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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 chemical processes in the gliding arc discharge by optical emission spectroscopy
Maďarová, Štefánia ; Töröková, Lucie (referee) ; Mazánková, Věra (advisor)
The aim of the bachelor thesis is to study the chemical processes of the glow discharge and the sliding arc under the post discharge conditions. The post discharge or afterglow plasma means that the external source of energy is removed from the system and the relaxation process can start. The experiments in bachelor work were performed under the different experimental conditions, for various pressures and gas mixtures. The theoretical part briefly describes term plasma and kinetic processes occurring in plasma generated by electrical discharges. Also there is described the problem of Titan’s atmosphere and possibility of mimic it by the gliding arc discharge. In the experiments, pure nitrogen and a gaseous mixture of nitrogen and methane were used at the same flow rate and different pressures. Optical Emission Spectroscopy (OES) and Gas Chromatography-Mass Spectrometry (GC-MS) were used to analyze chemical reaction products. The glow discharge was generated by a DC voltage source and the measurement was in flow mode. The total gas pressure ranged from 1 000-4 000 Pa at a nitrogen flow rate of 400 ml / min and methane of 0.025 ml / min. The current was in the range of 85-150 mA. In all experimental conditions, a well-known phenomenon called “pink afterglow” was observed. This phenomenon corresponds to the maximum intensity of radiation in a stagnant discharge, exhibiting a significant increase in characteristic pink radiation. The optical emission spectra of the discharging discharge were scanned in the wavelength range 540-640 nm. Three spectral nitrogen systems (the first and the second positive and the first negative ones) have been identified in the measured spectra, they have maximum values in the so-called " "Pink-afterglow". These maxims dropped with increasing pressure and shifted to a later decay time.
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Diagnostics of active particles generated by the interaction of plasma microwave discharge with liquids
Kovaříková, Kateřina ; Töröková, Lucie (referee) ; Kozáková, Zdenka (advisor)
The first part of this Bachelor’s thesis describes problems of electric discharges in gas and on a surface of water solutions. It focuses on the generation of the active particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on identification of the active particles that are generated during the microwave discharge in gas phase and during the interaction with water solution surface. The aim is to determine the influence of experimental conditions on the information of the active particles, specifically the nitrates and nitrite ions.
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Study of Chemical Processes in Titan Atmosphere Initiated by Discharge in Electrode Configuration Like Gliding Arc Discharge
Töröková, Lucie ; Zahoranová, Anna (referee) ; Žabka,, Ján (referee) ; Krčma, František (advisor)
The aim of this work is the study of plasma processes and the synthesis of organic compounds due to electric discharge generated in gas mixture corresponding to the composition of the atmosphere of Saturn's largest moon Titan. This study focuses on the mimic of Titan's atmosphere at atmospheric pressure and ambient laboratory temperature. The chemical composition of Titan's atmosphere is very similar to atmosphere of prehistoric Earth. Many articles have been published with theoretical model-research, and laboratory experiments are the pursuit of their interconnection. The main aim of thesis is the identification of synthesized gaseous organic, amino, imino and cyano compounds by use to various analytical methods such as the PTR-MS, FTIR and GC-MS. The OES and electric measurements were applied to the determination of selected electric discharge parameters. The gaseous products and radicals formed in an atmospheric discharge fed by different mixtures of N2:CH4 (0,5 up to 5 % of CH4) operated in a flowing regime at the total gas mixture flows from 50 to 200 sccm at different discharge currents from 15 up to 40 mA were determined. A part of experiments was carried out with admixtures of CO2 and hydrogen. This first part of results has been obtained using OES in dependence on the gas mixture composition and supplied power. The bands of the nitrogen second positive and the first negative systems, CN violet system and Swan system of C2 were recorded. Besides them, atomic lines H, H, and C (in the second order) were also observed. These spectra allowed calculation of rotational and vibrational temperatures. FTIR in situ analysis of the gaseous products showed presence of various nitrile compounds and hydrocarbons in all experiments. The HCN, C2H2, NH3 were the main products generated in our system. The dependences of their concentrations on various experimental parameters were measured. The other part of this work was devoted to estimate the influence of CO2 traces addition on the reactivity in the gaseous mixtures mentioned above. Besides the main products mentioned above, CO2 and CO were detected and also some more complicated oxygen molecules has been confirmed but not estimated because of FTIR spectra complexity. In the case of hydrogen traces addition into the reaction gas mixture, no other compounds were determined. Impurities of CO2 as well as hydrogen have a great positive influence on the production efficiency of the major generated compounds at all conditions. The more detailed gaseous products analyses were carried out using the in situ PTR-MS. A huge number of different molecular structures containing nitrile groups (–CN), amino groups (–NH2, –NH–, –N CH3CN > C2H5CN. Besides them, many other hydrocarbons and nitriles were detected. Presence of all compounds was studi
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Determination of the ozone concentration generated by dielectric barrier discharge.
Manduchová, Ivana ; Töröková, Lucie (referee) ; Mazánková, Věra (advisor)
The bachelor´s thesis is focused on the study of determination of the ozone concentration generated by dielectric barrier discharge from high-purity oxygen gas of 99,999 9 %, at changes in different experimental conditions, using absorption spectrometry. The emphasis was put also equally on the comparison of two representatives of the basic methods determining the concentration of ozone. In the theoretical part are described characteristic properties of ozone and fields of utilization, methods of ozone generation, experimental methods of determining the concentration of generated ozone and microbicidal effects of ozone. In the experimental part was investigated the generation of ozone created by interaction of oxygen with oxygen adsorbed on the walls of ozonizer depending on variation of experimental conditions. Multiple series of experiments were conducted, where the changing variable of experimental conditions was the change of voltage on power supply, the flow change of oxygen and the change of reaction time period. Besides of these, there has been also examined the applicability of determining the concentration of ozone using iodometric titration in comparison with the method of UV absorption at conditions used in the experiment. Ozone was generated by assembly of two identical cylindrical ozonizers made from stainless steel functioning on principle of dielectric barrier discharge using dielectric from alumina.
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Study of DC discharge products in CO2 + N2 mixture
Kostyleva, Kseniia ; Töröková, Lucie (referee) ; Mazánková, Věra (advisor)
The bachelor´s thesis is focused on the study of products of DC glow discharge in nitrogen, methane and carbon dioxide gas mixtures. Different diagnostic techniques were used for measure their concentrations (PTR-MS-TOF mass spectrometer and a TESTO 350 M/XL instrument). The theoretical part describes principle of mass spectrometry, types of analysers and ionizers. There are also described various types of electrical discharges, including the Glid-Arc discharge, which was used during the measurement. In addition, one of the theories of the origins of life is described. There is also description of Titan's atmosphere, which was chosen due to the similarity of its atmosphere with the atmosphere of the early Earth. In the experimental part the discharge products and their concentration under different experimental conditions are shown.
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Diagnostics of active particles generated by the interaction of plasma microwave discharge with liquids
Kovaříková, Kateřina ; Töröková, Lucie (referee) ; Kozáková, Zdenka (advisor)
The first part of this Bachelor’s thesis describes problems of electric discharges in gas and on a surface of water solutions. It focuses on the generation of the active particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on identification of the active particles that are generated during the microwave discharge in gas phase and during the interaction with water solution surface. The aim is to determine the influence of experimental conditions on the information of the active particles, specifically the nitrates and nitrite ions.
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Study of DC discharge products in CO2 + N2 mixture
Kostyleva, Kseniia ; Töröková, Lucie (referee) ; Mazánková, Věra (advisor)
The bachelor´s thesis is focused on the study of products of DC glow discharge in nitrogen, methane and carbon dioxide gas mixtures. Different diagnostic techniques were used for measure their concentrations (PTR-MS-TOF mass spectrometer and a TESTO 350 M/XL instrument). The theoretical part describes principle of mass spectrometry, types of analysers and ionizers. There are also described various types of electrical discharges, including the Glid-Arc discharge, which was used during the measurement. In addition, one of the theories of the origins of life is described. There is also description of Titan's atmosphere, which was chosen due to the similarity of its atmosphere with the atmosphere of the early Earth. In the experimental part the discharge products and their concentration under different experimental conditions are shown.
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Study of chemical processes in the gliding arc discharge by optical emission spectroscopy
Maďarová, Štefánia ; Töröková, Lucie (referee) ; Mazánková, Věra (advisor)
The aim of the bachelor thesis is to study the chemical processes of the glow discharge and the sliding arc under the post discharge conditions. The post discharge or afterglow plasma means that the external source of energy is removed from the system and the relaxation process can start. The experiments in bachelor work were performed under the different experimental conditions, for various pressures and gas mixtures. The theoretical part briefly describes term plasma and kinetic processes occurring in plasma generated by electrical discharges. Also there is described the problem of Titan’s atmosphere and possibility of mimic it by the gliding arc discharge. In the experiments, pure nitrogen and a gaseous mixture of nitrogen and methane were used at the same flow rate and different pressures. Optical Emission Spectroscopy (OES) and Gas Chromatography-Mass Spectrometry (GC-MS) were used to analyze chemical reaction products. The glow discharge was generated by a DC voltage source and the measurement was in flow mode. The total gas pressure ranged from 1 000-4 000 Pa at a nitrogen flow rate of 400 ml / min and methane of 0.025 ml / min. The current was in the range of 85-150 mA. In all experimental conditions, a well-known phenomenon called “pink afterglow” was observed. This phenomenon corresponds to the maximum intensity of radiation in a stagnant discharge, exhibiting a significant increase in characteristic pink radiation. The optical emission spectra of the discharging discharge were scanned in the wavelength range 540-640 nm. Three spectral nitrogen systems (the first and the second positive and the first negative ones) have been identified in the measured spectra, they have maximum values in the so-called " "Pink-afterglow". These maxims dropped with increasing pressure and shifted to a later decay time.
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Analytické metody pro stanovení kyseliny jablečné a vinné ve víně
Töröková, Lucie
Malic acid and tartaric acids are the most important organic acids in grape juice and wine. They can be detected in liquid samples by several different analytical methods. The aim of this work was to compare various analytical techniques used for the qualitative and quantitative analysis in grape juice and wine. Individual methods were divided into 5 groups: chromatographic, electrochemical, spectroscopic, enzymatic methods and titration. These methods were described in details and summarized. Some of these methods are already in decline or they are utilized by small winemakers, only. In contrast, the development of instrumentation technique is still ongoing. Detection limits are constantly improved and various machine combinations are tested. The most commonly used methods include chromatography techniques in combination with various types of detectors, its connection with other devices, and even their series connection.
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