The purpose of this study was to determine the chemical and/or biological factors that cause 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT) and nitrobenzene (NB) to transform to their respective aromatic amines in the Borden aquifer, and to investigate the biodegradation of 2,4-diaminotoluene (2,4-DAT) and 2,6-diaminoluene (2,6-DAT) under aerobic conditions. In situ microcosms (ISM) and laboratory microcosm experiments were used in the investigation. In addition, a sequential treatment system was tested in which columns containing granular iron were followed by either an anaerobic or aerobic soil column. Both 2,4- and 2,6-DNT were used to determine if competitive effects exist between the two. The ISM isolates a volume of the aquifer material and allows for in situ solute loading and sampling in order to characterize chemical or biological reactions. Four ISMs were installed below the water table at CFB Borden. Each ISM was injected with 10 mg/L of either 2,4-DNT, 2,6-DNT, NB, or 2,4-DNT + 2,6-DNT, in two repetitions. In all cases, chloride was also injected as a conservative tracer to monitor for dilution. The results indicated transformation of nitroaromatics via nitro-reduction to their intermediate products, mainly as 2,4-DAT, 2,6-DAT, and aniline. Within 20 days, a loss of up to 92% of 2,4-DNT was observed with the formation of 2,4-DAT. Minor amounts of 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) were also observed. Similarly, up to a 96% loss of 2,6-DNT was seen after 29 days, with degradation products including 2-amino-6-nitrotoluene (2-A-6-NT) and 2,6-DAT. When 2,4- and 2,6-DNT were present in combination, 99% loss of both compounds at similar rates was observed over 20 days following the injections, with degradation products including aminonitrotoluenes and diaminotoluenes. Finally, when nitrobenzene was injected, degradation of up to 99% was observed by day 29, with the formation of aniline as the primary product. To determine the cause of the nitro-reduction, laboratory microcosm experiments were conducted using soil from within the chamber of the ISM’s. Duplicate microcosms were prepared with Borden groundwater and spiked with 2,4- and 2,6-DNT in an anaerobic glovebox. Microcosms were incubated and sampled periodically for approximately 3 months. Several different conditions, including: groundwater and soil, autoclaved groundwater and soil, soil taken at ground surface and groundwater, and autoclaved silica sand and groundwater were created for microcosm experiments to determine whether abiotic or biotic factors caused the reduction of 2,4- and 2,6-DNT. Microcosms which duplicated field conditions in the laboratory had average half-lives of 4.2 days and 5.1 days for 2,4- and 2,6-DNT, respectively, compared to the field result with average half-lives between 3.9 days (2,4-DNT) and 3.5 days (2,6-DNT). Subsequently, a nutrient medium was added to each repetition. The behaviour of DNT degradation did not change significantly, suggesting minimal involvement of biological processes. Furthermore soil analysis showed relatively high concentrations of extractable iron and the presence of magnetite, which are species capable of reducing nitroaromatics. Therefore, it is concluded that nitro-reduction in Borden soil is likely a result of abiotic surface mediated processes. The competitive behaviour of 2,4- and 2,6-DNT was studied in a sequential treatment system which consisted of an anaerobic iron column, followed by either an anaerobic or aerobic soil column. Results showed the same rate of transformation from 2,4- and 2,6-DNT within the iron column, with 100% conversion to 2,4- and 2,6-DAT, respectively. Within the anaerobic and aerobic soil columns, the DATs were highly persistent. When a nutrient solution was added only to the aerobic soil column with DNTs as the initial compounds, results showed a reduction of 2,4-DNT of 17%, with an increase in 2,6-DNT of 22%. The increase in 2,6-DNT may have been a result of differing influent concentrations at earlier pore volumes. When stock solutions in the aerobic column were altered to only include DATs, a reduction of 2,4- and 2,6-DAT was observed at 17% and 18%, respectively. It would appear that an acclimated bacterial community able to transform DNT and DAT was present in the aerobic Borden sand column. Degradation of 2,4- and 2,6-DAT was dependant on the degree of nutrients supplied to indigenous bacterial communities under aerobic conditions.

The purpose of this study was to determine the chemical and/or biological factors that cause 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT) and nitrobenzene (NB) to transform to their respective aromatic amines in the Borden aquifer, and to investigate the biodegradation of 2,4-diaminotoluene (2,4-DAT) and 2,6-diaminoluene (2,6-DAT) under aerobic conditions. In situ microcosms (ISM) and laboratory microcosm experiments were used in the investigation. In addition, a sequential treatment system was tested in which columns containing granular iron were followed by either an anaerobic or aerobic soil column. Both 2,4- and 2,6-DNT were used to determine if competitive effects exist between the two. The ISM isolates a volume of the aquifer material and allows for in situ solute loading and sampling in order to characterize chemical or biological reactions. Four ISMs were installed below the water table at CFB Borden. Each ISM was injected with 10 mg/L of either 2,4-DNT, 2,6-DNT, NB, or 2,4-DNT + 2,6-DNT, in two repetitions. In all cases, chloride was also injected as a conservative tracer to monitor for dilution. The results indicated transformation of nitroaromatics via nitro-reduction to their intermediate products, mainly as 2,4-DAT, 2,6-DAT, and aniline. Within 20 days, a loss of up to 92% of 2,4-DNT was observed with the formation of 2,4-DAT. Minor amounts of 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) were also observed. Similarly, up to a 96% loss of 2,6-DNT was seen after 29 days, with degradation products including 2-amino-6-nitrotoluene (2-A-6-NT) and 2,6-DAT. When 2,4- and 2,6-DNT were present in combination, 99% loss of both compounds at similar rates was observed over 20 days following the injections, with degradation products including aminonitrotoluenes and diaminotoluenes. Finally, when nitrobenzene was injected, degradation of up to 99% was observed by day 29, with the formation of aniline as the primary product. To determine the cause of the nitro-reduction, laboratory microcosm experiments were conducted using soil from within the chamber of the ISM’s. Duplicate microcosms were prepared with Borden groundwater and spiked with 2,4- and 2,6-DNT in an anaerobic glovebox. Microcosms were incubated and sampled periodically for approximately 3 months. Several different conditions, including: groundwater and soil, autoclaved groundwater and soil, soil taken at ground surface and groundwater, and autoclaved silica sand and groundwater were created for microcosm experiments to determine whether abiotic or biotic factors caused the reduction of 2,4- and 2,6-DNT. Microcosms which duplicated field conditions in the laboratory had average half-lives of 4.2 days and 5.1 days for 2,4- and 2,6-DNT, respectively, compared to the field result with average half-lives between 3.9 days (2,4-DNT) and 3.5 days (2,6-DNT). Subsequently, a nutrient medium was added to each repetition. The behaviour of DNT degradation did not change significantly, suggesting minimal involvement of biological processes. Furthermore soil analysis showed relatively high concentrations of extractable iron and the presence of magnetite, which are species capable of reducing nitroaromatics. Therefore, it is concluded that nitro-reduction in Borden soil is likely a result of abiotic surface mediated processes. The competitive behaviour of 2,4- and 2,6-DNT was studied in a sequential treatment system which consisted of an anaerobic iron column, followed by either an anaerobic or aerobic soil column. Results showed the same rate of transformation from 2,4- and 2,6-DNT within the iron column, with 100% conversion to 2,4- and 2,6-DAT, respectively. Within the anaerobic and aerobic soil columns, the DATs were highly persistent. When a nutrient solution was added only to the aerobic soil column with DNTs as the initial compounds, results showed a reduction of 2,4-DNT of 17%, with an increase in 2,6-DNT of 22%. The increase in 2,6-DNT may have been a result of differing influent concentrations at earlier pore volumes. When stock solutions in the aerobic column were altered to only include DATs, a reduction of 2,4- and 2,6-DAT was observed at 17% and 18%, respectively. It would appear that an acclimated bacterial community able to transform DNT and DAT was present in the aerobic Borden sand column. Degradation of 2,4- and 2,6-DAT was dependant on the degree of nutrients supplied to indigenous bacterial communities under aerobic conditions.

Many nitroaromatic compounds (NACs) are considered toxic and potential carcinogens. The purpose of this study was to develop an integrated reductive/oxidative process for treating NAC contaminated waters. The process consists of the combination of zero-valent manganese or iron and a hydroxyl radical based treatment technique. Corrosion promoters were added to the contaminated water to minimize passivation of the metallic species. Water contaminated with 2,4-dinitrotoluen (DNT) was treated with the integrated process using a recirculating batch reactor. It was demonstrated that addition of corrosion promoters to the contaminated water enhanced the rate of reaction of 2,4-DNT with zero-valent iron or manganese. Results showed that iron provided greater reduction of 2,4-DNT than manganese. Chemical oxidation was used to mineralize the reduction products. The degree of mineralization was measured analyzing the samples for total organic carbon and nitrates. A proposed reaction and corrosion mechanisms and rate expressions were developed during the course of the study.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Garamond} This paper presents an approach for modelling a commercial dinitrotoluene (DNT) production process using the CHEMCAD simulation software. A validation of the model was performed based on results of an experimental study carried out at Chematur Engineering AB, Sweden.  Important parameters such as fluid properties, temperature profile and other operating conditions for CHEMCAD steady state model were selected so as to obtain the crude DNT yield as well as the acid –and organic phase compositions within the same range as the reference values from the experimental study. The results showed that the assumption of the steady state model was correct, and that acid –and organic phase compositions were in good agreement, although with a slightly lower sulphuric acid concentration than that observed in the experimental study.  Also, a detailed study was carried out to analyse the effects of physicochemical conditions on the desired product yield. Both the results from the experimental study and the simulated model agree that the effects of mixed acids or heats of mixing acids contribute significantly to the energy balance.  For the appropriateness of the thermodynamics, a NRTL model was chosen and the reactor system was optimized by an equilibrium based approach, producing MNT in 99.8% yield and crude DNT in 99.9% yield. An 80.1/19.9 DNT isomer ratio of the main isomers was achieved and a reduction of by-products in the crude DNT shows a good agreement between the model and the experimental study. / p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Garamond} I denna rapport presenteras en metod för att modellera en kommersiell nitreringsprocess för tillverkning av dinitrotoluen (DNT) med simuleringsprogrammet CHEMCAD. En validering av modellen gjordes baserat på resultat från en experimentell studie utförd hos Chimärer Engineering AB, Sverige.  CHEMCAD-modellen utgår från ”steady-state” drift av anläggningen. Viktiga parametrar såsom fluidegenskaper, temperaturprofil och andra driftsbetingelser i CHEMCAD-modellen valdes för att erhålla ett utbyte av DNT samt sammansättningar av såväl syrafas som organisk fas i god överensstämmelse med referensvärdena från den experimentella studien.  Resultaten visade att antagandena i modellen var korrekta och sammansättningarna för syrafasen och den organiska fasen överensstämde med data från den experimentella studien.  Det genomfördes också en detaljerad studie för att analysera effekterna av fysikalisk-kemiska betingelser på det önskade produktutbytet. Både resultaten från den experimentella studien och data från anläggning i drift överensstämde med den simulerade modellen avseende utspädningsvärmens bidrag till energibalansen.  För att erhålla en lämplig beskrivning av reaktionssystemets termodynamik valdes en NRTL-modell och reaktorsystemet optimerades, vilket gav 99,8 % utbyte av MNT och 99,9 % DNT utbyte. Ett förhållande på 80,1 / 19,9 mellan de två huvudisomererna av DNT uppnåddes och en minskning av biprodukter i DNT produktblandningen. Detta är två exempel på en bra överensstämmelse mellan modellen och experimentstudien.

Wastewater from the manufacture of propellants typically contains 2,4-dinitrotoluene (DNT), a suspected animal carcinogen. Previous studies have indicated that DNT is aerobically biodegradable. However, inconsistent removal of DNT during aerobic treatment has been observed at a munitions wastewater treatment plant, necessitating the use of activated carbon pre-treatment. The objective of this study was to evaluate the effect of nutrient and cosubstrate amendments on the rate and extent of DNT removal. Addition of ethanol (100-500 mg/l) and phosphate (0.8-3.3 mg/l) significantly accelerated the rate of aerobic DNT (0.3-5.6 mg/l) biodegradation. Addition of phosphate alone also increased the rate of DNT degradation, but to a lesser degree. The presence of ethyl ether, another substrate commonly found in munitions plant wastewater, had comparatively little effect on the rate of DNT removal. Interruptions in the DNT manufacturing process can result in DNT being absent from the munitions plant wastewater for extended periods. The effect of such interruptions was evaluated in semi-continuously operated reactors, fed daily with phosphate-amended wastewater, at a hydraulic residence time of 3 days. DNT removal resumed without a lag even after it was absent from the feed for periods up to 15 days. During aerobic biodegradation of DNT, reduction to 4-amino-2-nitrotoluene and 2-amino-4-nitrotoluene was consistently observed, with reduction at the para position predominating. The highest level of aminonitrotoluene formation was 23% of the total DNT degraded. Aminonitrotoluene isomers were consumed shortly after they formed in the semi-continuously operated reactors, confirming the potential for degradation of these metabolites. Although the aminonitrotoluene isomers are not currently regulated, their presence in treated munitions wastewater is a concern due to possible toxicity. / Master of Science

No description available.

Contamination of soils and groundwater with nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT) and dinitrotoluenes (DNTs) has drawn considerable attention due to widely distributed contamination sites and substantial efforts for cleanup. Two isomers of DNT, specifically 2,6-dinitrotoluene (2,6-DNT) and 2,4-dinitrotoluene (2,4-DNT), occur as soil and groundwater contaminants at former TNT production sites. The discovery of bacteria that use DNT isomers as electron donors has encouraged bioremediation at contaminated sites. Current work is extending the existing engineered bioremediation to naturally occurring in situ biodegradation and focuses on the application of natural attenuation (NA) as a remediation strategy for residual DNT at contaminated sites. More specifically this research evaluated factors influencing in situ bioremediation of DNTs and TNT in surface soils, vadose zones, and saturated medium. Applications involving surface soils and vadose zones investigated the potential of water infiltration to promote in situ bioremediation. Studies in saturated media were more applicable to NA. Factors that were also considered in studies conduced included: 1) the presence and distribution of degrading microbes in field soils (Barksdale, WI); 2) the dissolution and bioavailability of contaminants in historically contaminated soils; and 3) the effect of mixtures of contaminants (i.e., DNTs and TNT) on biodegradation processes. This research provided information useful for practitioners considering an in situ bioremediation NA as a remedial solution for contaminated sites. Under the condition simulating downflow of surface waters or rainwater, the rapid rate of DNT degradation could be facilitated by the availability of oxygen in the soil gas without concern of toxicity (i.e., nitrite evolution and pH drop) and addition of nutrients. As a result, in situ bioremediation or NA should be strongly considered as a remedial option for Barksdale soils and similar sites where relatively low concentrations of DNT isomers are present as contaminants. At TNT contaminated sites TNT was not mineralized by indigenous microorganisms despite oxidative biotransformation, and mixed culture capable of growth on DNT also could not develop the mineralization of TNT during DNT degradation. This suggests that the mixtures of contamination did not improve the potential for in situ TNT bioremediation.

Gegenstand der vorliegenden Arbeit war es, die Grundlagen für ein mögliches technisches Verfahren zur Aromatennitrierung mit Salzhydratschmelzen (M(NO3)3 · n H2O, M = Fe, Cr, Bi, In, Al; n = 4 - 9) zu untersuchen. Es sollte geklärt werden, ob Toluol quantitativ zu Dinitrotoluol bzw. Benzol zu Nitrobenzol umgesetzt werden kann. In Screening-Versuchen wurden geeignete, nitrierend wirkende Salzhydrate ermittelt, sowie Wege untersucht, die Reaktivität der eingesetzten Salzhydratschmelzen durch Variation von Wasser- bzw. Säuregehalt, Durchmischung, verschiedenen Schmelzenzusätzen bzw. Reaktionstemperatur zu steigern. Das entstehende Verhältnis der Isomeren der Mono- und Dinitrierung wurde hinsichtlich einer möglichen Beeinflussung untersucht. Das Spektrum an Nebenprodukten wurde bestimmt, sowie Möglichkeiten aufgezeigt, diese zu vermeiden. Dabei konnte gezeigt werden, dass im Gegensatz zum etablierten Mischsäureverfahren beim Einsatz von Salzhydratschmelzen keine kresolischen Nebenprodukte gebildet werden. Weiterhin wurden Möglichkeiten zur Präparation wasserarmer Salzhydratschmelzen durch thermische Entwässerung bzw. Reaktion mit flüssigem N2O4 untersucht, die Löslichkeit der isomeren Zwischen- und Endprodukte in der Salzhydratschmelze bestimmt sowie das thermische Verhalten von Dinitrotoluol in Gegenwart der Salze betrachtet.

The goal of this project was to develop a rapid separation and detection method for analyzing organic compounds in smokeless powders and then test its applicability on gunshot residue (GSR) samples. In this project, a total of 20 common smokeless powder additives and their decomposition products were separated by ultra performance liquid chromatography (UPLC) and confirmed by tandem mass spectrometry (MS/MS) using multiple reaction monitoring mode (MRM). Some of the targeted compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. The compounds were ionized in the MS source using simultaneous positive and negative electrospray ionization (ESI) with negative atmospheric pressure chemical ionization (APCI) in order to detect all compounds in a single analysis. The developed UPLC/MS/MS method was applied to commercially available smokeless powders and gunshot residue samples recovered from the hands of shooters, spent cartridges, and smokeless powder retrieved from unfired cartridges. Distinct compositions were identified for smokeless powders from different manufacturers and from separate manufacturing lots. The procedure also produced specific chemical profiles when tested on gunshot residues from different manufacturers. Overall, this thesis represents the development of a rapid and reproducible procedure capable of simultaneously detecting the widest possible range of components present in organic gunshot residue.

Gegenstand der vorliegenden Arbeit war es, die Grundlagen für ein mögliches technisches Verfahren zur Aromatennitrierung mit Salzhydratschmelzen (M(NO3)3 · n H2O, M = Fe, Cr, Bi, In, Al; n = 4 - 9) zu untersuchen. Es sollte geklärt werden, ob Toluol quantitativ zu Dinitrotoluol bzw. Benzol zu Nitrobenzol umgesetzt werden kann. In Screening-Versuchen wurden geeignete, nitrierend wirkende Salzhydrate ermittelt, sowie Wege untersucht, die Reaktivität der eingesetzten Salzhydratschmelzen durch Variation von Wasser- bzw. Säuregehalt, Durchmischung, verschiedenen Schmelzenzusätzen bzw. Reaktionstemperatur zu steigern. Das entstehende Verhältnis der Isomeren der Mono- und Dinitrierung wurde hinsichtlich einer möglichen Beeinflussung untersucht. Das Spektrum an Nebenprodukten wurde bestimmt, sowie Möglichkeiten aufgezeigt, diese zu vermeiden. Dabei konnte gezeigt werden, dass im Gegensatz zum etablierten Mischsäureverfahren beim Einsatz von Salzhydratschmelzen keine kresolischen Nebenprodukte gebildet werden. Weiterhin wurden Möglichkeiten zur Präparation wasserarmer Salzhydratschmelzen durch thermische Entwässerung bzw. Reaktion mit flüssigem N2O4 untersucht, die Löslichkeit der isomeren Zwischen- und Endprodukte in der Salzhydratschmelze bestimmt sowie das thermische Verhalten von Dinitrotoluol in Gegenwart der Salze betrachtet.