| Summary: | 博士 === 國立中興大學 === 環境工程學系所 === 96 === This study investigated the preparation of titanium dioxide/activated carbon composite catalysts, the photocatalytic degradation of dye wastewater, and the relationship between photocatalysts and adsorbents. TiO2 powders were obtained using sol-gel process under the design of the Taguchi’s method. The best candidate for photodegradation is obtained under the condition of the molar ratio of titanium isopropoxide, isopropyl alcohol and acetic acid kept at 1:2:8, calcined at 500℃ for 90 min and then dried after mixing with an adequate amount of activated carbon in water solution for 30 min. X-ray powder diffraction patterns suggest that the grain size of TiO2 is about 20 nm and the crystal structure is mainly in anatase form. The pHZPC of titanium dioxide has been measured to be 6.90. The surface area of composite catalysts is proportional to the ratio of activated carbon synthesized. The synthesis of titanium dioxide and activated carbon is a great benefit to the degradation of dye wastewater and the settleability of catalysts. In the alkaline solution, better photodegradation efficiency of methylene blue is achieved than in the neutral or acidic solution. However, the best photodegradation of Acid Yellow 17 is taken place in the acid solution. As far as the component proportion of photocatalyst is concerned, PT60 (60 wt% TiO2-40 wt% PAC) has the best efficiency, and the photodegradation efficiency decreases with an increase in initial dye concentration. The results also clearly indicate the dye concentration adsorbed on the surface of the composite catalysts during the photocatalytic reaction is lower than the saturated adsorptive concentration in the dark. The kinetic behaviors have been successfully described in a simplified Langmuir-Hinshelwood model.
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