Preparation of Mn-FeOX/ZSM-5 by high-gravity method for heterogeneous catalytic ozonation of nitrobenzene

Abstract

Mn-FeOX/ZSM-5 is a good catalyst for wastewater treatment, but the conventional methods for preparing Mn-FeOX/ZSM-5 have the problems of non-uniform dispersion of active components and long preparation time. As the liquid-solid mass transfer process could be effectively increased in a high-gravity field, Mn-FeOX/ZSM-5 was prepared by high-gravity method in this study, and its properties were characterized by XRD, FTIR and SEM. The stability of Mn-FeOX/ZSM-5 and the loss of active components were investigated, and the mechanism of Mn-FeOX/ZSM-5 catalyzed the ozonation of nitrobenzene (NB) was also discussed. The results show that the specific surface area of Mn-FeOX/ZSM-5-h is 292.103 m2/g and the active components are well dispersed. Mn-FeOX/ZSM-5-h has the best catalytic activity under the conditions of precursor solution concentration = 0.3 mol/L, liquid flow rate = 60 L/h, and high gravity factor β = 30, and the removal efficiency of TOC reaches 87.5% within 25 min. The catalyst has good stability and only 1.10% of Mn and 0.63% of Fe are lost on average after 5 cycles. However, the removal rate of NB is significantly reduced with the addition of tert-butyl alcohol (TBA), implying that ·OH plays a dominant role in catalytic ozonation of NB by Mn-FeOX/ZSM-5. The electron paramagnetic resonance results confirm that ·OH is produced in the degradation process. In conclusion, Mn-FeOX/ZSM-5-h prepared by high-gravity method is a good catalyst for catalytic ozonation of NB because of its high catalytic activity and stability.