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Catalytic hydrodechlorination of chlorinated ethenes by nanoscale zero-valent iron

Paper ID Volume ID Publish Year Pages File Format Full-Text
48522 46511 2008 8 PDF Available
Title
Catalytic hydrodechlorination of chlorinated ethenes by nanoscale zero-valent iron
Abstract

The reduction of six chlorinated ethenes by nanoscale iron (<100 nm diameter) synthesized by borohydride reduction was studied in order to determine reaction rates and product distributions and to gain insight into reaction pathways. The transformation of chlorinated ethenes by nanoscale iron proceeded to fully dechlorinated products (ethene and ethane), with no production of chlorinated intermediates, and the reaction rate constants for disappearance of chlorinated ethenes increased with decreasing chlorination (vinyl chloride (VC) > dichloroethenes (DCEs) > trichloroethene (TCE) > tetrachloroethene (PCE)). This trend suggests the reduction of chlorinated ethenes by nanoscale iron did not occur under thermodynamic control (e.g. reduction potential), rather, it proceeded via a catalytic pathway involving reactive hydrogen species. The reduction of TCE under five different conditions of initial dissolved hydrogen concentrations which varied from about 0.02 to 1.2 mM confirmed the importance of hydrogen in the reaction pathway and revealed an excellent linear correlation between rate constant and hydrogen concentration. Reduction of a chlorinated ethane (1,1,1,2-tetrachloroethane) which produced 1,1-DCE as an intermediate, showed no dependence on hydrogen concentrations but the disappearance of the ethene intermediate did. TCE reduction by commercial grade micro-sized iron samples, in contrast, showed insignificant dependence on hydrogen concentration, suggesting the nanoscale iron synthesized by borohydride reduction of iron salts is particularly suited for hydrogen utilization through a catalytic reduction of chlorinated ethenes.

Keywords
Nanoscale iron; Boron; Hydrogen; Catalytic hydrogenation; Reductive dechlorination; Chlorinated compounds
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Catalytic hydrodechlorination of chlorinated ethenes by nanoscale zero-valent iron
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 78, Issues 1–2, 17 January 2008, Pages 53–60
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us