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

Abstract

• The preparation of Fe-MnO X /AC by high gravity technology was firstly proposed. • Fe-MnO X /AC(RPB) had more uniform active components compared with Fe-MnO X /AC(STR). • The redox cycle of Mn(IV)/Mn(III) and Fe(III)/Fe(II) synergistically activated O 3. • The catalytic process followed ·OH mechanism and was verified by EPR technology. • The η TOC of Fe-MnO X /AC/O 3 (RPB) was 7% higher than that of Fe-MnO X /AC/ O 3 (STR). In this study, activated carbon (AC) -supported Fe-Mn oxides (Fe-MnO X /AC) were prepared by high gravity method for heterogeneous catalytic ozonation of phenolic wastewater. The properties, catalytic performance and mechanism of Fe-MnO X /AC were investigated. It was found that Mn and Fe were successfully loaded on the surface of AC in the form of Fe 2 O 3 , Fe 3 O 4 and MnO 2 . 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-MnO X /AC/O 3 (RPB) was increased by 56% and 7% compared with that by ozone alone and Fe-MnO X /AC/O 3 (STR), respectively. The treatment time was only 45 min for Fe-MnO X /AC(RPB) but 10 h for Fe-MnO X /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 O 3 . The electron paramagnetic resonance (EPR) detected the ·OH signal peak by comparing the intensity of free radicals. Fe-MnO X /AC(RPB) enhanced the production of ·OH from O 3 , supporting the catalytic mechanism of Fe-MnO X /AC(RPB) on O 3 . In conclusion, the high gravity method provides a new means for industrial production of supported catalysts.