Preparation of La2Ti2O7 by Polymerized Complex Method and Decomposition of Dye in Aqueous Solution by UV/La2Ti2O7 Process

• Main Authors: Wei-Ming Hou, 侯韋銘
• Other Authors: Young Ku
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/5gbk95

碩士 === 國立臺灣科技大學 === 化學工程系 === 95 === Relative to La2Ti2O7 containing perovskite structure prepared by solid state reaction (SSR) method, the sample prepared by polymerized complex (PC) method, one kind of sol-gel method, would exhibit higher surface areas, reduce the crystalline temperature, increase the adsorbed sites and have more uniform morphology. The characterizations of sample were estimated by TG-DTA, XRD, SEM, BET, UV-vis DRS and Zeta potential. The photocatalytic activity of La2Ti2O7 perovskite was examined by decomposing a model pollutant, Relative Red 22 (RR22). The effects of calcined temperature and solution pH were estimated for the photocatalytic activity of La2Ti2O7. The photocatalytic decomposition rate of RR22 by sample prepared by PC method was better than SSR method. In addition to that PC method could provide uniform mixing in molecular level during the preparing process, the sample prepared by PC method had more sensitive to solution pH in surface charge. Because of surface charge of photocatalyst, the reactive mechanism was photocatalysis in acidic solution. However, there were only few pollutants adsorbed on the surface of catalysts in alkaline solution. Hence, the reactive mechanism was photolysis by means of excited hydroxyl radical in the irradiation of UV light. Chromium (Cr) and Ferrum (Fe) ions were incorporated into the lattice of La2Ti2O7 in the process of PC method. Although both Cr-doped and Fe-doped La2Ti2O7 could decrease the band-gap energy from 3.62 eV to 2.23 and 2.87 eV respectively. The Fe-doped La2Ti2O7 had on enhancement in the photooxidization process. However, the incorporation of Cr ions into La2Ti2O7 lattice had almost three times in promotion for decomposing RR22 in the higher wavelength irradiation.