Degradation of phenol with heterogeneous catalytic ozonation enhanced by high gravity technology

Abstract

In order to intensify the mass transfer of ozone and improve organic mineralization efficiency of heterogeneous catalytic ozonation, a rotating packed bed (RPB) reactor with heterogeneous catalytic ozonation was performed to mineralize phenol wastewater with the Fe–Mn–Cu/γ-Al2O3 catalyst (Cat) as packing. The effects of the high gravity factor (β), liquid flow rate (QL), initial pH, inlet ozone concentration (CO3), and phenol concentration (Cphe) on the phenol mineralization were investigated. The experimental results determined the optimal process regime involving a high gravity factor of 40, a phenol concentration of 100 mg/L, an inlet ozone concentration of 60 mg/L, a gas flow rate of 60 L/h, an initial pH of 6 and liquid flow rate of 85 L/h. After the wastewater was treated for 30 min, the total organic carbon removal rate (ηTOC) reached 96.42%. Compared with the performance of the Cat/O3-BR (bubbling reactor) and RPB-O3 system, the high gravity technology could increase the ηTOC related with the phenol wastewater by 21% and 57.27%, respectively. Possible reaction mechanism of Cat/O3-RPB system was proposed to be hydroxyl radical oriented by adding tert-butanol reagent and electron paramagnetic resonance technology, and a plausible degradation pathway of phenol was proposed and discussed. In conclusion, it can be observed that the coupling of RPB and heterogeneous catalytic ozonation technology to mineralize phenol wastewater is an effective method.