Degradation of the herbicides clomazone, paraquat and glyphosate by thermally activated peroxydisulfate

DIAZ KIRMSER, ELENA; DANIEL MARTIRE; GONZALEZ, MÓNICA C.; JANINA A. ROSSO

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2010 vol. 58 p. 12858 - 12862

0021-8561

Activated sodium peroxydisulfate has the potential to in situ destruct many organic contaminants due to the generation of the stronger oxidant sulfate radical. From photochemical activation of peroxydisulfate in flash-photolysis experiments, the bimolecular rate constants for the reaction of sulfate radical with glyphosate (1.6 108 M-1 s-1) and paraquat (1.2 109 M-1 s-1) were obtained at 25 °C. Thermal activation of peroxidisulfate was shown to degrade the herbicides clomazone, paraquat and glyphosate. Although the herbicide degradation was observed to take place in less than one hour, the mineralization of the organic carbon required longer reaction times, due to the formation of stable organic intermediates. For similar initial TOC values, TOC profiles were coincident for experiments with different substrates (the herbicides, humic acids and a mixture of glyphosate and humic acids), which indicates that the mineralization of all the samples is limited by the production of SO4.- radical. A linear correlation between the initial amount of SO4.- needed per mol of C and the average oxidation state (AOS) was found.