Rate-limiting mechanisms for carbon tetrachloride and trichloroethylene reactions at iron surfaces

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Permeable reactive barriers containing zerovalent iron are becoming increasingly popular for in situ remediation of groundwater contaminated with chlorinated organic compounds, e.g., trichloroethylene (TCE). A study was carried out to determine if the rate limiting mechanisms for reductive dechlorination of carbon tetrachloride (CT) and TCE involve electron transfer. The reaction rate of TCE might not be limited by an electron step. The transfer coefficient for CT reduction was independent of temperature, while that for TCE reduction was temperature dependent, indicating that the rate of CT reduction was limited by an electron transfer step, while that for TCE was limited by chemical dependent factors. The apparent activation energy (Ea) for CT reduction decreased with increasingly negative electrode potentials. This suggested that the rate of CT dechlorination was controlled by an electron transfer step. In an outer sphere reaction, a fraction of the polarization energy went towards changing the chemical activation energy. Cathodic polarizations resulted in negative overpotentials, and thus resulted in decreasing Ea values with decreasing electrode potential. In contrast to CT, the weak interdependence of Ea for TCE reduction and E further supported the conclusion that the rate-limiting step for TCE dechlorination does not involve electron transfer.

Original languageEnglish (US)
Title of host publicationACS National Meeting Book of Abstracts
Pages1154-1159
Number of pages6
Volume41
Edition1
StatePublished - 2001
Event221st ACS National Meeting - San Diego, CA, United States
Duration: Apr 1 2001Apr 5 2001

Other

Other221st ACS National Meeting
CountryUnited States
CitySan Diego, CA
Period4/1/014/5/01

Fingerprint

Trichloroethylene
Carbon Tetrachloride
Iron
Dechlorination
Electrons
Activation energy
Cathodic polarization
Electrodes
Remediation
Organic compounds
Reaction rates
Groundwater
Chemical activation
Polarization
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Li, T., & Farrell, J. (2001). Rate-limiting mechanisms for carbon tetrachloride and trichloroethylene reactions at iron surfaces. In ACS National Meeting Book of Abstracts (1 ed., Vol. 41, pp. 1154-1159)

Rate-limiting mechanisms for carbon tetrachloride and trichloroethylene reactions at iron surfaces. / Li, Tie; Farrell, James.

ACS National Meeting Book of Abstracts. Vol. 41 1. ed. 2001. p. 1154-1159.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Li, T & Farrell, J 2001, Rate-limiting mechanisms for carbon tetrachloride and trichloroethylene reactions at iron surfaces. in ACS National Meeting Book of Abstracts. 1 edn, vol. 41, pp. 1154-1159, 221st ACS National Meeting, San Diego, CA, United States, 4/1/01.
Li T, Farrell J. Rate-limiting mechanisms for carbon tetrachloride and trichloroethylene reactions at iron surfaces. In ACS National Meeting Book of Abstracts. 1 ed. Vol. 41. 2001. p. 1154-1159
Li, Tie ; Farrell, James. / Rate-limiting mechanisms for carbon tetrachloride and trichloroethylene reactions at iron surfaces. ACS National Meeting Book of Abstracts. Vol. 41 1. ed. 2001. pp. 1154-1159
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