FERRIC ION PROMOTED PHOTODECOMPOSITION OF TRIAZINES

The aqueous photodegradation rates of the triazines atrazine, ametryn, prometon, and prometryn were greatly enhanced by the addition of 20-300-mu-M amounts of ferric perchlorate or ferric sulfate. The hydroxyl radical, HO., derived from the photoreaction of the complex Fe(OH)2+, is likely to be the active reactant. Known quenchers of HO. as well as constituents of buffers expected to react with HO. diminished the rate of reaction. Furthermore, photodegradation products of the atrazine/ferric iron system were the same as those for a Fenton reaction (known to involve HO.). In the absence of oxygen, the reaction rate decreased; it increased at higher added iron concentrations and decreased in natural water (vs distilled water), implying that some dissolved constituents found in natural waters had a retarding effect on the photodegradation by competing for OH.. Results obtained indicate that these iron salts may be of value in the cleanup of contaminated groundwaters.