Photocatalytic removal of the insecticide fenitrothion from water sensitized with TiO <inf>2</inf>

Abstract

The photocatalytic removal of the insecticide fenitrothion (IUPAC name: O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate), C 9 H 12 NO 5 PS, from water suspension of TiO 2 , was investigated by following the disappearance of the original substance along with the formation and disappearance of intermediates via recording NMR ( 1 H and 31 P) and UV spectra, as well as by pH measurements. Based on the obtained data, a possible reaction mechanism was proposed. It was found that 31 P-NMR spectrometry can be successfully used to follow the kinetics of transforming organic into inorganic phosphorus in the course of the degradation (k a =9.2×10 -7 mol dm -3 min -1 , r=0.980 for the illumination period after 15 h). The rate of fenitrothion aromatic ring decomposition was followed by UV spectrometry during the illumination (k a =3.1×10 -6 mol dm -3 min -1 , r=0.989). The complete mineralization was attained after about 66 h of irradiation. © 2003 Elsevier B.V. All rights reserved.