Preparation of Fe-MnOX/AC by high gravity method for heterogeneous catalytic ozonation of phenolic wastewater

In this study, activated carbon (AC) -supported Fe-Mn oxides (Fe-MnOX/AC) were prepared by high gravity method for heterogeneous catalytic ozonation of phenolic wastewater. The properties, catalytic performance and mechanism of Fe-MnOX/AC were investigated. It was found that Mn and Fe were successfully loaded on the surface of AC in the form of Fe2O3, Fe3O4 and MnO2. The metal oxides were well dispersed and had a uniform particle size distribution, and the catalyst had a unique microporous structure. The mineralization rate of phenol by Fe-MnOX/AC/O3(RPB) was increased by 56% and 7% compared with that by ozone alone and Fe-MnOX/AC/O3(STR), respectively. The treatment time was only 45 min for Fe-MnOX/AC(RPB) but 10 h for Fe-MnOX/AC(STR). The high gravity technology enhanced the interphase mass transfer and the preparation efficiency of the catalyst because of its excellent micromixing performance. The XPS results showed charge transfer between Mn(IV)/Mn(III), Mn(III)/Mn(II) and Fe(III)/Fe(II). Mn(IV) and Fe(III) were the active sites that could generate oxygen vacancies to promote the adsorption and decomposition of O3. The electron paramagnetic resonance (EPR) detected the ·OH signal peak by comparing the intensity of free radicals. Fe-MnOX/AC(RPB) enhanced the production of ·OH from O3, supporting the catalytic mechanism of Fe-MnOX/AC(RPB) on O3. In conclusion, the high gravity method provides a new means for industrial production of supported catalysts.