Continuous-flow ozonation over modified ceramsite: implications for the degradation of cation red x-GRL.

Catalytic ozonation has been widely used for refractory dye wastewater treatment due to highly reactive HO·. In this study, a kind of low-cost and environmental-friendly modified ceramsite sphere derived from pyrite cinder, silty clay and kaolin was prepared as ozonation catalyst. The degradation performances of cation red x-GRL were performed under a continuous mode. Being close to the practical treatment, continuous-flow ozonation study is vital for applying heterogeneous catalytic ozonation in wastewater treatment at a large industrial scale. Results showed that the absorption capacity of this modified ceramsite towards cation red x-GRL was confirmed to be slight. The mineralization efficiency was high, accounting for 48.0% of 200 mg/L cation red x-GRL at a constant flow rate of 0.18 L/min (hydraulic retention time = 16 min), while only 7.8% during ozonation alone. Furthermore, this novel catalytic ozonation can maintain high mineralization efficiency in a wide range of pH (3-10), which was ascribed to the synergistic catalytic performance of various oxides. The reaction mechanism is ascribed to the promotion of ·OH production from O3 molecules' decomposition. Moreover, ozone utilization efficiency at hydraulic retention time of 16 min during catalytic ozonation was 2.0 times as high as that during ozonation alone.