RATE CONSTANTS FOR REACTION OF HYDROXYL R ADICALS WITH SOME DEGRADATION BY-PRODUCTS OF ATRAZINE BY O3 OR O3 H2O2

Rate constants for the reaction of hydroxyl radicals with some oxidati on by-products of atrazine by O3 or O3/H2O2 have been measured using c ompetitive oxidation experiments. Aqueous solutions containing two org anic solutes (2 oxidation by-products or 1 oxidation by-product + sodi um paranitrobenzoate as a competitor) and hydrogen peroxide have been oxidized by O3/H2O2 in a semi-batch reactor at 20 +/- 0,5-degrees-C an d pH almost-equal-to 7.5 - 8.1. The following second-order rate consta nts for the reaction of hydroxyl radicals were obtained: atrazine: k(A t) = 2.4 10(9) l mol-1 s-1; desethylatrazine: k(DEA) = 1.2 10(9) 1 mol -1 s-1; desisopropylatrazine: k(DIA) = 1.9 10(9) 1 mol-1 s-1; hydroxya trazine: k(HA) = 2.6 10(9) 1 mol-1 s-1. Moreover, desethyldesisopropyl atrazine (DEIA) and isocyanuric acid (IA) were found to be refractory to the oxidation by OH' radicals (k(DEIA) or k(IA) much less than 5 10 (7) 1 mol-1 s-1).