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Amino Acid-Assisted Dehalogenation of Carbon Tetrachloride by Green Rust: Inhibition of Chloroform Production.

Authors :
Yin W
Strobel BW
B Hansen HC
Source :
Environmental science & technology [Environ Sci Technol] 2017 Mar 21; Vol. 51 (6), pp. 3445-3452. Date of Electronic Publication: 2017 Mar 13.
Publication Year :
2017

Abstract

Layered Fe <superscript>II</superscript> -Fe <superscript>III</superscript> hydroxides (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 (GR <subscript>Cl</subscript> ) 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 Fe <superscript>II</superscript> complexing properties of the amino acids and buffers caused variable extents of GR <subscript>Cl</subscript> dissolution 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.

Details

Language :
English
ISSN :
1520-5851
Volume :
51
Issue :
6
Database :
MEDLINE
Journal :
Environmental science & technology
Publication Type :
Academic Journal
Accession number :
28244752
Full Text :
https://doi.org/10.1021/acs.est.6b06244