Degradation of phenol with Mn-CoOX/γ-Al2O3 catalytic ozonation enhanced by high gravity technology

Abstract

In this study, Mn-CoOX/γ-Al2O3 (MCA) was prepared by impregnation for catalytic ozonation of phenol in a rotating packed bed (RPB), and the effects of high gravity factor (β), liquid flow rate (QL), initial solution pH and gaseous ozone concentration (CO3) on the mineralization of phenol were explored. The results show that the degradation rate of phenol (ηphenol) reaches 100% at 9 min and the mineralization rate (ηTOC) reaches 95.01% at 45 min under conditions of β = 104, CO3= 80 mg L-1, QL = 80 L/h, and pH = 6. Compared with the bubbling reactor (BR)/MCA/O3 and O3/RPB systems, the ηTOC of the MCA/O3/RPB system is increased by 25.81% and 40.85%, respectively. The electron paramagnetic resonance (EPR) results reveal that hydroxyl radical (·OH) plays a critical role in the degradation of phenol by MCA catalyzed ozonation. The quenching experiment using tertiary butyl alcohol (TBA) as a scavenger of ·OH reveals that the ratio of direct and indirect degradation of phenol is 16:9. The intermediates generated during the degradation of phenol were detected by gas chromatography-mass spectrometry (GC–MS), and possible degradation pathways were proposed. In conclusion, MCA-catalyzed ozonation and RPB have a synergistic effect on ·OH initiation and improve the degradation and mineralization of phenol. This study provides a new perspective for the degradation of phenol.