ATRAZINE DEGRADATION BY OZONATION IN THE PRESENCE OF METHANOL AS SCAVENGER

Studies on atrazine ozonation performed in methanol containing solutio ns showed a strong influence of the methanol content which might favou r direct O-3 reactions as compared to processes induced by OH. radical s. The importance of the slackening effect on the degradation rate of atrazine (which demonstrates a scavenger activity) was evaluated in va rious solvent compositions and pseudo-kinetic constants k' were found to be in the 10(-3)-10(-2) s(-1) range. The appearence rate of deethyl atrazine as major oxidation product was thus also modified (k' values between 10(-4) and 10(-3) s(-1)). Several by-products were detected wh ich are either related to deethylatrazine (intermediates or oxidation products) or belong to competitive pathways. Among them, a number of f ormamides (a new class of atrazine ozonation products) were identified using MS and MS-MS techniques. These compounds are produced by oxidat ion of the N-ethylamino group likely through a non radicalar process. Deschloro-triazines were also characterized as structures whose format ion specifically depends on the presence of methanol.