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Mixed redox catalytic destruction of chlorinated solvents in soils and groundwater.
- Source :
-
Annals of the New York Academy of Sciences [Ann N Y Acad Sci] 2008 Oct; Vol. 1140, pp. 435-45. - Publication Year :
- 2008
-
Abstract
- A new thermocatalytic method to destroy chlorinated solvents has been developed in the laboratory and tested in a pilot field study. The method employs a conventional Pt/Rh catalyst on a ceramic honeycomb. Reactions proceed at moderate temperatures in the simultaneous presence of oxygen and a reductant (mixed redox conditions) to minimize catalyst deactivation. In the laboratory, stable operation with high conversions (above 90% at residence times shorter than 1 s) for perchloroethylene (PCE) is achieved using hydrogen as the reductant. A molar ratio of H(2)/O(2)= 2 yields maximum conversions; the temperature required to produce maximum conversions is sensitive to influent PCE concentration. When a homologous series of aliphatic alkanes is used to replace hydrogen as the reductant, the resultant mixed redox conditions also produce high PCE conversions. It appears that the dissociation energy of the C-H bond in the respective alkane molecule is a strong determinant of the activation energy, and therefore the reaction rate, for PCE conversion. This new method was employed in a pilot field study in Tucson, Arizona. The mixed redox system was operated semicontinuously for 240 days with no degradation of catalyst performance and complete destruction of PCE and trichloroethylene in a soil vapor extraction gas stream. Use of propane as the reductant significantly reduced operating costs. Mixed redox destruction of chlorinated solvents provides a potentially viable alternative to current soil and groundwater remediation technologies.
- Subjects :
- Alkanes
Biodegradation, Environmental
Catalysis
Chemistry Techniques, Analytical instrumentation
Chemistry Techniques, Analytical methods
Environmental Monitoring methods
Environmental Pollution
Oxygen analysis
Oxygen chemistry
Temperature
Water Pollutants, Chemical metabolism
Chemistry methods
Chlorine analysis
Oxidation-Reduction
Soil Pollutants analysis
Solvents chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1749-6632
- Volume :
- 1140
- Database :
- MEDLINE
- Journal :
- Annals of the New York Academy of Sciences
- Publication Type :
- Academic Journal
- Accession number :
- 18991945
- Full Text :
- https://doi.org/10.1196/annals.1454.044