Synthesis, characterization and evaluation of iron oxides and niobium in the removal of dyes in Fenton type reactions and photocatalysis

Abstract

In this work, catalysts based on niobium oxide modified with iron oxide were developed for the photocatalytic treatment of effluents contaminated with dyes. The catalysts were prepared, in different proportions of niobium and iron, using niobium ammonium oxalate salts, iron nitrate and ammonium acetate and calcination at 400 °C. The solids were characterized by X-ray diffraction, infrared spectroscopy with Fourier transform, measured at zero point charge and evaluated in adsorption, Fenton reaction type advanced oxidation and methylene blue heterogeneous photocatalysis. It was observed that the increase in niobium concentration increased the values of point of zero charge and decreased the reaction system final pH. The solid with Fe/Nb2 ratio showed the best performance as an adsorbent and in oxidation reaction, followed by the one with Fe / Nb1.5 ratio. The solids showed practically the same result (1.8 eV), in addition, the presence of iron niobite (Fe/Nb1) favored the photocatalytic system.