Date of Award

6-2011

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Mechanical Engineering

First Advisor

Ann Anderson

Language

English

Keywords

indoors, air quality, aerogels, flow rates

Abstract

Indoor air has been shown to be four to five times more polluted than outdoor air. Titania-silica aerogels can photocatalytically oxidize volatile organic compounds found in indoor air. Aerogels are the lightest known solid with 90-99% air by volume. Titania-silica aerogels were fabricated in seven to nine hours using the Rapid Supercritical Extraction method and properties compared well to those published in the literature. Bulk density ranges between 0.025 and 0.04 g/cm3. Skeletal density ranges between 1.75 and 2.75g/cm3. BET surface area ranges between 200 and 700 m2/g. BJH pore distribution showed distinct differences between silica and titania aerogels. FTIR results showed the presence of anatase titania, which has been shown to be a key component in photocatalytic oxidation. Photocatalytic oxidation abilities were tested using methylene blue in an aqueous solution in both natural sunlight and using a solar simulator. Results showed that methylene blue can be decomposed using photocatalyic oxidation in the presence of UV and visible light. A flow-type photocatalytic oxidation test apparatus was designed and built to test the decomposition rate of toluene at various flow rates in the presence of water vapor. Humidified toluene vapor flowed through samples of titania-silica aerogel placed in a reactor vial, illuminated by four 4W UV blacklights surrounding the vial. The effluent stream was analyzed using two different 10.6 eV lamp handheld photoionization detectors. Up to a 99% reduction in toluene concentration was seen. Most of this reduction is likely due to adsorption of toluene in the aerogel material, although preliminary results show photocatalytic oxidation also does occur.

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