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Photocatalytical degradation of selected volatile organic compounds in emission test chambers
(2014)
This work focuses on the photocatalytical degradation of selected volatile organic compounds (toluene, butyl acetate, phenol and limonene) under UV-light and blue LED-light (λ = 444 nm) at different relative humidities. Ceramic tiles coated with titanium dioxide were used as photocatalytical active material. The experiments were performed in 20 l emission test chambers with two different kinds of pollutant supply. Toluene was the compound with the highest degradation rate in all performed experiments. A degradation rate of 24 % was obtained under blue LED-light and a relative humidity of (50 ± 5)% and a degradation rate up to 80 % was obtained under UV-light in dry air.
Volatile Organic Compounds (VOC) are ubiquitous in the indoor air since they are emitted from materials used indoors. Investigations of these materials are mostly carried out in emission test chambers under controlled climatic conditions. Reference materials are an important tool for quality assurance/Quality control of emission test chamber measurements but so far they are not commercially available. In this study, a new approach was tested to develop an appropriate reference material with homogenous and reproducible emission of the VOC with well measurable air concentrations in emission test Chambers larger than 20 L at air change rates of 0.5 - 1 /h.
Thermoplastic Polyurethane (TPU) was selected as Matrix material which was impregnated with 2,2,4- trimethyl-1,3-pentanediol monoisobutyrate (texanol) as test VOC using compressed carbon dioxide. An optimization of the impregnation parameters such as temperature, pressure, time, VOC injection volume and TPU sample size was performed until the targeted area specific Emission rate (SERa) value was reached. Further aspects like process control, storage effects and correlation of the sample size to the emission rate were investigated. It was found that the SERa immediately after sample preparation were not reproducible between the batches but became unified 10 days after loading into the test chamber indicating the necessity of aging before use. SERa between 13,000 and 18,000 mg m-2 h-1 were obtained, and the impregnated materials could be well stored in aluminum-coated polyethylene foil for at least seven weeks without significant losses. Furthermore, the impregnation of styrene and the SVOC 2,6-diisopropylnaphthalene was tested.