Model applications and mechanism study on the degradation of atrazine by Fenton's system

Atrazine (ATZ), 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine, was effectively degraded by hydroxyl radicals that were generated by Fe-II/H2O2 in the Fenton's process. Up to 98% ATZ removal can be achieved in the process if the doses of Fe-II and H2O2 are selected appropriately. Oxidation capacity of the process was successfully predicted through a kinetic approach with three simple and measurable parameters (i.e., two rate constants and a break point time), which makes the model useful in predicting, controlling and optimizing the degradation of ATZ. In addition, the transformation pathways of ATZ decay was successfully investigated by using a novel technology, liquid chromatography electrospray tandem mass spectrometry (LC/ESI-MS/MS). Ten intermediates were identified in the process. The alkylic-oxidation followed by dealkylation and/or dechlorination-hydroxylation were found to be the major pathways of the decay of ATZ in Fenton's process. All the detected intermediates were found to be dealkylated in different levels or positions. The dealkylated species may be further dechlorinated but generally at a lower fraction (<10%) due to the depletion of oxidants. (C) 2004 Elsevier B.V. All rights reserved.