Direct mass spectrometric studies of the destruction of hazardous wates. 2. Gas-phase photocatalytic oxidation of trichloroethylene over TiO[sub -2]: Products and mechanisms
- National Renewable Energy Lab., Golden, CO (United States)
The gas-phase photocatalytic oxidation of trichloroethylene (TCE) over titanium dioxide was investigated as a potential method for destroying this common pollutant. The results from this study agree with earlier studies in that high levels of destruction of TCE were achieved. Accompanying these high rates of destruction were high quantum yields (approaching unity). However, direct-sampling mass spectrometry and gas-phase Fourier transform infrared (FTIR) spectroscopy revealed that there are significant quantities of byproducts produced [phosgene, dichloroacetyl chloride (DCAC), carbon monoxide, molecular chlorine]. The DCAC has been rationalized on the basis of a chemical reaction mechanism in which the TCE molecules are oxidized in a chain reaction involving Cl atoms. This mechanism appears to be validated by tests with other chlorinated ethylenes (perchloroethylene, dichloroethylenes). Phosgene may arise at least partially from the photocatalytic oxidation of DCAC, and molecular chlorine may result from the recombination of chlorine atoms. The results of this study are discussed relative to aqueous-phase photocatalytic oxidation of TCE where chlorinated intermediates have been observed. 24 refs., 10 figs., 3 tabs.
- OSTI ID:
- 6027862
- Journal Information:
- Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 27:4; ISSN ESTHAG; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400102 -- Chemical & Spectral Procedures
400201 -- Chemical & Physicochemical Properties
400500* -- Photochemistry
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBONIC ACID DERIVATIVES
CATALYSIS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINE
DATA
ELEMENTS
EXPERIMENTAL DATA
HALOGENATED ALIPHATIC HYDROCARBONS
HALOGENS
INFORMATION
LASERS
MASS SPECTROSCOPY
NONMETALS
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHOSGENE
PHOTOCHEMICAL REACTIONS
SPECTROSCOPY
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS