Photodegradation of Chlorinated Organic Wastes with n-TiO₂ Promoted by P-CuO

A variety of chlorinated organic wastes were photodecomposed with p-CuO-modified TiO₂ particles (denoted CuO/TiO₂). Based on the photoactivity measured in oxygenated solutions containing sodium 2,2′-dichloropropionate, the photoactivity of TiO₂ is significantly enhanced with p-CuO loading; in the case with 0.4 wt% of CuO, the activity is increased by a facor of 4. Photochemical-TiO₂-slurry cell techniques and voltammetric characterizations suggest this CuO-promoted enhancement is likely to result from the acceleration of oxygen reduction at TiO₂ via Cu^IIO/Cu^IO. Long-term tests showed that these CuO/TiO₂ particles are photochemically robust; within 100-hours' continuous photolysis, insignificant loss in photoactivity was detected. However, increasing loading of p-CuO may jeopardize the photoactivity, due to the deterioration in the TiO₂ absorbability of UV irradiation.