Portland State University. Department of Physics
Date of Award
Doctor of Philosophy (Ph.D.) in Applied Physics
1 online resource (xii, 110 pages)
This dissertation presents a method for enhancement of the efficiency and scalability of photocatalytic water purification systems, along with an experimental validation of the concept. A 3-dimensional photocatalyst structure, made from a TiO2-SiO2 composite, has been designed and fabricated for use in a custom designed LED-source illumination chamber of rotational symmetry that corresponds with the symmetry of the photocatalyst material. The design of the photocatalyst material has two defining characteristics: geometrical form and material composition. The design of the material was developed through the creation of a theoretical model for consideration of the system's photonic efficiency. Fabrication of the material was accomplished using a Ti alkoxide solution to coat a novel 3D support structure. The coatings were then heat treated to form a semiconducting thin-film. The resulting films were evaluated by SEM, TEM, UV-vis spectroscopy and Raman spectroscopy. The surface of the material was then modified by implantation of TiO2 and SiO2 nanoparticles in order to increase catalytic surface area and improve the photoactivity of the material, resulting in increased degradation performance by more than 500%. Finally, the efficiency of the photocatalytic reactor was considered with respect to energy usage as defined by the Electrical Energy per Order (EEO) characterization model. The effects of catalyst surface modification and UV-illumination intensity on the EEO value were measured and analyzed. The result of the modifications was an 81.9% reduction in energy usage. The lowest EEO achieved was 54 kWh per cubic meter of water for each order of magnitude reduction in pollutant concentration -- an improvement in EEO over previously reported thin-film based photoreactors.
Fowler, Simon Paul, "Design and Application of a 3D Photocatalyst Material for Water Purification" (2017). Dissertations and Theses. Paper 3648.