Gas phase photocatalytic treatment of trichloroethylene using titanium dioxide irradiated with near ultraviolet light
Abstract
Gas phase photocatalysis using titanium dioxide irradiated with near ultraviolet (UV) light (360nm) was investigated for the application of controlling trichloroethylene (TCE) vapor. Experimental parameters studied were oxygen content, TCE concentration, space time and relative humidity. Photocatalytic degradation of TCE required simultaneous presence of UV light and oxygen. Water vapor severely hindered the photocatalytic TCE degradation efficiency by effectively quenching oxygen atoms, competing with limited adsorption sites, or condensing on photocatalyst surfaces. TCE destruction efficiency increased with decreasing TCE concentration and increasing oxygen content. Viscous and volatile reaction products were observed at relatively low oxygen concentrations but were not detected at near ambient oxygen conditions. The experimental data analysis suggested that TCE oxidation is a dominant process at high oxygen concentration whereas both TCE polymerization and oxidation processes were taking place at low oxygen levels. Mechanistic models based on the formation of activated oxygen atom were proposed to represent TCE decomposition kinetics. A dual site, surface reaction controlled kinetic model was employed to describe the experimental data observed at high oxygen concentrations. Product desorption controlled kinetic model was also proposed for the low oxygen concentration experiments; however, apparent product desorption coefficients obtained revealed that the overall disappearance of TCE was affected by both product desorption and surface reaction mechanisms.
Degree
Ph.D.
Advisors
Marinas, Purdue University.
Subject Area
Civil engineering|Chemistry
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