One-step fabrication of novel ultra porous Mn2O3-Fe2O3 @ SiO2: A versatile material for removal of organic pollutants from industrial wastewater at neutral pH

Abstract

In this study, a series of novel mesoporous Mn2O3-Fe2O3 @ SiO2.(MFS) nanocomposites were fabricated for the first time via the sol–gel/combustion method with different fuels, and various physicochemical characterization has been conducted. It was found that by introducing urea to the synthesis process, the surface area increased from 667.068 m2/g to 1752.154 m2/g, which is considerably higher than other silica-based catalysts in the literate. This can be attributed to the new synthesis protocol used in this study and the liberation of pore-making gases during the combustion process. Moreover, urea contains unshared electron pairs in nitrogen atoms and forms metal complexes, improving metal oxides bonds and enhanced nanocomposite structure. MFS (U) showed high adsorption efficiency and photocatalytic activity at neutral pH for 100 mg L−1 of Methylene blue (MB). Inorganic anions did not significantly affect the photocatalytic degradation process, and excellent stability and reusability were observed during 20 cycles. The main reactive species were revealed through the scavenger experiments following the order of •OH > h+, and a possible photocatalytic degradation mechanism for MB was also proposed. Additionally, degradation by-products analysis showed that the degradation was initiated by demethylation of the MB molecule, and MB was ultimately mineralized to CO2, H2O, and SO42−.