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HETEROGENOUS PHOTOCATALYSIS ON AEROSOL PROCESSED NANOSTRUCTURED TITANIA PARTICLES: ROLE OF PARTICLE SIZE
Citation:
Almquist, C. B., P. Biswas, AND E SahleDemessie*. HETEROGENOUS PHOTOCATALYSIS ON AEROSOL PROCESSED NANOSTRUCTURED TITANIA PARTICLES: ROLE OF PARTICLE SIZE. Presented at AiCHe Annual Meeting, Reno, NV, 11/2001.
Description:
Heterogenous photocatalysis with TiO2 has been extensively investigated as a method to oxidize organic pollutants in water and air, including phenols, chlorinated hydrocarbons, and other hydrocarbons. In addition, the use of titanium dioxide as a photocatalyst has also been demonstrated for the capture of sulfur and toxic metal species in combustion exhaust streams (1), for use in self-cleaning tiles (2), and for green synthesis of partial oxygenates (3). The most attractive feature of this oxidation technology is that complete oxidation of organic pollutants can be achieved at ambient temperature and pressure. However, there are developmental challenges to be overcome before heterogenous photocatalysis becomes widely used in large scale processes. Two of these challenges are 1) the relatively low quantum efficiencies of the catalyst, and b) the requirement of near ultraviolet light energy (?<380nm) for activation. A flame aerosol route to synthesize pristine and doped, nanostructured titania powders and films will be described, and followed by a discussion of the solid state properties as a function of size. A kinetic model describing the role of operating variables and primary particle size in the heterogenous photocatalysis applications will be presented and validated by comparing to experimental results. Localization or size quantization effects on band-gap energies, resultant photoactivity and the variation of Raman modes as a function of particle size in nanometer size ranges will also be presented.