water pollution compounds using an aqueous solution of H₂O₂ were successfully exploited. Several key parameters including the metal center in the salophen complex, initial pH, catalyst dosage, H₂O₂ and dye concentration and temperature were investigated. A significant effect of the anchoring ligand on the degradation efficiency and catalyst stability was documented. The superior catalytic activity and particularly durability of the thiolate-based catalysts were demonstrated in comparison with their Py counterparts. Rate constants of 0.21, 0.17, 0.23 and 0.11 min⁻¹ were obtained for degradation of rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and crystal violet (CV). Finally, a photoluminescence probing technology and radical scavenging measurements were carried out to elucidate the active species involved in the process.