Síntese de óxidos de ferro magnéticos dopados com cobre ou níquel suportados em sílica: uso como catalisadores redox

Abstract

The study was conducted with the aim to propose a synthesis method for the preparation of magnetic iron oxides doped with copper or nickel to be supported on amorphous silica, in order to increase the catalytic activity in redox reactions and reduce the production cost of the catalyst. In addition, we studied the variation in the proportion (mol%) of dopant seeking structural changes to promote more active groups in their structures. The resulting materials were characterized by thermogravimetric analysis, we generated the correct temperature for the heat treatment, vibrational spectroscopy in the infrared region, which enabled the visualization of the silica bonds and some bands related to iron oxide, Raman spectroscopy, showing the possibilities occurrence of the dopant metals in the catalyst, diffraction X-rays, to infer on the phase of the iron oxide were formed and scanning electron microscopy and elemental analysis by energy dispersive X-ray, which showed us that there was no agglomeration in and the catalyst surface and showed that there are dopants in the material. The materials were tested for catalytic activity in oxidation reaction with methylene blue as a model organic compound via Fenton type and process type fotoFenton. The copper doped materials provided high capacity degradation in the presence of ultraviolet light across the reference compounds, materials doped with nickel reached an intermediate potential in these comparisons. The increased catalytic activity may be due to isomorphous substitution of certain atoms of iron by copper or nickel atoms produced deformities in the crystal structure and higher amounts of active sites on the surface of the material, which is kinetically favorable for Fenton chemistry. Thus it can be inferred that the process of doping of iron oxides together with the support, significantly increased the photosensitivity of the materials, in the same way as was increased activity regarding the process type Fenton in mass/mass iron proportion.