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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 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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