Preparation and photocatalytic activity of nanosized photocatalysts

• Main Author: 謝秉勳
• Other Authors: 林正芳
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/52663749009444329626

碩士 === 國立臺灣大學 === 環境工程學研究所 === 90 === The objective of this study is to increase the phocatalytic activity of semiconductor photocatalysts. Nanosized titanium dioxide powder was synthesized via the sol-gel procedure and modified the via coupled photocatalysts. The photocatalysed degradation of 4-chlorophenol (4-CP) in water was comparatively examined with these photocatalysts. The microstructural and chemical properties of titanium dioxide and coupled cadium selenide/titanium dioxide were investigated. The specific surface area of TiO2 was gradual decreased from 158.5 to 23.45 m2/g after calcinations at 500℃. XRD analysis showed that the samples were a mixture of anatase and rutile phase. The size is changed from 15 to 30 nm. From XPS measurement, the valency state of Ti element in TiO2 was Ti(Ⅳ). For CdSe/TiO2 samples, the specific surface area was 7.047 m2/g and the deposition proportion of CdSe was about 27.6%. In the results of photocalysis, higher photodegradation efficiency of 4-CP was observed at higher pH values. In UV254 nm system, the degradation efficiency of 4-CP and TOC with TiO2(SG) powder was higher than commercial TiO2(R-dH) powder, but the effect was not apparent in 365nm system. For the coupled semiconductor system, the apparent first-order rate constants with CdSe/TiO2 powder was obtained to be about 98% and 273% larger than with TiO2(R-dH) powder under the condition of pH=7 and pH=11 in UV254 nm. In UV365 nm system, a 9% increase in rate constant in coupled semiconductor system relative to the single semiconductor system.