HETEROGENEOUS PHOTOCATALYTIC DEGRADATION OF TRICHLOROETHYLENE IN VAPOR-PHASE BY TITANIUM-DIOXIDE

This investigation used a packed-bed reactor filled with titanium diox ide catalyst. It was activated by a 365 nm UV light source, for hetero geneous photocatalytic decomposition of trichloroethylene (TCE) under different conditions of flow rate, moisture, and light intensity. At a constant temperature of 30 degrees C, the concentration of 6.5 mu M f or TCE decreased with increasing time, and reached an equilibrium stat e in 9 min. For the flow rate of feed gas between 100-900 mL/min, the conversion decreased with an increasing now 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 ra nge of 3000-20 000 mu L/L, the conversion of TCE decreased with increa sing humidity, and the decomposition of this could be inhibited by exc essive moisture. The adsorbed water on the catalyst surface could comp ete with the adsorption of TCE on the sites. By adjusting light intens ity 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 photon s for reaction. (C)1998 Elsevier Science Ltd.