| Summary: | 碩士 === 國立高雄應用科技大學 === 化學工程與材料工程系 === 99 === The synthesis and modification of nano titanium dioxide powders is usually carried out under long reaction time with complex and multiple processes. In order to simultaneously synthesize and modify titanium dioxide powders in one step, an atmospheric-pressure microwave plasma was used by spraying the titanium tetrachloride solution as precursors passing through the heat cavity resonator at 900 W and 20 slpm. There were four types of processes in this study, including N2/O2 mixed gases (TiO2), inlet NH3/N2/O2 gases, N2/O2 gases with H2PtCl6 solution, and NH3/N2/O2 gases with H2PtCl6 solution were fed, and then reacted with TiCl4(aq) aerosols for producing unmodified TiO2, N-doped TiO2, Pt-modified TiO2, and Pt/N-TiO2 powders, respectively.
The mass and calculated size-fractionated particle samples were collected by 14-stage impactors (MOUDI). The results showed that the most of particles (in number) were primary particles and were in 5~10 nm stage impactor, reaching 95.0~98.9% of total particle number. Moreover, the normalized particle number percentage was as high as 316~328. The SEM and TEM photographs of powders showed that the TiO2 powders were sphere, and the large particles of powders should be aggregated by the primary particles. By electron diffraction patterns, the crystal phase of the powder is mainly anatase. Elemental analysis by XPS were used to confirm the N-doping for N-TiO2 (N = 0.47 wt %), the addition of platinum atoms in Pt-TiO2 powders (Pt = 0.23 wt %), and the simultaneous modification of Pt and N foe the Pt/N-TiO2 powders (Pt = 0.19 wt %; N = 0.41 wt %).
Comparison of the photocatalytic efficiency between unmodified, modified TiO2 and commercial P25 for degradation of methylene blue dye solution showed that the photocatalytic efficiency of modified TiO2 is consistent with commercial P25 powders for the duration of UV-light degradation. By visible light degration, the degradation efficiency of methylene blue dye solution is apparently better for the modified TiO2 than P25.
|
|---|
