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

An emerging advanced oxidation process, namely ozone (O3)/peracetic acid (PAA) process, was systematically investigated for the abatement of atrazine (ATZ) in this research. Compared to O3 alone, the PAA in O3/PAA process significantly promoted the decomposition of O3, with a more than 3.5 times increase in the pseudo first-order rate constants (kobs) of the ATZ removal under the tested conditions. The removal of ATZ in O3/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 (center dot OH) was the major radical in this process (contribution of 60%-79%), while PAA-specific organic radicals (CH3C(O)OO center dot and CH3C(O)O center dot) played a minor role (contribution of 16%-35%). In addition, HCO3- was observed to inhibit the degradation of ATZ with a reduction of approximately 24% in the kobs, 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 O3/PAA process in comparison to O3 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 O3/PAA process, which can improve the comprehending and implement of this process for the degradation of trace organic pollutants in (waste)water purification.