Kinetics of simazine advanced oxidation in water

Comparison of the effects and kinetics of UV photolysis and four advanced o xidation systems (ozone, ozone/hydrogen peroxide, ozone/UV radiation and UV radiation/hydrogen peroxide) for the removal of simazine from water has be en investigated. At the conditions applied, the order of reactivity was ozo ne < ozone/hydrogen peroxide < UV radiation < ozone/UV radiation and UV rad iation/hydrogen peroxide. Rate constants of the reactions between ozone and simazine and hydroxyl radical and simazine were found to be 8.7 M(-1)s(-1) and 2.1x10(9) M(-1)s(-1), respectively. Also, a quantum yield of 0.06 mol. photon(-1) was found for simazine at 254 nm UV radiation. The high value of the quantum yield corroborated the importance of the direct photolysis pro cess. Percentage contributions of direct reaction with ozone, reaction with hydroxyl radicals and direct photolysis were also quantified.