Efeito do boro como promotor em óxidos de ferro: estudo da oxidação de compostos orgânicos modelo

Abstract

The aim of this study was to obtain iron oxides (goethite phase, α - FeOOH) for using as catalysts in reactions based of chemical Fenton in the catalytic oxidation of methylene blue and quinoline. Moreover, by means of the treatment with boric acid, it was attempted to surface modifications in order to improve the catalytic properties of the oxide through the generation of more active groups on the surface of goethites. The types of structures formed on the surface were investigated through the characterization by thermogravimetry analisys, scanning electron microscopy, spectroscopy vibrational infrared, spectroscopy Mössbauer, spectroscopy X-ray excited photoelectron, spectroscopy X-ray absortion and diffraction. The association of these techniques revealed the complexation of boric acid on the surface of goethites and partial reduction of some species of Fe(III) to Fe(II). When tested in the oxidation of organic compounds, the new class of iron oxide showed high capacity for degradation of organic components present in the solution. The increase in catalytic activity is assigned the role of boron as a promoter in the transfer of electrons from iron to hydrogen peroxide, and the presence of species of Fe(II), which are kinetically more favorable for Fenton’s reaction.