Study on the gas-phase photolytic and photocatalytic oxidation of trichloroethylene

Direct sampling mass spectrometer was used to study photolytic and photocatalytic oxidation of trichloroethylene (TCE) in gas-phase. The experiments were conducted under UV lamps with 365 nm (black lamp) and 253.7 nm (germicidal lamp) dominant wavelength, respectively, in the presence or absence of TiO2. Concentrations of TCE and CO2 were detected quantitatively. Mass spectrograph peaks of the documented intermediates and products were detected on-line during the process of photolysis and photocatalysis of TCE. The results indicated that TCE could be directly photodegraded under the irradiation of germicidal lamp, but black lamp could hardly work on TCE by photolysis. This photolytic degradation rate of TCE was much quicker than that of photocatalysis for the same irradiation intensity of germicidal lamp. The products and intermediates detected showed that both photolysis and photocatalysis of TCE were dominated by a free-radical-offence mechanism.