Oxidation of simazine: ozone, ultraviolet, and combined ozone/ultraviolet oxidation

A laboratory study was conducted to investigate the kinetics and byproducts of simazine oxidation by ozone, ultraviolet radiation (UV), and combined ozone and UV. Byproducts were identified by HPLC. Simazine was oxidized rapidly by ozone, UV, and ozone and UV. For example, 4 mg/L simazine disappeared completely after oxidation by 34 mg/min ozone at pH 7.2 for 15 minutes. Simazine disappearance rates during ozonation increased with applied ozone dose and pH. Dealkylation and dechlorination byproducts were formed, and deamination byproducts appeared at higher ozone doses or higher pH. During UV and ozone and UV oxidation, simazine disappearance rates increased with UV intensity. Dechlorination byproducts were formed by UV oxidation. Dealkylation, deamination, and dechlorination byproducts were formed by combined ozone and UV treatment. In comparing oxidation systems, simazine disappearance rates during ozonation at pH 9.9 were similar to those observed during ozone and UV oxidation.