Chloride anion effect on the advanced oxidation processes of methidathion and dimethoate: Role of Cl2.- radical

PAULA CAREGNATO; JANINA A. ROSSO; JUAN M. SOLER; ANTONIO ARQUES; DANIEL O. MARTIRE; MONICA C. GONZALEZ

WATER RESEARCH

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2013 vol. 47 p. 351 - 362

0043-1354

The reaction of phosphor-containing pesticides such as methidathion (MT) and dimethoate(DM) with dichloride radical anions ðCl2 Þ was investigated. The second order rate constants (1.3 0.4) 108 and (1.1 0.4) 108 M1 s1 were determined for the reaction of Cl 2 with MT and DM, respectively. A reaction mechanism involving an initial charge transfer from the sulfide groups of the insecticides to Cl 2 is proposed and supported by the identified transient intermediates and reaction products. The formation of chlorinated byproducts was determined. The unexpected consequences of an efficient Cl 2 reactivity towards MT and DM on the degradation capacity by Advanced Oxidation Procedures applied to polluted waters containing the insecticides and Cl anions is discussed.