ADVANCED OXIDATION OF ATRAZINE IN WATER .2. OZONATION COMBINED WITH ULTRAVIOLET-RADIATION

The combination of ozone with ultraviolet radiation (254 nm) to oxidise atrazine is investigated. The importance of the three routes of atrazine elimination: direct photolysis, direct ozonation and hydroxyl radical oxidation is established in percentages. At neutral pH and 20 degrees C 87% of the oxidation rate is due to the radical way while direct ozonation only represents 1%. Mass transfer and kinetic data obtained in previous works [Beltran F. J., Ovejero G. and Acedo B. (1993) Wat. Res. 27, 1013-1021; Beltran F. J., Garcia-Araya J. F. and Acedo B. (1994) Wat. Res. 28, 2153-2164.] have been applied to mel. balance equations of atrazine, ozone (both in the gas and water) and hydrogen peroxide to obtain their corresponding concentrations in different conditions. It was necessary to include a hydroxyl radical initiating rate factor to account for radical ways not included in the basic mechanism of ozone decomposition. Comparison between different ways of oxidation and photolysis of atrazine (ozone, ozone/u.v. radiation, hydrogen peroxide/u.v. radiation) is also presented.