Study of the degradation of an organophosphorus pesticide using electrogenerated hydroxyl radicals or heat-activated persulfate

Abstract

The use of pesticides and their release into the natural environment constitutes a direct threat for the environment and the living beings especially the human health. Consequently, the development of technics to detoxify the pesticide residues to reduce at least areas and contaminated matrix is needed. In the present work, a comparative study was performed on the chemical oxidation of an organophosphorus compound, the dimethoate (DIM), with sulfate radicals and hydroxyl radicals. Both oxidants are generated in situ, the sulfate radicals were produced by heat-activation of persulfate (PS) and hydroxyl radicals were generated by water electrooxidation using a boron doped diamond anode (BDD). For both cases, the target molecule has disappeared but the selective reaction of sulfate radicals with organics led to the production of intermediates which are less biodegradable than DIM since the ratio between the biological oxygen demand (BOD 5) and the chemical oxygen demand (COD) has been divided by 2 within the first hour of the process. Whereas the BOD 5 /COD ratio during the electrochemical oxidation of DIM via hydroxyl radicals showed that it was possible to render the solution biodegradable without reaching a complete mineralization. However, it has been shown that the presence of chlorides in the solution must be avoided because of the formation of undesired organochlorides during the process.

Assessment of Sulfate Radical-Based Advanced Oxidation Processes for Water and Wastewater Treatment: A Review

“…Usually, the higher the temperature, the higher is the radical generation rate and, therefore, the faster is the pollutant's removal [64]. This correlation fits properly to the Arrhenius equation (Equation (8)) [65,66]. Moreover, the contaminant removal rate adjusts in most of the studied cases to pseudo-first order kinetics (Equation (9)) [65][66][67].…”

“…This correlation fits properly to the Arrhenius equation (Equation (8)) [65,66]. Moreover, the contaminant removal rate adjusts in most of the studied cases to pseudo-first order kinetics (Equation (9)) [65][66][67]. However, extremely high temperature does not achieve better micropollutant degradation because those conditions may lead to radical-radical reactions instead of radical-contaminant reactions due to the high radical's concentration [63,64].…”

Degradation of sulfamethoxazole by heat-activated persulfate oxidation: Elucidation of the degradation mechanism and influence of process parameters

“…The influence of various process variables on the degradation of a myriad of organic compounds has been described in some literature sources. For example, some authors [13,14] identified the PS concentration to be a major influential factor, which is positively correlated with the pollutant degradation efficiency. The pH dependence was studied and was attributed to a difference in relative abundancy of the radicals present in the reaction mixture [14,15].…”

Bioremoval of Acephate by biofilm-forming Enterobacter cloacae – VITDAJ8 in a vertical packed bed biofilm bioreactor

“…Discharge of toxic effluents generated from pesticide manufacturing industries into water bodies has become one of the major concerns in environmental safety. Therefore, various physical and chemical treatment methods implemented for the remediation of OP contaminated water include wet oxidation, electrochemical oxidation (Aimer et al, 2017;Aimer et al, 2019), photocatalytic oxidation (Petsas and Vagi, 2018), fumigation (Sintuya et al, 2018), etc.…”