Enhanced degradation of dimethyl phthalate in wastewater via heterogeneous catalytic ozonation process: performances and mechanisms.

Ozonation process is a promising yet challenging method for the removal of refractory organic matter due to the sluggish reaction for generating hydroxyl radical (˙OH) at a neutral pH condition. Herein, an efficient heterogeneous catalytic ozonation system using CeO 2 /Al 2 O 3 catalyst was developed to remove dimethyl phthalate (DMP) from wastewater. Under a neutral condition of pH = 6, this system achieved almost 100% DMP removal within 15 min at an optimized catalyst dosage of 30 g L -1 and the ozone flow rate of 22.5 mg min -1 . Moreover, the catalytic ozonation system exhibited a stable degradation performance of DMP in a wider pH range (pH = 5-10). The results of electron paramagnetic resonance (EPR) and quantitative tests confirmed the ultrafast conversion of O 3 to ˙OH (0.774 μM min -1 ) on the surface of CeO 2 based ceramic catalyst. The quenching experiments further supported the predominant role of ˙OH in the mineralization of DMP. These results highlight the potential of using the heterogeneous catalytic ozonation system for the efficient removal of refractory organic matter from wastewater.