title: Amino Acid-Assisted Dehalogenation of Carbon Tetrachloride by Green Rust: Inhibition of Chloroform Production.
abstract: Layered FeII-FeIIIhydroxides (green rusts, GRs) are promising reactants for reductive dechlorination of chlorinated solvents due to high reaction rates and the opportunity to inject reactive slurries of the compounds into contaminant plumes. However, it is necessary to develop strategies that reduce the formation of toxic byproducts such as chloroform (CF). In this study, carbon tetrachloride (CT) dehalogenation by the chloride form of GR (GRCl) was tested in the presence of glycine (GLY) and other selected amino acids. GLY, alanine (ALA), and serine (SER) all resulted in remarkable suppression of CF formation with only ∼10% of CF recovery while sarcosine (SAR) showed insignificant effects. For two nonamino acid buffers, TRIS had little effect while HEPES resulted in a 40 times lower rate constant compared to experiments in which no buffer was added. The FeIIcomplexing properties of the amino acids and buffers caused variable extents of GRCldissolution which was linearly correlated with CF suppression and dehalogenation rate. We hypothesize that the CF suppression seen for amino acids is caused by stabilization of carbene intermediates via the carbonyl group. Different effects on CF suppression and CT dehalogenation rate were expected because of the different structural and chemical properties of the amino acids.
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Thorvaldsensvej 40, Frederiksberg C, DK-1871, Denmark.
authors.forename: Weizhao
authors.identifier: 0000-0003-4411-1821
authors.initials: W
authors.lastname: Yin
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Thorvaldsensvej 40, Frederiksberg C, DK-1871, Denmark.
authors.forename: Bjarne W
authors.identifier: 0000-0001-9680-1715
authors.initials: BW
authors.lastname: Strobel
authors.affiliation: Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Thorvaldsensvej 40, Frederiksberg C, DK-1871, Denmark.
authors.forename: Hans Christian
authors.identifier: 0000-0002-8617-2393
authors.initials: HC
authors.lastname: B Hansen
mesh_terms: D000596:Amino Acids; D002251:Carbon Tetrachloride / Q000737:chemistry*; D002725:Chloroform / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction
chemical_list: D000596:Amino Acids; D005290:Ferric Compounds; D002725:Chloroform; D002251:Carbon Tetrachloride