Hydroxyl radical-initiated decomposition of metazachlor herbicide in the gaseous and aqueous phases: Mechanism, kinetics, and toxicity evaluation

New insight into environmental oxidation of phosmet insecticide initiated by HO˙ radicals in gas and water – a theoretical study

“…However, the thermalized HO-adducts are decomposed back to the separated reactants at higher temperatures, and the competition between FHT and RAF processes becomes more signicant than that at low temperatures. This phenomenon was conrmed experimentally 51 and computationally 28,52 in the literature. In addition, P12 is the most favourable HOc-addition site on the phosmet molecule due to its electrophilic character and an unpaired electron in its partially lled d-orbital, making it more attractive to electronrich species such as the HOc radical.…”

“…For this purpose, the ECOSAR method has commonly been employed for toxicity tests on aquatic organisms. 28,59–61…”

“…For this purpose, the ECOSAR method has commonly been employed for toxicity tests on aquatic organisms. 28,[59][60][61] Acute and chronic toxicities applied to three aquatic organisms, including sh, daphnia, and green algae, are employed to estimate the potential aquatic toxicity of phosmet and its transformation products P1, P2, P3, and P4 obtained from the subsequent reactions of the Rad-H31 radical and the two adduct products formed from the OH-addition on the phosphorus P12 atom (i.e., P12-a and P12-b).…”

“…27 Moreover, Dao et al theoretically investigated the oxidation reaction of metazachlor herbicide by HO˙ radicals in the gas and aqueous phases using DFT to evaluate the mechanism and the kinetics of these reactions. 28 Ngo et al performed similar studies on the HO-initiated oxidation of quinmerac herbicide in the aqueous phase at different temperatures and under different pH conditions. 29…”

“…24 Almeida et al shed light on the reaction mechanism of the imine derivative of piperazine oxidation by HOc radicals using theoretically investigated the oxidation reaction of metazachlor herbicide by HOc radicals in the gas and aqueous phases using DFT to evaluate the mechanism and the kinetics of these reactions. 28 Ngo et al performed similar studies on the HO-initiated oxidation of quinmerac herbicide in the aqueous phase at different temperatures and under different pH conditions. 29 Understanding the decomposition and oxidation mechanisms of phosmet insecticides under environmental conditions is crucial for a better assessment of their toxicology and inuence on human health and the environment.…”