Kinetic mechanism of ozone activated peroxymonosulfate system for enhanced removal of anti-inflammatory drugs.

Peroxymonosulfate (PMS) was employed as an activator of ozone (O3) to degrade non-steroidal anti-inflammatory drugs (NSAIDs) (aspirin (ASA) and phenacetin (PNT)) in study. The combination of PMS in O3 system promoted the O3 decomposition and NSAIDs removal significantly. O3 molecule, hydroxyl radical (OH) and sulfate radical (SO4-) were responsible for the removal of target pollutants in O3/PMS system. The second-rate constants between O3, OH and SO4- with ASA were determined to be 7.32, 4.18 × 109 and 3.46 × 108 M-1·s-1, and 37.3, 4.99 × 109 and 5.64 × 108 M-1·s-1 for PNT, respectively. The pattern of pollutant removal and contributions of oxidative species were fitted by experiments and two models. Nevertheless, the wide variety of two models suggested that a comprehensive model for O3/PMS based on a first-principles approach was not yet possible, due to the number of radicals and subsequent chain reaction, such as SO5- or O3-. In addition, the formation of five typical CX3R -type disinfection by products was evaluated from post‑chlorine tests and theoretically calculation by frontier electron density calculation. The calculated toxicity of typical CX3R -type DBPs was found to decrease with the increase of pH. The results of this study provide a basis for exploring the mechanism of pollutant degradation in O3 system.