Photocatalytic oxidation of the fungicide metalaxyl dissolved in water over TiO2

Metalaxyl (N-(2,6-dimethylphenyl)-N-(methoxy-acetyl)-D,L-alanine methyl est er, C15H21NO4) is extensively used as fungicide, and the resulting water co ntamination is a potential health hazard. The photocatalytic decomposition of this fungicide in aqueous suspensions containing TiO2 yields its complet e mineralization. The intermediates formed during the photomineralization a nd the reaction pathways were analyzed by recording proton NMR spectra. On the basis of the measurements of total organic carbon it was concluded that the rate of metalaxyl decomposition can be explained in terms of the Langm uir-Hinshelwood kinetic model and the values of the resulting constants wer e compared with those of some other organic compounds reported in the liter ature. (C) 1999 Elsevier Science Ltd. All rights reserved.