Pergamon Chtmqhere, Vol. 38, No. 3, pp. 617-627, 1999 Q 1998 Elsevier Science Ltd. All rights reserved W5-6535/99/ $ - see front matter PII: SO0456535(98)00204-S EFFECT OF ADSORBENTS COATED WITH TITANIUM DIOXIDE ON THE PHOTOCATALYTIC DEGRADATION OF PROPOXUR Ming-Chun Lu ‘, Jong-Nan Cheu*, and Kuo-Tai Chang3 1. Department of Environmental Engineering and Heulth Chia Nan College of Pharmacy and Science Tainan, Taiwan 71710, ROC 2. Institute of Environmental Engineering National Chiao Tung University Hsinchu, Taiwan 30039, ROC (Received in Germany 13 February 1998; accepted 15 May 1998) ABSTRACT Photocatalytic oxidation of pesticides in aqueous media irradiated by UV light is a rapidly growing field of research. Therefore, the treatment technology for degradation of propoxur (an insecticide) using titanium dioxide coated on the supports such as activated carbon, zeolite, brick, quartz and glass beads. was performed in this research. Results show that GACiTiOl is the best complexing agent for oxidizing propoxur because of its adsorption properities. The others follow the sequence: plain TiOz > glass beads > zeolite > brick > quartz. The degradation rate of propoxur with plain TiOz is higher than that with TiOz/GAC complexing agent. But the mineralization rate of propoxur with plain TiOz is lower than that with Ti02IGAC complexing agent. However, it can be concluded that using GAC as the support can improve the photocatalytic efficiency 01998 Elsevier Science Ltd. All rights reserved KEY WORDS Photocatalytic oxidation; supported titanium dioxide; propoxur; insecticide INTRODUCTION Most pesticides are non-selective; they are also harmful to ecological systems as well. Therefore. in addition to applying pesticides, the pollution prevention of pesticides used in our environment has to be considered. Photocatalytic oxidation is a promising technology in treating wastewater containing pesticides. Studies have shown that illumination of semiconductor powders in aqueous solutions 617