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

In this study, Mn-CoO X / γ -Al 2 O 3 (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 ( Q L ), initial solution pH and gaseous ozone concentration ( C O 3 ${\text{C}}_{{\text{O}}_{\text{3}}}$ ) on the mineralization of phenol were explored. The results show that the degradation rate of phenol ( η phenol ) reaches 100% at 9 min and the mineralization rate ( η TOC ) reaches 95.01% at 45 min under conditions of β  = 104, C O 3 ${\text{C}}_{{\text{O}}_{\text{3}}}$ = 80 mg L -1 , Q L  = 80 L/h, and pH = 6. Compared with the bubbling reactor (BR)/MCA/O 3 and O 3 /RPB systems, the η TOC of the MCA/O 3 /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.