Herbert E. Allen

Predicting Abiotic Reduction Rate Constants of Munition Compounds in Soils

Paula A. Cárdenas-Hernández, Jimmy Murillo‐Gelvez, Juan C. Rincón-Rodríguez, Dominic M. Di Toro et autres

We report an empirical poly-parameter linear free energy relationship (LFER) for estimating the mass-normalized rate constants for the abiotic reduction of munition compounds (MC) in soil. A total of 131 kinetic experiments were performed, using three classes of MC (nitroaromatic [TNT, DNAN], …

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Synopsis of Discussion Session on the Bioavailability of Inorganic Contaminants

William H. Benson, James J. Alberts, Herbert E. Allen, Carlton D. Hunt et autres

Bioavailability is a widely accepted concept based on the implicit knowledge that before an organism may accumulate or show a biological response to a chemical, that element or compound must be available to the organism. While the concept of bioavailability is widely …

Comparative Evaluation of Mediated Electrochemical Reduction and Chemical Redox Titration for Quantifying the Electron Accepting Capacities of Soils and Redox-Active Soil Constituents

Juan C. Rincón-Rodríguez, Paula A. Cárdenas-Hernández, Jimmy Murillo‐Gelvez, Dominic M. Di Toro et autres

The electron accepting capacity (EAC) of soil plays a pivotal role in the biogeochemical cycling of nutrients and transformation of redox-labile contaminants. Prior EAC studies of soils and soil constituents utilized different methods, reductants, and mediators, making cross-study comparison difficult. This study …

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Linear Free Energy Relationship for Predicting the Rate Constants of Munition Compound Reduction by the Fe(II)–Hematite and Fe(II)–Goethite Redox Couples

Paula A. Cárdenas-Hernández, Kevin P. Hickey, Dominic M. Di Toro, Herbert E. Allen et autres

Abiotic reduction by iron minerals is arguably the most important fate process for munition compounds (MCs) in subsurface environments. No model currently exists that can predict the abiotic reduction rates of structurally diverse MCs by iron (oxyhydr)oxides. We performed batch experiments to …

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Thermodynamic Two-Site Surface Reaction Model for Predicting Munition Constituent Reduction Kinetics with Iron (Oxyhydr)oxides

Kevin P. Hickey, Paula A. Cárdenas-Hernández, Dominic M. Di Toro, Herbert E. Allen et autres

Iron (oxyhydr)oxides comprise a significant portion of the redox-active fraction of soils and are key reductants for remediation of sites contaminated with munition constituents (MCs). Previous studies of MC reduction kinetics with iron oxides have focused on the concentration of sorbed Fe(II) …

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Electron Transfer Energy and Hydrogen Atom Transfer Energy-Based Linear Free Energy Relationships for Predicting the Rate Constants of Munition Constituent Reduction by Hydroquinones

Jimmy Murillo‐Gelvez, Kevin P. Hickey, Dominic M. Di Toro, Herbert E. Allen et autres

No single linear free energy relationship (LFER) exists that can predict reduction rate constants of all munition constituents (MCs). To address this knowledge gap, we measured the reduction rates of MCs and their surrogates including nitroaromatics [NACs; 2,4,6-trinitrotoluene (TNT), 2,4-dinitroanisole (DNAN), 2-amino-4,6-dinitrotoluene …

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Predicting the Rate Constants of Munition Compound Reduction by the Fe(II)-Hematite and Fe(II)-Goethite Redox Couples

Paula A. Cárdenas-Hernández, Kevin P. Hickey, Pei C. Chiu, Dominic Di Toro et autres

Modeling the Reduction Kinetics of Munition Compounds by Humic Acids

Kevin P. Hickey, Jimmy Murillo‐Gelvez, Dominic M. Di Toro, Herbert E. Allen et autres

Dissolved organic matter (DOM) comprises a sizeable portion of the redox-active constituents in the environment and is an important reductant for the abiotic transformation of nitroaromatic compounds and munition constituents (NACs/MCs). Building a predictive kinetic model for these reactions would require the …

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Reductive Transformation of 3-Nitro-1,2,4-triazol-5-one (NTO) by Leonardite Humic Acid and Anthraquinone-2,6-disulfonate (AQDS)

Jimmy Murillo‐Gelvez, Dominic M. Di Toro, Herbert E. Allen, Richard F. Carbonaro et autres

3-Nitro-1,2,4-triazol-5-one (NTO) is a major and the most water-soluble constituent in the insensitive munition formulations IMX-101 and IMX-104. While NTO is known to undergo redox reactions in soils, its reaction with soil humic acid has not been evaluated. We studied NTO reduction …

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Metals in Groundwater

Herbert E. Allen, E. Michael Perdue, David S. Brown

Adsorption to Heterogeneous Surfaces (W.H. van Riemsdijk and T. Hiemstra). Metal Cation/Anion Adsorption on Calcium Carbonate: Implications to Metal Ion Concentrations in Groundwater (J.M. Zachara, C.E. Cowan, and C.T. Resch). Sub-Surface Redox Chemistry: A Comparison of Equilibrium and Reaction-Based Approaches (W. Fish). …

Reduction of 3-Nitro-1,2,4-Triazol-5-One (NTO) by the Hematite–Aqueous Fe(II) Redox Couple

Paula A. Cárdenas-Hernández, Katelyn A. Anderson, Jimmy Murillo‐Gelvez, Dominic M. Di Toro et autres

3-Nitro-1,2,4-triazol-5-one (NTO) is an insensitive munition compound (MC) that has replaced legacy MC. NTO can be highly mobile in soil and groundwater due to its high solubility and anionic nature, yet little is known about the processes that control its environmental fate. …

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A Unified Linear Free Energy Relationship for Abiotic Reduction Rate of Nitroaromatics and Hydroquinones Using Quantum Chemically Estimated Energies

Kevin P. Hickey, Dominic M. Di Toro, Herbert E. Allen, Richard F. Carbonaro et autres

Abstract Determining the fate of nitroaromatic compounds (NACs) in the environment requires the use of predictive models for compounds and conditions for which experimental data are insufficient. Previous studies have developed linear free energy relationships (LFERs) that relate the thermodynamic energy of …

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