Photocatalytic Evaluation of Mn and Ti-Modified SBA-15 Mesoporous Silica: a Prelude to Fine Tuning Their Radical Pathways

Abstract

Heterogeneous photocatalysis is a type of advanced oxidation process of high development in recent years because it allows the degradation and mineralization of organic pollutants by generating radical species on the surface of an irradiated semiconductor, without requiring other reactants. The most used semiconductor is TiO2 due to its physicochemical properties and cost. However, it is difficult to recover and requires high-energy irradiation to be photocatalytically active. TiO2 dispersion over the surface of an inert, high surface material such as mesoporous silica and co-modification with other transition metals have been proposed to improve TiO2 performance. SBA-15 mesoporous silica co-impregnated with Ti and different Mn loads were synthesized and evaluated in this study. The resulting materials were optically characterized by DRS and photocatalytically evaluated, monitoring the performance by electronic paramagnetic resonance spectroscopy (EPR) to determine their radical pathways. It was observed that the band gap of the materials decreases with higher Mn loads and they generate more reactive oxygen species (ROS), particularly superoxide radical.