GC-FID Determination of Chlorobenzene Isomers in Methanogenic Batch-Cultures from River Sediments

Stan, Hans‐Jürgen; Kirsch, Nils

doi:10.1080/03067319508027225

Cited by 11 publications

(6 citation statements)

References 7 publications

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“…The chlorinated hydrocarbons represent an important class of environmental pollutant. − The carbon backbones adopted are identical to those observed in the pyrolysis/combustion of hydrocarbons, and like their nonchlorinated counterparts, chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) tend to form abundantly in pyrolysis and combustion systems. Probable carcinogens, control, and mitigation of the formation of these compounds is of obvious importance, which therefore demands detailed knowledge of the formation of these compounds.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Studies into the Formation of C₄–C₆ Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

McIntosh

Russell

2014

J. Phys. Chem. A

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This work presents a study of the pyrolytic formation of vinylacetylene and benzene congeners formed from chlorinated hydrocarbon precursors, a complex, multipath polymerization system formed in a monomer-rich environment. (Co-)pyrolyses of dichloro- and trichloroethylene yield a rich array of products, and assuming a single dominant underlying growth mechanism, this (on comparing expected and observed products) allows a number of potentially competing channels to C4 and C6 products to be ruled out. Poor congener/isomer descriptions rule out even-carbon radical routes, and the absence of C3 and C5 products rule out odd-carbon processes. Vinylidenes appear unable to describe the increased reactivity of acetylenes with chlorination noted in our experiments, leaving molecular acetylene dimerization processes and, in C6 systems, the closely related Diels-Alder cyclization as the likely reaction mechanism. The feasibility of these routes is further supported by ab initio calculations. However, some of the most persuasive evidence is provided by congener-specific yield predictions enabled by the construction of a probability tree analogue of kinetic modeling. This approach is relatively quick to construct, provides surprisingly accurate predictions, and may be a very useful tool in screening for important reaction channels in poorly understood congener- or isomer-rich reaction systems.

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Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Studies into the Formation of C₄–C₆ Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

McIntosh

Russell

2014

J. Phys. Chem. A

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“…Chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) are a class of environmental toxins that have been identified in a number of environmental and biological samples; − of these, polychlorinated naphthalenes (PCNs) and styrenes have also been of particular interest given their toxicity and persistence. − ,− Studies into the growth of these compounds at high temperatures are necessary for the development of strategies to mitigate their formation. Additionally, PCNs represent the smallest Cl-PAHs, and as such the mechanism of their formation will likely represent prototype reactions for larger PAHs.…”

Section: Introductionmentioning

confidence: 99%

Role of Hydrogen Abstraction Acetylene Addition Mechanisms in the Formation of Chlorinated Naphthalenes. 2. Kinetic Modeling and the Detailed Mechanism of Ring Closure

McIntosh

Russell

2014

J. Phys. Chem. A

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The dominant formation mechanisms of chlorinated phenylacetylenes, naphthalenes, and phenylvinylacetylenes in relatively low pressure and temperature (∼40 Torr and 1000 K) pyrolysis systems are explored. Mechanism elucidation is achieved through a combination of theoretical and experimental techniques, the former employing a novel simplification of kinetic modeling which utilizes rate constants in a probabilistic framework. Contemporary formation schemes of the compounds of interest generally require successive additions of acetylene to phenyl radicals. As such, infrared laser powered homogeneous pyrolyses of dichloro- or trichloroethylene were perturbed with 1,2,4- or 1,2,3-trichlorobenzene. The resulting changes in product identities were compared with the major products expected from conventional pathways, aided by the results of our previous computational work. This analysis suggests that a Bittner-Howard growth mechanism, with a novel amendment to the conventional scheme made just prior to ring closure, describes the major products well. Expected products from a number of other potentially operative channels are shown to be incongruent with experiment, further supporting the role of Bittner-Howard channels as the unique pathway to naphthalene growth. A simple quantitative analysis which performs very well is achieved by considering the reaction scheme as a probability tree, with relative rate constants being cast as branching probabilities. This analysis describes all chlorinated phenylacetylene, naphthalene, and phenylvinylacetylene congeners. The scheme is then tested in a more general system, i.e., not enforcing a hydrogen abstraction/acetylene addition mechanism, by pyrolyzing mixtures of di- and trichloroethylene without the addition of an aromatic precursor. The model indicates that these mechanisms are still likely to be operative.

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“…Chlorobenzene concentrations were determined by removing 1-ml aliquots of bacterial suspension from a culture bottle with a glass syringe, followed by extraction with 1 ml of hexane. Analysis of the extracts was done by gas chromatography (GC)-flame ionization detection with 2,4-dichlorotoluene as an internal standard (44). Dechlorination was expressed as the percentage of dichlorobenzenes formed relative to the sum of all chlorobenzenes within a culture vessel.…”

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confidence: 99%

Physiological Characterization of a Bacterial Consortium Reductively Dechlorinating 1,2,3- and 1,2,4-Trichlorobenzene

Adrian

Manz

Szewzyk

et al. 1998

Appl Environ Microbiol

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A bacterial mixed culture reductively dechlorinating trichlorobenzenes was established in a defined, synthetic mineral medium without any complex additions and with pyruvate as the carbon and energy source. The culture was maintained over 39 consecutive transfers of small inocula into fresh media, enriching the dechlorinating activity. In situ probing with fluorescence-labeled rRNA-targeted oligonucleotide probes revealed that two major subpopulations within the microbial consortium were phylogenetically affiliated with a sublineage within the Desulfovibrionaceaeand the gamma subclass of Proteobacteria. The bacterial consortium grew by fermentation of pyruvate, forming acetate, propionate, CO2, formate, and hydrogen. Acetate and propionate supported neither the reduction of trichlorobenzenes nor the reduction of sulfate when sulfate was present. Hydrogen and formate were used for sulfate reduction to sulfide. Sulfate strongly inhibited the reductive dechlorination of trichlorobenzenes. However, when sulfate was depleted in the medium due to sulfate reduction, dechlorination of trichlorobenzenes started. Similar results were obtained when sulfite was present in the cultures. Molybdate at a concentration of 1 mM strongly inhibited the dechlorination of trichlorobenzenes. Cultures supplied with molybdate plus sulfate did not reduce sulfate, but dechlorination of trichlorobenzenes occurred. Supplementation of electron-depleted cultures with various electron sources demonstrated that formate was used as a direct electron donor for reductive dechlorination, whereas hydrogen was not.

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GC-FID Determination of Chlorobenzene Isomers in Methanogenic Batch-Cultures from River Sediments

Cited by 11 publications

References 7 publications

Experimental and Theoretical Studies into the Formation of C₄–C₆ Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

Experimental and Theoretical Studies into the Formation of C₄–C₆ Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

Role of Hydrogen Abstraction Acetylene Addition Mechanisms in the Formation of Chlorinated Naphthalenes. 2. Kinetic Modeling and the Detailed Mechanism of Ring Closure

Physiological Characterization of a Bacterial Consortium Reductively Dechlorinating 1,2,3- and 1,2,4-Trichlorobenzene

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GC-FID Determination of Chlorobenzene Isomers in Methanogenic Batch-Cultures from River Sediments

Cited by 11 publications

References 7 publications

Experimental and Theoretical Studies into the Formation of C4–C6 Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

Experimental and Theoretical Studies into the Formation of C4–C6 Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

Role of Hydrogen Abstraction Acetylene Addition Mechanisms in the Formation of Chlorinated Naphthalenes. 2. Kinetic Modeling and the Detailed Mechanism of Ring Closure

Physiological Characterization of a Bacterial Consortium Reductively Dechlorinating 1,2,3- and 1,2,4-Trichlorobenzene

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Experimental and Theoretical Studies into the Formation of C₄–C₆ Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions

Experimental and Theoretical Studies into the Formation of C₄–C₆ Products in Partially Chlorinated Hydrocarbon Pyrolysis Systems: A Probabilistic Approach to Congener-Specific Yield Predictions