Abstract
The degradation effect, degradation mechanism, oxidation kinetics, and degradation products of Atrazine (ATZ) by Ultrasound/Peroxymonosulfate (US/PMS) in phosphate buffer (PB) under different conditions were studied. It turned out that the degradation rate of US/PMS to ATZ was 45.85% when the temperature of the reaction system, concentration of PMS, concentration of ATZ, ultrasonic intensity, and reaction time were 20 °C, 200 μmol/L, 1.25 μmol/L, 0.88 W/mL, and 60 min, respectively. Mechanism analysis showed that PB alone had no degradation effect on ATZ while PMS alone had extremely weak degradation effect on ATZ. HO• and SO4−• coexist in the US/PMS system, and the degradation of ATZ at pH7 is dominated by free radical degradation. Inorganic anion experiments revealed that Cl−, HCO3−, and NO3− showed inhibitory effects on the degradation of ATZ by US/PMS, with Cl− contributing the strongest inhibitory effect while NO3− showed the weakest suppression effect. According to the kinetic analysis, the degradation kinetics of ATZ by US/PMS was in line with the quasi-first-order reaction kinetics. ETA with concentration of 1 mmol/L reduced the degradation rate of ATZ by US/PMS to 10.91%. Product analysis indicated that the degradation of ATZ by US/PMS was mainly achieved by dealkylation, dichlorination, and hydroxylation, but the triazine ring was not degraded. A total of 10 kinds of ATZ degradation intermediates were found in this experiment.
Highlights
Atrazine (ATZ) is one of the most widely used chemical herbicides in Asian and South American countries
According to the kinetic analysis, the degradation kinetics of ATZ by US/PMS was in line with the quasi-first-order reaction kinetics
Product analysis indicated that the degradation of ATZ by US/PMS was mainly achieved by dealkylation, dichlorination, and hydroxylation, but the triazine ring was not degraded
Summary
Atrazine (ATZ) is one of the most widely used chemical herbicides in Asian and South American countries. The domestic use amount of ATZ was about 1.8 × 106 kg in late 1990s and increased by an average of 20% each year [1]. At this level, the annual use amount of ATZ in China could reach 108 kg by the end of 2018. ATZ can transform through different environmental media by diffuse, volatile, surface runoff, leaching, dry and wet deposition, etc. The ways ATZ entering water mainly include surface runoff, leaching, and dry and wet deposition [2]. ATZ with concentration up to 108 μg/L has been
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