| Perchloroethylene (PCE), a widely used dry cleaning solvent, was treated in the air at room temperature by TiO{dollar}sb2{dollar} photocatalytic oxidation. The PCE destruction efficiency was tested under different conditions which include TiO{dollar}sb2{dollar} weight, retention time, UV light intensity, humidity, and PCE concentration. The TiO{dollar}sb2{dollar} weight, retention time, and UV light intensity have positive effect on the PCE conversion while the humidity and PCE concentration have negative effect. All the experiments were run at conditions that the mass transfer is not controlling. The rate equation was fitted by the Langmuir-Hinshelwood model which, at low PCE concentration, approaches the first order model.; Phosgene, trichloro acetyl chloride (TCAC), and carbon dioxide were detected as the by-products during the TiO{dollar}sb2{dollar} photocatalytic oxidation of PCE in the air. By-product identification at different reaction times indicated that the intermediate TCAC was formed first and then was further oxidized to phosgene and carbon dioxide. When nitrogen gas was used as a substitute for air, only very little amounts of phosgene and carbon tetrachloride were detected. The small quantity of phosgene could be caused by the impurity oxygen in the nitrogen gas cylinder. |
