Influencia de la concentración de hierro sobre la actividad estructural, adsorción y la actividad fotocatalítica en la degradación de un colorante textil en catalizadores mesoporosos

Abstract

Mesoporous catalysts loaded with TiO2 and doped with iron were prepared using the sol-gel method. They were physically characterized showing that iron in their structures favored the formation of the crystalline phase anatase. The surface area for all iron doped catalysts decreased, but at the same time the iron presence increased pore volume and diameter obtaining catalysts with greater catalytic activity by the modification of the textural properties. The principal specie of iron was Fe2O3, determined by X-ray photoelectron spectroscopy (XPS). The catalysts were tested in the degradation of the Reactive Blue 69 (RB69) dye. Results confirm that increasing the concentration of iron on the surface of the catalysts increased the removal percentage of organic matter measured as total organic carbon (TOC) and chemical oxygen demand (COD). The iron in those catalysts was strongly linked on their surface, the iron in titanium dioxide (P25) lost huge quantity of it immediately passing to the water where it performed a photo-Fenton process. The best result for the dye degradation was obtained using the catalyst doped with the highest concentration of iron supported on Santa Barbara amorphous catalyst (SBA-15). This catalyst can be used during four cycles without losing catalytic activity. This result has a better performance than the P25 and the P25 doped with the same concentration of iron.