Kinetics of carbon tetrachloride reduction at an oxide-free iron electrode

Michelle M. Scherer, John C. Westall, Margaret Ziomek-Moroz, Paul Tratnyek

Research output: Contribution to journalArticle

111 Citations (Scopus)

Abstract

To address some of the fundamental questions regarding the kinetics of reduction of contaminants by zero-valent iron (Fe0), we have taken advantage of the mass transport control afforded by a polished Fe0 rotating disk electrode (RDE) in an electrochemical cell. The kinetics of carbon tetrachloride (CCl4) dechlorination at an Fe0 RDE were studied in pH 8.4 borate buffer at a potential at which an oxide film would not form. In this system, the cathodic current was essentially independent of electrode rotation rate, and the measured first-order heterogeneous rate constant for the chemical reaction (k(ct) = 2.3 x 10-5 cm s-1) was less than the estimated rate constant for mass transfer to the surface. Thus, for the conditions of this study, the rate of reduction of CCl4 by oxide-free Fe0 appears to be dominated by reaction at the metal-water interface rather than by transport to the metal surface. Activation energies for reduction of CCl4 and hexachloroethane by oxide-covered granular Fe0 (measured in batch systems) also indicate that overall rates are limited by reaction kinetics. Since mass transport rates vary little among the chlorinated solvents, it is likely that variation in k(ct) is primarily responsible for the wide range of dechlorination rates that have been reported for batch and column conditions.

Original languageEnglish (US)
Pages (from-to)2385-2391
Number of pages7
JournalEnvironmental Science and Technology
Volume31
Issue number8
DOIs
StatePublished - Aug 1997

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Carbon tetrachloride
Carbon Tetrachloride
Oxides
Dechlorination
electrode
Mass transfer
Iron
Rotating disks
oxide
iron
kinetics
Electrodes
Kinetics
Rate constants
carbon
Metals
Borates
Electrochemical cells
Reaction kinetics
dechlorination

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Environmental Engineering

Cite this

Kinetics of carbon tetrachloride reduction at an oxide-free iron electrode. / Scherer, Michelle M.; Westall, John C.; Ziomek-Moroz, Margaret; Tratnyek, Paul.

In: Environmental Science and Technology, Vol. 31, No. 8, 08.1997, p. 2385-2391.

Research output: Contribution to journalArticle

Scherer, Michelle M. ; Westall, John C. ; Ziomek-Moroz, Margaret ; Tratnyek, Paul. / Kinetics of carbon tetrachloride reduction at an oxide-free iron electrode. In: Environmental Science and Technology. 1997 ; Vol. 31, No. 8. pp. 2385-2391.
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