Degradation of NTO induced by superoxide and hydroperoxyl radicals: a comprehensive DFT study

Abstract

Decomposition of environmental pollutant NTO (5-nitro-1,2,4-triazol-3-one) induced by hydroperoxyl radicals in water is a multistep process, which leads to its mineralization.

5-Amino-1,2,4-triazol-3-one Degradation by Indirect Photolysis: A Density Functional Theory Study

“…The predicted products of the multistep process of NTO photolysis were carbon(IV) oxide, carbon(II) oxide, nitrous acid, nitric oxide, hydrazine, ammonia, and nitrogen gas. We also modeled decomposition of NTO induced by reactive oxygen species (ROS) such as the hydroxyl radical, hydroperoxyl radical, superoxide, and singlet oxygen, which are produced in the aqueous solution under sunlight irradiation. − Our results revealed that ROS can cause mineralization of NTO, leading to products of NTO degradation such as nitrous acid, nitric acid, ammonia, nitrogen gas, and carbon(IV) oxide.…”

“…NTO undergoes different biotic and abiotic transformations in the environment. The variety of possible pathways for decomposition of NTO makes its study considerably interesting for experimental and computational chemistry. − NTO undergoes photodegradation upon exposure to UV radiation. The identified aqueous products of NTO phototransformation were nitrite, nitrate, ammonium, and 5-hydroxy-1,2,4-triazol-3-one. , Photolysis represents potentially significant degradation pathway for NTO in the environment, and understanding of the mechanism of photochemical degradation of NTO is necessary in order to predict and control its environmental fate and persistence.…”

“…The experimental reduction potentials of 1.06 and 0.94 eV for HO 2 • and O 2 –• , respectively, show that the hydroperoxyl radical is a slightly stronger oxidant than the superoxide . Both of them take part in decomposition of organic pollutants, such as phenols, dyes, pharmaceuticals, pesticides, etc. ,− Singlet oxygen ( 1 O 2 ), another important ROS with a reduction potential of 0.65 eV, is produced by photosensitizers like dissolved organic matter in the aquatic environment under sunlight irradiation and plays an essential role in decomposition of unsaturated organic compounds that results in the production of peroxides and hydroperoxides. ,− …”

“…To the best of our knowledge, there are no literature data about the possibility of ROS to induce ATO decomposition. Previous works on interaction of ROS with different classes of organic compounds show that the main reaction processes were the attachment to carbon atoms of double bonds, deprotonation, hydrogen atom transfer, and one-electron transfer. ,,− ,− The current study aimed to model ATO degradation induced by superoxide (O 2 –• ), hydroperoxyl radical (HO 2 • ), and singlet oxygen ( 1 O 2 ) in the aqueous solution to evaluate the possibility of ATO mineralization. The novelty of the work is the modeling of the energetically most favorable reactive channel for decomposition of ATO induced by the hydroperoxyl radical and singlet oxygen in the aqueous solution leading to full mineralization of the compound, prediction of products, and the rate-limiting step for the whole process of ATO mineralization.…”