Insights into the novel oxidation process of ozone/peracetic acid: Kinetics evaluation, degradation pathways, and toxicity assessment

An emerging advanced oxidation process, namely ozone (O 3 )/peracetic acid (PAA) process, was systematically investigated for the abatement of atrazine (ATZ) in this research. Compared to O 3 alone, the PAA in O 3 /PAA process significantly promoted the decomposition of O 3 , with a more than 3.5 times increase in the pseudo first-order rate constants ( k obs ) of the ATZ removal under the tested conditions. The removal of ATZ in O 3 /PAA process was highly pH-dependent and significantly affected by the PAA dose and solution pH, with the best degradation performance achieved at a PAA dosage of 10 mg L −1 and pH of 8. The identification experiments of active species and probe experiments showed that the hydroxyl radical ( OH) was the major radical in this process (contribution of 60%−79%), while PAA-specific organic radicals (CH 3 C(O)OO and CH 3 C(O)O ) played a minor role (contribution of 16%−35%). In addition, HCO 3 − was observed to inhibit the degradation of ATZ with a reduction of approximately 24% in the k obs , and the removal efficiency of ATZ was inhibited by 31%−48% in the presence of humic acid and the actual water column. Two unique transformation products (TPs) were detected in O 3 /PAA process in comparison to O 3 alone, and the toxicity analysis using ECOSAR software revealed that all the TPs of ATZ were less toxic than their parent compound. In summary, this study demonstrated the outstanding performance of O 3 /PAA process, which can improve the comprehending and implement of this process for the degradation of trace organic pollutants in (waste)water purification.