Electrolytic Redox and Electrochemical Generated Alkaline Hydrolysis of Hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) in Sand Columns

Gent, David B.; Wani, Altaf H.; Davis, Jeffrey L.

doi:10.1021/es803567s

Cited by 31 publications

(35 citation statements)

References 24 publications

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“…However, under current intensity of 90 mA, TCE removal rate decreased. This is due to the higher rate of gas (hydrogen and oxygen) bubbles formation which covers the electrode surface [63]. This adversely affects the availability of electrode surface to degrade TCE.…”

Section: Resultsmentioning

confidence: 99%

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Rajić

Fallahpour

2015

Applied Catalysis B: Environmental

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The electrode sequence in a mixed flow-through electrochemical cell is evaluated to improve the hydrodechlorination (HDC) of trichloroethylene (TCE) in aqueous solutions. In a mixed (undivided) electrochemical cell, oxygen generated at the anode competes with the transformation of target contaminants at the cathode. In this study, we evaluate the effect of placing the anode downstream from the cathode and using multiple electrodes to promote TCE reduction. Experiments with a cathode followed by an anode (C→A) and an anode followed by a cathode (A→C) were conducted using mixed metal oxide (MMO) and iron as electrode materials. The TCE removal rates when the anode is placed downstream of the cathode (C→A) were 54% by MMO→MMO, 64% by MMO→Fe and 87% by Fe→MMO sequence. Removal rates when the anode is placed upstream of the cathode (A→C) were 38% by MMO→MMO, 58% by Fe→MMO and 69% by MMO→Fe sequence. Placing the anode downstream of the cathode positively improves (by 26%) the degradation of aqueous TCE in a mixed flow-through cell as it minimizes the influence of oxygen generated at the MMO anode on TCE reduction at the cathode. Furthermore, placing the MMO anode downstream of the cathode neutralizes pH and redox potential of the treated solution. Higher flow velocity under the C→A setup increases TCE mass flux reduction rate. Using multiple cathodes and an iron foam cathode up stream of the anode increase the removal rate by 1.6 and 2.4 times, respectively. More than 99% of TCE was removed in the presence of Pd catalyst on carbon and as an iron foam coating. Enhanced reaction rates found in this study imply that a mixed flow-through electrochemical cell with multiple cathodes up stream of an anode is an effective method to promote the reduction of TCE in groundwater.

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Section: Resultsmentioning

confidence: 99%

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Rajić

Fallahpour

2015

Applied Catalysis B: Environmental

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“…However, when a glacial soil that was more representative of contaminated sites was treated, only 20 % of the 2,4-DNT was transformed and cyclodextrin did not significantly enhance removal rates. In a treatment combining both electrolysis and alkaline hydrolysis, Gent et al [387] created an in situ electrolytic and alkaline hybrid treatment zone in a sand column for treatment of RDX-contaminated water. An upgradient cathode and downgradient anode created alkaline-reducing conditions followed by oxic, acid conditions.…”

Section: Electrochemical Treatment Of Explosivesmentioning

confidence: 99%

Soils contaminated with explosives: Environmental fate and evaluation of state-of-the-art remediation processes (IUPAC Technical Report)

Kalderis

Juhasz

Boopathy

et al. 2011

Pure and Applied Chemistry

156

143

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An explosion occurs when a large amount of energy is suddenly released. This energy may come from an over-pressurized steam boiler, from the products of a chemical reaction involving explosive materials, or from a nuclear reaction that is uncontrolled. In order for an explosion to occur, there must be a local accumulation of energy at the site of the explosion, which is suddenly released. This release of energy can be dissipated as blast waves, propulsion of debris, or by the emission of thermal and ionizing radiation.Modern explosives or energetic materials are nitrogen-containing organic compounds with the potential for self-oxidation to small gaseous molecules (N 2 , H 2 O, and CO 2 ). Explosives are classified as primary or secondary based on their susceptibility of initiation. Primary explosives are highly susceptible to initiation and are often used to ignite secondary explosives, such as TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitroperhydro-1,3,5-triazine), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), and tetryl (N-methyl-N-2,4,6-tetranitroaniline).

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“…The contaminants can be transformed to less toxic byproducts by direct oxidation or reduction on the electrode surface or by indirect biological, chemical or physicochemical transformation in the electrolyte, [1, 2] such as electrochemically-assisted biological reduction, [3] chemical reduction, [4] electrocoagulation, [5] electroflotation [6] and electroflocculation. [7] …”

Section: Introductionmentioning

confidence: 99%

Electrode effects on temporal changes in electrolyte pH and redox potential for water treatment

Ciblak

Mao

Padilla

et al. 2012

Journal of Environmental Science and Health, Part A

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The performance of electrochemical remediation methods could be optimized by controlling the physicochemical conditions of the electrochemical redox system. The effects of anode type (reactive or inert), current density and electrolyte composition on the temporal changes in pH and redox potential of the electrolyte were evaluated in divided and mixed electrolytes. Two types of electrodes were used: iron as a reactive electrode and mixed metal oxide coated titanium (MMO) as an inert electrode. Electric currents of 15, 30, 45 and 60 mA (37.5 mA L−1, 75 mA L−1, 112.5 mA L−1 and 150 mA L−1) were applied. Solutions of NaCl, Na2SO4 and NaHCO3 were selected to mimic different wastewater or groundwater composition. Iron anodes resulted in highly reducing electrolyte conditions compared to inert anodes. Electrolyte pH was dependent on electrode type, electrolyte composition and current density. The pH of mixed-electrolyte was stable when MMO electrodes were used. When iron electrodes were used, the pH of electrolyte with relatively low current density (37.5 mA L−1) did not show significant changes but the pH increased sharply for relatively high current density (150 mA L−1). Sulfate solution showed more basic and relatively more reducing electrolyte condition compared to bicarbonate and chloride solution. The study shows that a highly reducing environment could be achieved using iron anodes in divided or mixed electrolytes and the pH and redox potential could be optimized by using appropriate current and polarity reversal.

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Electrolytic Redox and Electrochemical Generated Alkaline Hydrolysis of Hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) in Sand Columns

Cited by 31 publications

References 24 publications

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution

Soils contaminated with explosives: Environmental fate and evaluation of state-of-the-art remediation processes (IUPAC Technical Report)

Electrode effects on temporal changes in electrolyte pH and redox potential for water treatment

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