Surface-promoted hydrolysis of 2,4,6-trinitrotoluene and 2,4-dinitroanisole on pyrogenic carbonaceous matter

Ding, Kai; Byrnes, Cory; Bridge, Jarrod; Grannas, A. M.; Wang, Xu

doi:10.1016/j.chemosphere.2018.01.038

Cited by 15 publications

(10 citation statements)

References 32 publications

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“…Thermally altered plant biomass (char) is ubiquitous in the environment and has long been recognized as an important geosorbent for organic compounds and inorganic species, including pollutants. − More recent work has revealed that chars are also redox-active by accepting and donating electrons and, thereby, participate in biogeochemical electron transfer processes and pollutant redox transformations. − Chars accept electrons from anaerobic microbial respiration or from inorganic reductants in the environment (e.g., hydrogen sulfide). ,,,,− ,,,, Following reduction, chars may then transfer electrons to both organic and inorganic pollutants, thereby facilitating their reductive transformation. ,,− ,,,, Chars are also involved in electron transfer between microbial cells , or from metal-reducing bacteria to hematite or ferrihydrite. , In addition, electron transfer to and from chars was shown to mitigate emissions of the radiatively active trace gas N 2 O from agricultural soils. , The important role of chars in redox reactions has led to considerable interest in characterizing the redox chemistry and reactivity of chars. However, chars also release dissolved organic carbon (DOC), which herein we refer to as pyrogenic dissolved organic matter (pyDOM) (operationally defined as DOC from bulk chars that passes through 0.45 μm filters). − The released amounts of pyDOM are considered significant in the global carbon cycle: for instance, pyDOM is estimated to contribute ∼10% of the riverine flux of DOC to the oceans. , Yet, compared to bulk chars and non-pyrogenic DOM, only a few studies have characterized ...…”

Section: Introductionmentioning

confidence: 99%

Redox Properties of Pyrogenic Dissolved Organic Matter (pyDOM) from Biomass-Derived Chars

Wang

Walpen

Keiluweit

et al. 2021

Environ. Sci. Technol.

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Chars are ubiquitous in the environment and release significant amounts of redox-active pyrogenic dissolved organic matter (pyDOM). Yet, the redox properties of pyDOM remain poorly characterized. This work provides a systematic assessment of the quantity and redox properties of pyDOM released at circumneutral pH from a total of 14 chars pyrolyzed from wood and grass feedstocks from 200 to 700 °C. The amount of released pyDOM decreased with increasing pyrolysis temperature of chars, reflecting the increasing degree of condensation and decreasing char polarity. Using flow-injection analysis coupled to electrochemical detection, we demonstrated that electron-donating capacities (EDC pyDOM ; up to 6.5 mmol e− •g C −1 ) were higher than electron-accepting capacities (EAC pyDOM ; up to 1.2 mmol e− •g C −1 ) for all pyDOM specimens. The optical properties and low metal contents of the pyDOM implicate phenols and quinones as the major redox-active moieties. Oxidation of a selected pyDOM by the oxidative enzyme laccase resulted in a 1.57 mmol e− •g C −1 decrease in EDC pyDOM and a 0.25 mmol e− •g C −1 increase in EAC pyDOM , demonstrating a largely irreversible oxidation of presumably phenolic moieties. Non-mediated electrochemical reduction of the same pyDOM resulted in a 0.17 mmol e− •g C −1 increase in EDC pyDOM and a 0.24 mmol e− •g C −1 decrease in EAC pyDOM , consistent with the largely reversible reduction of quinone moieties. Our results imply that pyDOM is an important dissolved redox-active phase in the environment and requires consideration in assessing and modeling biogeochemical redox processes and pollutant redox transformations, particularly in char-rich environments.

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Section: Introductionmentioning

confidence: 99%

Redox Properties of Pyrogenic Dissolved Organic Matter (pyDOM) from Biomass-Derived Chars

Wang

Walpen

Keiluweit

et al. 2021

Environ. Sci. Technol.

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“…The Langmuir kinetic model was also used to fit our adsorption kinetic data for comparison purposes following the method described in our previous publications. , Briefly, the mass transfer of TCNM from solution to the solid phase can be described by eqs and , where q is the solid-phase concentration of TCNM (mg/g), k a is the rate constant (L mg –1 h –1 ) associated with the solution-to-solid mass transfer (i.e., sorption) of TCNM, C is the aqueous concentration (mg L –1 ), Q is the total number of sorption sites (mg g –1 ), and k d is the rate constant (h –1 ) associated with the solid-to-solution mass transfer (i.e., desorption) of TCNM. The adsorption capacities ( Q ) of CMP-1-700, CMP-1-800, and CMP-1-900 were determined experimentally by increasing the TCNM concentrations in methanol.…”

Section: Resultsmentioning

confidence: 99%

“…As shown in eq , the decay of TCNM in the batch reactors containing CMPs was the sum of several competing processes based on the Langmuir kinetic model: , (1) the adsorption ( k a ) of TCNM from the aqueous phase to the surface of CMPs, (2) the desorption ( k d ) of TCNM from the surface of CMPs back to the aqueous solution, and (3) the surface reaction ( k rxn ) between adsorbed TCNM and CMPs where Q – q represents the concentration of the vacant sorption sites, k rxn is the surface rate constant (h –1 ), and all other parameters were defined in the previous section.…”

Section: Resultsmentioning

confidence: 99%

“…Surface Reaction Rates of the TCNM Decay. As shown in eq 10, the decay of TCNM in the batch reactors containing CMPs was the sum of several competing processes based on the Langmuir kinetic model: 10,49 (1) the adsorption (k a ) of TCNM from the aqueous phase to the surface of CMPs, (2) the desorption (k d ) of TCNM from the surface of CMPs back to the aqueous solution, and (3) the surface reaction (k rxn ) between adsorbed TCNM and CMPs…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Probing the Surface Reactivity of Pyrogenic Carbonaceous Material (PCM) through Synthesis of PCM-Like Conjugated Microporous Polymers

Zhao

Mao

Chu

et al. 2019

Environ. Sci. Technol.

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Pyrogenic carbonaceous matter (PCM) is redox-active and promotes both abiotic and biotic reactions in the environment, possibly as a result of its conductivity and phenolic/quinone functional groups. However, due to the complexity of PCM, the contribution of conductivity or phenolic/quinone functional groups to its redox activity is poorly understood, which hinders its potential engineering applications. Here, we synthesized tunable conjugated microporous polymers (CMPs) that possess key properties of PCM, which can be used as PCM analogues to provide insights to PCM reactivity. Specifically, controlled incorporation of phenolic moieties into CMPs during polymer synthesis affected electron-donating capacity, while carbonization of CMPs at various temperatures altered conductivity. Both properties were then correlated with PCM reactivity measured by the decay kinetics of a model pollutant trichloronitromethane. We demonstrate that some of the prepared CMPs enabled transformation of trichloronitromethane, while no decay was observed in the absence of CMPs. Results of further investigation suggest that trichloronitromethane decay occurs by reductive dechlorination, suggesting that CMPs are electron donors and the first dissociative electron transfer from CMPs was likely to be the rate-limiting step. Conductivity but not electron-donating capacity was positively correlated with CMP-mediated trichloronitromethane decay kinetics, suggesting an important role of the electron transfer kinetics at the interface for PCM-mediated transformation of environmental pollutants.

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“…The degradation of nitroaromatic compounds like TNT and DNAN by hydrolysis may occur by a variety of thermodynamically favorable reaction pathways initiated by OH – . , Hydrolysis reactions include Meisenheimer complex formation, nucleophilic aromatic substitution, and proton abstraction. These reactions can take place in sequence, which will result in a large reaction network consisting of these interconnected and overlapping reaction pathways. , In addition, in the environment, the reaction network is an open system because it exchanges material with the outside environment.…”

Section: Introductionmentioning

confidence: 99%

Computational Predictions of the Hydrolysis of 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)

et al. 2022

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Hydrolysis is a common transformation reaction that can affect the environmental fate of many organic compounds. In this study, three proposed mechanisms of alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) and 2,4dinitroaniline (DNAN) were investigated with plane-wave density functional theory (DFT) combined with ab initio and classical molecular dynamics (AIMD/ MM) free energy simulations, Gaussian basis set DFT calculations, and correlated molecular orbital theory calculations. Most of the computations in this study were carried out using the Arrows web-based tools. For each mechanism, Meisenheimer complex formation, nucleophilic aromatic substitution, and proton abstraction reaction energies and activation barriers were calculated for the reaction at each relevant site. For TNT, it was found that the most kinetically favorable first hydrolysis steps involve Meisenheimer complex formation by attachment of OH − at the C1 and C3 arene carbons and proton abstraction from the methyl group. The nucleophilic aromatic substitution reactions at the C2 and C4 arene carbons were found to be thermodynamically favorable. However, the calculated activation barriers were slightly lower than in previous studies, but still found to be ΔG ‡ ≈ 18 kcal/mol using PBE0 AIMD/MM free energy simulations, suggesting that the reactions are not kinetically significant. For DNAN, the barriers of nucleophilic aromatic substitution were even greater (ΔG ‡ > 29 kcal/mol PBE0 AIMD/MM). The most favorable hydrolysis reaction for DNAN was found to be a two-step process in which the hydroxyl first attacks the C1 carbon to form a Meisenheimer complex at the C1 arene carbon C1−(OCH 3 )OH − , and subsequently, the methoxy anion (−OCH 3 ) at the C1 arene carbon dissociates and the proton shuttles from the C1−OH to the dissociated methoxy group, resulting in methanol and an aryloxy anion.

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Surface-promoted hydrolysis of 2,4,6-trinitrotoluene and 2,4-dinitroanisole on pyrogenic carbonaceous matter

Cited by 15 publications

References 32 publications

Redox Properties of Pyrogenic Dissolved Organic Matter (pyDOM) from Biomass-Derived Chars

Redox Properties of Pyrogenic Dissolved Organic Matter (pyDOM) from Biomass-Derived Chars

Probing the Surface Reactivity of Pyrogenic Carbonaceous Material (PCM) through Synthesis of PCM-Like Conjugated Microporous Polymers

Computational Predictions of the Hydrolysis of 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)

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