Effects of transition metal and sulfide on the reductive dechlorination of carbon tetrachloride and 1,1,1-trichloroethane by FeS

Choi, Jeong‐Yun; Choi, Kyunghoon; Lee, Woojin

doi:10.1016/j.jhazmat.2008.06.007

Cited by 57 publications

(39 citation statements)

References 30 publications

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“…Elsner and Hofstetter (2011) suggested another abiotic degradation pathway for 1,1,1-TCA via organochlorine radical (by single electron transfer) and/or carbanion with primarily non-chlorinated degradation products and potentially some 1,1-DCA depending on the presence of radical scavengers. This pathway is consistent with observed abiotic degradation of 1,1,1-TCA by FeS in studies by Choi et al (2009) and Gander et al (2002), where 1,1-DCA was found to account for 4-6% of the 1,1,1-TCA degraded.…”

Section: Biotic and Abiotic Degradations Of Tce And 111-tca In The supporting

confidence: 91%

Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

Damgaard

Bjerg

Bælum

et al. 2013

Journal of Contaminant Hydrology

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a b s t r a c tThe degradation of chlorinated ethenes and ethanes in clay till was investigated at a contaminated site (Vadsby, Denmark) by high resolution sampling of intact cores combined with groundwater sampling. Over decades of contamination, bioactive zones with degradation of trichloroethene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA) to 1,2-cis-dichloroethene (cis-DCE) and 1,1-dichloroethane, respectively, had developed in most of the clay till matrix. Dehalobacter dominated over Dehalococcoides (Dhc) in the clay till matrix corresponding with stagnation of sequential dechlorination at cis-DCE. Sporadically distributed bioactive zones with partial degradation to ethene were identified in the clay till matrix (thickness from 0.10 to 0.22 m). In one sub-section profile the presence of Dhc with the vcrA gene supported the occurrence of degradation of cis-DCE and VC, and in another enriched δ 13 C for TCE, cis-DCE and VC documented degradation. Highly enriched δ 13 C for 1,1,1-TCA (25‰) and cis-DCE (−4‰) suggested the occurrence of abiotic degradation in a third sub-section profile. Due to fine scale heterogeneity the identification of active degradation zones in the clay till matrix depended on high resolution subsampling of the clay till cores. The study demonstrates that an integrated approach combining chemical analysis, molecular microbial tools and compound specific isotope analysis (CSIA) was required in order to document biotic and abiotic degradations in the clay till system.

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Section: Biotic and Abiotic Degradations Of Tce And 111-tca In The supporting

confidence: 91%

Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

Damgaard

Bjerg

Bælum

et al. 2013

Journal of Contaminant Hydrology

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“…16 Final concentrations of 1,1-DCA, ethene, ethane and remaining 1,1,1-TCA reflected a mass balance deficit of approximately 48% (i.e., mass amount necessary to maintain the system mass balance expressed as percent of the initial mass). A high deficit was previously observed for 1,1,1-TCA reduction by FeS (79% 55 and ∼94% 14,56 ) or bimetallic reductants (up to ∼20% 16,19 ). The detected but not quantified C 4 , C 5 and C 6 species could explain the unclosed mass balance in our study.…”

Section: ■ Results and Discussionmentioning

confidence: 74%

Carbon and Chlorine Isotope Analysis to Identify Abiotic Degradation Pathways of 1,1,1-Trichloroethane

Palau

Shouakar-Stash

Hunkeler

2014

Environ. Sci. Technol.

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This study investigates dual C−Cl isotope fractionation during 1,1,1-TCA transformation by heat-activated persulfate (PS), hydrolysis/dehydrohalogenation (HY/DH) and Fe(0). Compound-specific chlorine isotope analysis of 1,1,1-TCA was performed for the first time, and transformation-associated isotope fractionation ε bulk C and ε bulk Cl values were −4.0 ± 0.2‰ and no chlorine isotope fractionation with PS, −1.6 ± 0.2‰ and −4.7 ± 0.1‰ for HY/DH, −7.8 ± 0.4‰ and −5.2 ± 0.2‰ with Fe(0). Distinctly different dual isotope slopes (Δδ 13 C/Δδ 37 Cl): ∞ with PS, 0.33 ± 0.04 for HY/DH and 1.5 ± 0.1 with Fe(0) highlight the potential of this approach to identify abiotic degradation pathways of 1,1,1-TCA in the field. The trend observed with PS agreed with a C−H bond oxidation mechanism in the first reaction step. For HY/DH and Fe(0) pathways, different slopes were obtained although both pathways involve cleavage of a C−Cl bond in their initial reaction step. In contrast to the expected larger primary carbon isotope effects relative to chlorine for C−Cl bond cleavage, ε bulk C < ε bulk Cl was observed for HY/DH and in a similar range for reduction by Fe(0), suggesting the contribution of secondary chlorine isotope effects. Therefore, different magnitude of secondary chlorine isotope effects could at least be partly responsible for the distinct slopes between HY/DH and Fe(0) pathways. Following this dual isotope approach, abiotic transformation processes can unambiguously be identified and quantified.

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“…1,1,1-TCA may also be degraded abiotically by dehydrochlorination (a-dehaloelimination) to 1,1-DCE, by hydrolysis to acetate (Scheutz et al, 2011) or by the reaction with reduced Fe, Cr or S (Butler and Hayes 2000;Gander et al, 2002;Elsner et al, 2007;Choi et al, 2009). The pathways to 1,1-DCE and acetate run in parallel and result in $27% of the degradation products as 1,1-DCE (Scheutz et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Stable carbon isotope analysis to distinguish biotic and abiotic degradation of 1,1,1-trichloroethane in groundwater sediments

Broholm

Hunkeler

Tuxen³

et al. 2014

Chemosphere

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Effects of transition metal and sulfide on the reductive dechlorination of carbon tetrachloride and 1,1,1-trichloroethane by FeS

Cited by 57 publications

References 30 publications

Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

Identification of chlorinated solvents degradation zones in clay till by high resolution chemical, microbial and compound specific isotope analysis

Carbon and Chlorine Isotope Analysis to Identify Abiotic Degradation Pathways of 1,1,1-Trichloroethane

Stable carbon isotope analysis to distinguish biotic and abiotic degradation of 1,1,1-trichloroethane in groundwater sediments

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