Water Research 2013-01-01

Chloride anion effect on the advanced oxidation processes of methidathion and dimethoate: role of Cl2(·-) radical.

Paula Caregnato, Janina A Rosso, Juán M Soler, Antonio Arques, Daniel O Mártire, Mónica C Gonzalez

Index: Water Res. 47(1) , 351-62, (2013)

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Abstract

The reaction of phosphor-containing pesticides such as methidathion (MT) and dimethoate (DM) with dichloride radical anions (Cl(2)(·-)) was investigated. The second order rate constants (1.3 ± 0.4) × 10(8) and (1.1 ± 0.4) × 10(8) M(-1) s(-1) 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.Copyright © 2012 Elsevier Ltd. All rights reserved.