: According to the results obtained thus far, ozone/magnetic copper ferrite nanoparticles (CuFe2O4 MNPs)/potassium hydrogen monopersulfate (KMPS) is capable of totally degrading 20 mg/L diazinon (DZN) with 6 mg/L ozone, 0.6 g/L KMPS, and 0.1 g/L MNPs at pH = 7 in 20 min. The experiments showed that the concentrations of KMPS and MNPs were more effective than ozone on the system efficiency. Moreover, high concentrations of KMPS and MNPs were not very effective in DZN degradation. Furthermore, the degradation efficiencies of diazinon at pHs 3, 4, 5, 6, 7, 8, 9, and 10 were 94%, 95.35%, 97.45%, 98.15%, 99.2%, 99.3%, 99.3%, and 100%, respectively. The pH of the solution was effective on the system so that in the range of 7 - 10, the system had high efficiency. Even within the range of 3 - 6, the pH had not been so plummeted, resulting in a high percentage of DZN degradation. Besides, MNPs could be utilized in the system for up to five cycles without any loss of catalytic activity. The degradation efficiency of diazinon was 99.2% in the first use and 92.1% in the fifth use. Also, the process efficiency was assessed in four real environments showing that agricultural drainage and urban wastewater with the degradation percentages of 79.1% and 77.3%, respectively, were better treated than the urban and river water with the percentages of 93% and 88.4%, respectively. With the determination of active agents in the reaction using the scavenging agents, it was recognized that sulfate radicals, hydroxyl radicals, superoxide, and singlet oxygen contributed to DZN degradation. By the way, ozone was advantageous to both singlet oxygen and superoxide in the degradation of diazinon.
