Heterogeneous photocatalytic degradation of trichloroethylene in vapor phase by titanium dioxide

Abstract

This investigation used a packed-bed reactor filled with titanium dioxide catalyst. It was activated by a 365 nm UV light source, for heterogeneous photocatalytic decomposition of trichloroethylene (TCE) under different conditions of flow rate, moisture, and light intensity. At a constant temperature of 30°C, the concentration of 6.5 μM for TCE decreased with increasing time, and reached an equilibrium state in 9 min. For the flow rate of feed gas between 100–900 mL/min, the conversion decreased with an increasing flow rate. The decomposition of TCE at 900 mL/min was only 2.22%, indicating feed gas rapidly passing through the catalyst layer without a reaction. For moisture in the range of 3000-20 000 μL/L, the conversion of TCE decreased with increasing humidity, and the decomposition of this could be inhibited by excessive moisture. The adsorbed water on the catalyst surface could compete with the adsorption of TCE on the sites. By adjusting light intensity in the range of 0.085-0.5 mW/cm 2, the stronger the illumination, the more the conversion of TCE, due to the increased supply of photons for reaction.