Kinetics of trichloroethene reduction by zerovalent iron and tin: Pretreatment effect, apparent activation energy, and intermediate products
- National Research Council, Ada, OK (United States)
- Environmental Protection Agency, Ada, OK (United States)
The degradation of trichloroethene (TCE) at 2 mg L{sup {minus}1} in headspace free aqueous solution by zerovalent iron (Fe{sup 0}) and tin (Sn{sup 0}) was studied in batch tests at 10, 25, 40, and 55 C and HCl-treated Fe{sup 0} and Sn{sup 0} at 25 and 55 C. Surface area normalized pseudo-first-order rate constants (k{sub SA}) ranged from 0.44 {times} 10{sup {minus}3} to 4.3 {times} 10{sup {minus}3} h{sup {minus}1} m{sup {minus}2} L for Fisher Fe{sup 0}, 0.029 {times} 10{sup {minus}3} to 0.27 {times} 10{sup {minus}3} h{sup {minus}1} m{sup {minus}2} L for Peerless and Master Builders Fe{sup 0}, and 0.011 {times} 10{sup {minus}3} to 1.31 {times} 10{sup {minus}3} h{sup {minus}1} m{sup {minus}2} L for Fisher and Aldrich Sn{sup 0}. The Aldrich Fe{sup 0} was the least reactive with k{sub SA} values ranging from 0.0016 {times} 10{sup {minus}3} to 0.011 {times} 10{sup {minus}3}j{sup {minus}1} m{sup {minus}2} L. The HCl-washing increased metal surface area and observed rate constant (k) values but generally decreased k{sub SA} values. The calculated apparent activation energy (E{sub a}) using the Arrhenius law for the four temperature levels ranged from 32.2 to 39.4 mol{sup {minus}1} for the untreated Fe{sup 0} metals and 40.5--76.8 kJ mol{sup {minus}1} for the untreated Sn{sup 0} metals. Greater temperature effect was observed for Sn{sup 0} than for Fe{sup 0}. Their results indicate that TCE reduction by Fe{sup 0} and Sn{sup 0} is likely controlled primarily by chemical reaction-limited kinetics rather than by mass transport of the TCE to the metal surface. Both reductive {beta}-elimination reaction and hydrogenolysis reaction are likely involved in the reduction of TCE by both Fe{sup 0} and Sn{sup 0}.
- OSTI ID:
- 298246
- Journal Information:
- Environmental Science and Technology, Vol. 33, Issue 1; Other Information: PBD: 1 Jan 1999
- Country of Publication:
- United States
- Language:
- English
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