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Study of volatile hydrocarbon decomposition in non-thermal plasma of gliding arc at atmospheric pressure
Töröková, Lucie ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
Diploma thesis deals with gliding arc discharge in non-equilibrium plasma, its properties and usage for dissociation of volatile organic compounds. Plasma techniques create a perspective alternative to classical methods such as adsorption, biofilters, thermal processes, freezing and condensation. The method used for analysis of dissociation products is described in the theoretical part as well. Method is gas chromatography and it is combined with mass spectroscopy. The experimental part contains the overall description of GlidArc reactor where volatile organic compounds were dissociated. The volatile organic compound is brought into the reactor from the reservoir by carrier gas (nitrogen); synthetic air was used as working gas. The reactor is connected to the device for sampling. This device has several openings for sampling by SPME fibre method, sorption tubes method and a special opening for probe entry from the device Testo 350 M/XL, which enables instant analysis of low-molecular compounds. GC-MS was used for determination of high-molecular products of dissociation. Products sorbed on SPME fibres were analysed directly, compounds sorbed by active carbon were extracted by carbon disulphide. Samples obtained using SPME fibres were analysed. The major products of the dissociaton were found due to this analysis, those major products are in the case of hexane: pentanal, 4 methyl-3-pentanal, 2-butoxy-ethanol, pentane a 2-hexene. Major products detected when dissociating cyclohexane were: l,3-dimethyl-butane, propanal, cyklohexanone, 5-hexenal a 2-pentyn-1-ol. Major products of xylene dissociation were methyl-benzene, benzaldehyde, 4-methyl-benzaldehyde, 1-nitroethyl-benzene a benzenmethanol. After analysis obtained using sorption tubes showed that mainly the dissociated compound was sorbed, but the products of the dissociation were presented in too low concentration for an adequate analysis. For that reason the sorption tubes were used only for quantitative determination of the compounds depending on the power supply. The dependence of the dissociation of the compounds on the power supply was observed using SPME fibres which were used for quantitative determination. The Results obtained by both obtained techniques were almost in accordance. Speaking of low-molecular compounds, dissociation of all compounds gave the same products, i.e. carbon dioxide, hydrogen, nitrogen oxide, nitrogen dioxide and water. The results show that the dissociation of VOC gives - besides many potentially dangerous dissociation products - significant amounts of nitrogen oxides which is harmful to the environment. Hence it is necessary to be concerned with problems studied in the future mainly with respect to limitation of NOx generation. It will be possible to optimalize the conditions of the VOC dissociation on the basis of future kinetic analysis.
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Study of volatile hydrocarbon decomposition in non-thermal plasma of surface discharge at atmoapheric pressure
Věrná, Jana ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
The main goal of this thesis was to study plasma generated by surface discharge and its application in volatile organic compound destruction. Introduction of this thesis deals with the issue of volatile organic compound. The term of volatile organic compound was defined and explained. Summary of the most important sources of volatile organic compound emissions and possible technics for their elimination was presented. This thesis drew attention on negative aspects of volatile organic compounds on human organism and on the whole environment. The problems of surface discharge and its possible application in various branches are known only few years therefore construction of plasma reactor itself was the first independent step of this work. The plasma reactor was consisted of electrode, which was created from the series of metal stripes each other separated by dielectric barrier. On the surface of the electrode, discharge was regulated and distributed. For the reason of technical limits experiment time was limited up to one minute. The experimental part describes reactor for surface discharge and other parts of apparatus in which degradation volatile organic compound was carried out. Nitrogen was used as carrier gas and it was mixed with air before entering into the reactor. Samples of compounds after degradation process were taken from reactor for the subsequent analysis. Analysis of the products proceeded in a gas chromatogram linked to mass spectrometer. The decomposition products were adsorbed in the SPME filaments or in sorption tubes. The decomposition products were analysed also through the mean of Testo 350 M/XL. This apparatus provided the information on the concentration of small molecules such as CO, H2, NO, NO2 and CxHy Hexane, cyclohexane and xylene were used as VOC examples. Analysis of GC-MS showed decomposition products of hexane, cyclohexane and xylene. The decomposition products were especially various alcohols, ketones, aldehydes and benzene compounds. The apparatus Testo 350 M/XL was unable to detect any CxHy, only large quantity of NO2. This thesis was further focused on possible factors which could have an influence on degradation of compounds, for example input power or different flow of oxygen. It was found that increasing power declined the removal efficiency. The maximum removal efficiency was 87 % for degradation of hexane at the lowest input power. Next part of this thesis was focused on diagnostics of plasma generated in the surface discharge form. The optical emission spectroscopy has been chosen as the best method for plasma characterisation. By this method, various important discharge parameters can be determined, e.g. vibration and rotation temperature. The obtained numeric value of rotation temperature was 840±80 K and vibration temperature was 1880±140 K. The obtained results may be used as a fundament for further study of VOC decomposition in surface discharge.
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Analysis of essences in some plant materials
Koloničná, Markéta ; Svoboda, Zdeněk (referee) ; Mikulíková, Renata (advisor)
The peppermint (Mentha piperita) and the levander (Lavandula angustifolia) are the aromatic herbs with the healing and spices effects. Their essencial oils serve to production of the aromatic substances, they are used in the cosmetic and the food industry. In this thesis were analyzed substances which are contained in levander and peppermint oils. These oils were extracted through the destillation with the water steam, next they were analyzed by the gas chromatograph and the mass spectrometer. The aim of the thesis was found which substances contain these oils. In the levander oils were proofed the highest amounts of the cineole, linalool and the linalyl-acetate. In the peppermint oils were proofed the highest amounts of the menthon and the menthol.
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The possibilities of assessment of free fatty acids in food matrix
Brožová, Michaela ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor´s thesis has a research character and deals with the possibilities of determination of fatty acids in foodstuffs, mainly focused on dairy products. It starts by overview of general characteristics of lipids and fatty acids. The crucial part of thesis represents summary of the methods, which can be used for determination of fatty acids. A special chapter is devoted to determination of free fatty acids. The isolation of lipids/fatty acids from sample matrix is necessary before the determination itself, classic solvent extraction in various applications or several new extraction techniques, e.g. solid phase extraction or supercritical fluid extraction, can be used for this purpose. After the separation of individual lipid fractions, for which the solid phase extraction and/or thin layer chromatography are usually used in practice, the transformation of fatty acids to derivatives, which are suitable for following analytical determination, is often necessary. Gas chromatography with the flame-ionization or mass selective detection is most often used for determination and therefore fatty acids are converted to substantially more volatile methyl esters. In some special cases high performance liquid chromatography and/or thin layer chromatography can be used.
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Spray &Trap Method for Analysis of Residual Toxic Agents in Water
Vlčková, Lenka ; Podborský, Vladimír (referee) ; Brno), (VTÚO (advisor)
This work deals with verification of the analysis of precursors or degradation products of toxic compounds in the air and water through GC/MS by method of the thermal desorption or combination of methods "spray & trap" followed by the thermal desorption transfer the sample into the analyzer. Toxic compounds triethyl phosphate (TEP) and diisopropylmethyl phosphonate (DIMP) were choosen for the analysis. For choosen compounds has been optimized desorption time, for TEP 240 seconds and DIMP 210 seconds. Then the calibration curve was made for different concentrations of compounds DIMP and TEP. On the basis of these measurements was tested the possibility of determining the concentration of the compound in water sample using of method "spray & trap“. Thanks to the high solubility of compounds TEP and DIMP in water, higher boiling temperatures in comparison with boiling temperature of water, and extraction at room temperature, it was not possible to detect used compounds. Therefore, the analysis of compounds DIMP and TEP in the water by method "spray & trap“ seems inappropriate.
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Analytical methods Used in the Studies on Chemical Ecology of Termites
Krasulová, Jana ; Hanus, Robert ; Sillam-Dusses, David ; Žáček, Petr ; Jiroš, Pavel ; Šobotník, Jan ; Kalinová, Blanka ; Bosáková, Z. ; Valterová, Irena
In this paper, I review our recent results on the trail-following communication in the Neotropical termite Glossotermes oculas (Serritermitidae) and the defensive chemistry of the African termite Psammotermes hybostoma (Rhinotermitidae). These findings belong to our current project focused on chemical ecology of critical termite genera from families Rhinotermitidae and Serritermitidae.
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