| Summary: | 博士 === 靜宜大學 === 應用化學系 === 102 === Part I、The photocatalytic degradation of terbufos and disulfoton in aqueous suspensions were investigated by using titanium dioxide (TiO2) and polyoxometalates (POM) as photocatalysts. About 99 % of organo -phosphorus pesticides were degraded by using TiO2 and POM after UV irradiation for 90 min and 300 min, respectively. Factors such as pH of the system, photocatalysts dosage, and presence of anionswere found to influence the degradation rate. Photodegradation of organophosphorous pesticides by TiO2/UV and POM/UV exhibited pseudo-first-order reaction kinetics. The electrical energy consumption per order of magnitude for photocatalytic degradation of terbufos and disulfoton were calculated and showed that a moderated efficiency (EEO = 71 and 85 kWh/m3) were obtained in TiO2/UV process. In POM/UV system, the electrical energy efficiency for photocatalytic degradation of terbufos and disulfoton were 288 and 678 kWh/m3, respectively. To obtain a better understanding of the mechanistic details of photocatalysts photodegradation of organo -phosphorous pesticides with UV irradiation, the intermediates of the processes wereseparated, identified, and characterized by the solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) technique. The probable photodegradation pathways were proposed and discussed.
Part II、Novel sensors based on Pt/TiO2-WO3 metal oxide semiconductors have been found to hold much promise as a cheaper alternative for ozone monitoring in commercial used. The sensor response of ozone is owing to the presence of surface oxygen vacancies on the metal oxide. The filling of oxygen vacancies by the ozone traps free charge carriers with consequent measurable increase in resistance. Pt-doping as a promoter of the TiO2-WO3 material to ozone response, and the doped films presented higher sensor response. An impregnation method was used for preparing Pt/TiO2-WO3 materials. The coupled metal oxides were fabricated by the process of mixing various weight ratios (1:1, 1:2, 1:4, 1:6) of TiO2 and tungstic acid. 0.5wt% Pt was added to various weight ratio of TiO2-WO3 materials. Hybrid Pt/TiO2-WO3 material was painted on Al2O3 substrate for ozone sensor. The sensing materials were characterized by SEM, TEM, XRD and UV-VIS spectroscopy. Under 460 nm light source irradiation, the sensor response of Pt/TiO2-WO3 (1:4) was 2712 and recovery time was 85 s. Pt was doped to TiO2-WO3 for enhance electron conductivityand the sensor response was ascended. In addition, the recovery time was reduced remarkably. The slowdown of the electrons and holes recombination on the surface of the sensing material due to the charge transfer of the mixing band is discussed. Pt/TiO2-WO3 is a high activity photocatalyst by visible light irradiation for 2.5 ppm ozone at room temperature.
|
|---|
