Photocatalytic degradation of pesticide methomyl: determination of the reaction pathway and identification of intermediate products.
Photochem Photobiol Sci
; 5(5): 477-82, 2006 May.
Article
en En
| MEDLINE
| ID: mdl-16685325
ABSTRACT
The degradation of pesticide methomyl in aqueous solution by UV-irradiation in the presence of TiO2 "Degussa P-25" has been studied. It was found that mineralisation to carbon dioxide, water, sulfate and ammonia took place during the process. The rate of photodecomposition of methomyl was measured using high performance liquid chromatography (HPLC), while its mineralization was followed using ion chromatography (IC), and total organic carbon (TOC) analysis. The identification of reaction intermediate products was carried out using coupled techniques HPLC-MS (electrospray ionization in positive mode) and a degradation pathway was proposed. Under our conditions, complete disappearance of 1.23 x 10(-4) mol l(-1) of pure pesticide occurred within 45 min of illumination and 80% TOC removal occurred in less than 4 h. Three main intermediates were identified resulting from (i) the rupture of the ester bond (or the N-O bond), (ii) the hydroxylation of methyl group borne by the nitrogen atom and (iii) the product resulting from the decarboxylation of the oxidized hydroxylated methyl group (photo-Kolbe reaction). In order to be sure that the photocatalytic results were consistent, hydrolysis and photolysis tests were performed. Photocatalysis proved to be an excellent new advanced oxidation technology (AOT) to eliminate methomyl present in water.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Fotólisis
/
Rayos Ultravioleta
/
Insecticidas
/
Metomil
Tipo de estudio:
Diagnostic_studies
Idioma:
En
Revista:
Photochem Photobiol Sci
Asunto de la revista:
BIOLOGIA
/
QUIMICA
Año:
2006
Tipo del documento:
Article
País de afiliación:
Marruecos