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Sviatenko LK, Gorb L, Leszczynski J. Degradation of NTO induced by superoxide and hydroperoxyl radicals: a comprehensive DFT study. Phys Chem Chem Phys 2023; 26:493-503. [PMID: 38084040 DOI: 10.1039/d3cp05603a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Reactive oxygen species, produced in the aquatic environment under sunlight irradiation, actively take part in degradation of environmental pollutants. NTO (5-nitro-1,2,4-triazol-3-one), being a primary ingredient in a suite of insensitive munitions formulations, may be released into training range soils after incomplete detonations and dissolved in surface water and groundwater due to good water solubility. A detailed investigation of a possible mechanism for NTO decomposition in water induced by superoxide and hydroperoxyl radicals as one of the pathways for NTO environmental degradation was performed with a computational study at the PCM(Pauling)/M06-2X/6-311++G(d,p) level. Superoxide causes rapid deprotonation of NTO. Decomposition of NTO induced by hydroperoxyl radicals was found to be a multistep process leading to mineralization of the nitrocompound. The reaction process may begin with hydroperoxyl radical attachment to carbon atom of the CN double bond of NTO, then proceeds through rupture of C-N bonds and addition of water molecules leading to the formation of nitrous acid, ammonia, nitrogen gas, hydrazine, and carbon(IV) oxide. The obtained results indicate that the anionic form of NTO shows a higher reactivity towards hydroperoxyl radicals than its neutral form. Excitation of NTO by sunlight enables complete mineralization of NTO induced by superoxide. The calculated activation energies and exergonicity of the studied processes support the contribution of hydroperoxyl radicals and superoxide to the degradation of NTO in the environment into low-weight inorganic compounds.
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Affiliation(s)
- Liudmyla K Sviatenko
- Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Physics & Atmospheric Sciences, Jackson State University, Jackson, Mississippi, 39217, USA.
| | - Leonid Gorb
- Institute of Molecular Biology and Genetics, NAS of Ukraine, 150 Zabolotny Str., Kyiv, 03143, Ukraine
- QSAR Lab Sp. z o.o. Trzy Lipy 3, B, Gdansk, 80-172, Poland
| | - Jerzy Leszczynski
- Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Physics & Atmospheric Sciences, Jackson State University, Jackson, Mississippi, 39217, USA.
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Sviatenko LK, Gorb L, Leszczynski J. Role of Hydroxyl Radical in Degradation of NTO: DFT Study. J Phys Chem A 2023; 127:8584-8594. [PMID: 37796737 DOI: 10.1021/acs.jpca.3c04981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Hydroxyl radicals are important reactive oxygen species produced in the aquatic environment under sunlight irradiation. Many organic pollutants may be decomposed as they encounter hydroxyl radicals, due to their high oxidative ability. NTO (5-nitro-1,2,4-triazol-3-one), an energetic material used in military applications, may be released to the environment and dissolved in surface water and groundwater due to its good water solubility. A detailed investigation of the possible mechanism for NTO decomposition in water induced by hydroxyl radical as one of the pathways for NTO environmental degradation was performed by computational study at the PCM/M06-2X/6-311++G(d,p) level. Decomposition of NTO was found to be a multistep process that may begin with an addition of hydroxyl radical to the carbon atom of C═N double bond and consequent release of a nitrite radical. The formed intermediate undergoes a series of chemical transformations that include the attachments of hydroxyl radical to carbon atoms, the transfer of hydrogen to hydroxyl radical, isomerization, and bond cleavage, leading to low-weight inorganic compounds, such as ammonia, nitrogen gas, nitrous acid, nitric acid, and carbon(IV) oxide. The anionic form of NTO is more reactive toward interaction with the hydroxyl radical as compared with its neutral form. Calculated activation energies and high exergonicity of the studied process support the significant contribution of the hydroxyl radical to NTO mineralization in environment.
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Affiliation(s)
- Liudmyla K Sviatenko
- Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Physics & Atmospheric Sciences, Jackson State University, Jackson, Mississippi 39217, United States
| | - Leonid Gorb
- Institute of Molecular Biology and Genetics, NAS of Ukraine, 150 Zabolotny Str., Kyiv 03143, Ukraine
- QSAR Lab Sp. z o.o., Trzy Lipy 3, B, Gdansk 80-172, Poland
| | - Jerzy Leszczynski
- Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Physics & Atmospheric Sciences, Jackson State University, Jackson, Mississippi 39217, United States
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Milstead RP, Berg SM, Kelly BM, Knellwolf CD, Larson CJ, Wammer KH, Remucal CK. Limitations of conventional approaches to identify photochemically produced reactive intermediates involved in contaminant indirect photodegradation. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1694-1707. [PMID: 37728410 PMCID: PMC10591881 DOI: 10.1039/d3em00304c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Dissolved organic matter (DOM) mediated indirect photodegradation can play an important role in the degradation of aquatic contaminants. Predicting the rate of this process requires knowledge of the photochemically produced reactive intermediates (PPRI) that react with the compound of interest, as well as the ability of individual DOM samples to produce PPRI. Key PPRI are typically identified using quencher studies, yet this approach often leads to results that are difficult to interpret. In this work, we analyze the indirect photodegradation of atorvastatin, carbamazepine, sulfadiazine, and benzotriazole using a diverse set of 48 waters from natural and engineered aquatic systems. We use this large data set to evaluate relationships between PPRI formation and indirect photodegradation rate constants, which are directly compared to results using standard quenching experiments. These data demonstrate that triplet state DOM (3DOM) and singlet oxygen (1O2) are critical PPRI for atorvastatin, carbamazepine, and sulfadiazine, while hydroxyl radical (˙OH) contributes to the indirect photodegradation of benzotriazole. We caution against relying on quenching studies because quenching of 3DOM limits the formation of 1O2 and all studied quenchers react with ˙OH. Furthermore, we show that DOM composition directly influences indirect photodegradation and that low molecular weight, microbial-like DOM is positively correlated with the indirect photodegradation rates of carbamazepine, sulfadiazine, and benzotriazole.
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Affiliation(s)
- Reid P Milstead
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, Wisconsin 53706, USA.
| | - Stephanie M Berg
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, Wisconsin 53706, USA.
| | - Bella M Kelly
- Department of Chemistry, University of St. Thomas, St. Paul, Minnesota 55105, USA
| | | | - Cooper J Larson
- Department of Chemistry, University of St. Thomas, St. Paul, Minnesota 55105, USA
| | - Kristine H Wammer
- Department of Chemistry, University of St. Thomas, St. Paul, Minnesota 55105, USA
| | - Christina K Remucal
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 N. Park St., Madison, Wisconsin 53706, USA.
- Department of Civil and Environmental Engineering, University of Wisconsin - Madison, Madison, Wisconsin 53706, USA
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