Degradation of the Herbicides Clomazone, Paraquat, and Glyphosate by Thermally Activated Peroxydisulfate

Abstract

Activated sodium peroxydisulfate has the potential to in situ destruct many organic contaminants because of 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 × 10(8) M(-1) s(-1)) and paraquat (1.2 × 10(9) M(-1) s(-1)) at 25 °C were obtained. Thermal activation of peroxydisulfate was shown to degrade the herbicides clomazone, paraquat, and glyphosate. Although the herbicide degradation was observed to take place in less than 1 h, the mineralization of the organic carbon required longer reaction times, because of the formation of stable organic intermediates. For similar initial total organic carbon (TOC) values, TOC profiles were similar for experiments with different substrates (the herbicides, humic acids, and a mixture of glyphosate and humic acids), which indicates that the mineralization of all of the samples is limited by the production of SO(4)(•) (-) radicals. A linear correlation between the initial amount of SO(4)(•) (-) needed per mole of C and the average oxidation state was found.

Synthesis of Magnetic Cobalt Nanoparticles Anchored on Graphene Nanosheets and Catalytic Decomposition of Orange II

“…Generally, Oxone is dissociated into SO 4 –• either through photolysis or thermolytic cleavage at high temperatures . Temperature usually has a significant influence on Oxone decomposition rate, which produces SO 4 –• .…”

“…Generally, Oxone is dissociated into SO 4 −• either through photolysis or thermolytic cleavage at high temperatures. 48 Temperature usually has a significant influence on Oxone decomposition rate, which produces SO 4 −• . The effect of the temperature on the rate of Orange II degradation by the Co− graphene/PMS system was studied in experiments performed at 25, 35, and 45 °C (see Figure 12a).…”

Surface-enhanced Raman spectroscopy studies of organophosphorous model molecules and pesticides

“…20 Glyphosate controls weeds by inhibiting the synthesis of aromatic amino acids necessary for protein formation in susceptible plants, and is among the most commonly worldwide used herbicides. 21,22 Fig. 1 shows the molecular structures of the investigated molecules.…”

Electrochemical degradation and mineralization of glyphosate herbicide

“…It took approximately 11 h to degrade glyphosate from 16.9 mg L -1 to 0.7 mg L -1 using a power of UVlamp of 110 W (black light), a wavelength ranging between 310 and 400 nm with a distance between light source and substrate of 32 cm. In spite of the high oxidation rate of glyphosate, longer treatment time and the relatively higher treatment costs hamper the development of photocatalytic processes at large scale applications [18]. Therefore, research has focused on electrochemical oxidation process, which has several advantages such as easy control, no chemical added and highly effective removal of organic and inorganic compounds.…”