Photocatalytic oxidation of the fungicide metalaxyl dissolved in water over TiO2

Metalaxyl (N-(2,6-dimethylphenyl)-N-(methoxy-acetyl)- , -alanine methyl ester, C15H21NO4) is extensively used as fungicide, and the resulting water contamination is a potential health hazard. The photocatalytic decomposition of this fungicide in aqueous suspensions containing TiO2 yields its complete mineralization. The intermediates formed during the photomineralization and 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 Langmuir–Hinshelwood kinetic model and the values of the resulting constants were compared with those of some other organic compounds reported in the literature.