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PAH bond to nanoparticles of atmospheric aerosol: substrate specifity.
Bendl, Jan ; Hovorka, Jan (advisor) ; Cajthaml, Tomáš (referee)
Polycyclic aromatic hydrocarbons (PAHs) are reviewed including their chemical and chemical- physical features, their impact on health and the environment. Different behaviour of PAHs is mentioned. The detailed instruction for the measurement using high-volume cascade impactor BGI 900 (Hi-Vol) is described. Cleaning, equilibration, weighting, protection against contamination of the substrates and technique of the measurement were introduced. The experiment was done: under the last teflon back-up filter the extra PUF substrate was placed, where after the air exposition the significant amounts of gaseous phase of phenanthrene, anthracene, fluoranthene, pyrene and benzo(a)anthracene were captured. The extent of the volatile PAHs capture correlated positively with the vapour pressure (ranging from 10-4 to 10-1 Pa.). The other measured PAHs (coronene, benzo(ghi)perylene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene and indeno(1,2,3-cd)pyrene) with vapour pressure from 10-5 to 10-10 Pa were not captured. The experiment found out that polyurethane (PUF) substrates captured in noticeable amount the volatile phase of PAHs and therefore the correction for the capture of gaseous phase in the particle size fractions of PAHs was calculated. The deduction for the...
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Characterization of the chemical composition of the tar produced in the gasification of biomass
Mahelová, Zora ; Vávrová, Milada (referee) ; Čáslavský, Josef (advisor)
Biomass is a renewable source of energy and represents an acceptable alternative to fosil fuels. Usable methods of energetic use of biomass are combustion and gasification. Main interest is focused on gasification in last years. Gasification is based on conversion of organic material to usable gaseous product called syngas, which can be used as a fuel for energy production. Large amount of tar is formed as a by-product of incineration and gasification of biomass. Tar is composed by various mixture of organic substances, has a negative effect on operating conditions and is a potential threat to environment. Experimental part of this study was focused on analysis of tar obtained by gasification of various kind of biomass. Selected groups of hydrocarbons and oxygen compounds were identified in analysed samples. Individual biomass samples were compared regarding to determined relative content of selected substances. Analysis was done by complete twodimensional gas chromatography with mass spectrometric detection (GCxGC/TOF-MS).
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TEMPERATURE INFLUENCE ON DESORPTION AND DETERMINATION OF BIOACCESSIBLE PAHS
Čvančarová, Monika ; Pokorná, Lenka ; Velebová, R. ; Najmanová, P. ; Cajthaml, Tomáš
Hydrophobic organic pollutants tend to adsorb onto soil particles which can cause a significant decrease in their bioaccessible fractions. Definition of the bioaccessibility is currently not unified; however it represents a part of total PAHs amount which is potentially available for biological processes. It is an important parameter which can be used for prediction of microbial degradation and environmental risk evaluation. This paper studies desorption behavior of PAHs at 20 and 60˚C. The desorption of PAHs from long-term contaminated soils was evaluated using resin Amberlite XAD- 2. A two-phase desorption model was used to calculate the desorption kinetic curves and F fractions which represent bioaccessible amount of PAHs. The results showed that the desorption of PAHs was significantly influenced by temperature. The greatest differences in the desorption behavior were observed at 5–6 ring PAHs. We compared the F fractions and the rate constants of individual PAHs which were determined at 20 and 60˚C. The results were also compared with sequential supercritical fluid extraction which has been already used for prediction of microbial degradation.
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