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Diagnostics of plasma generated in mixtures of water and alcohols
Adámková, Barbora ; Slavíček, Pavel (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis is aimed to the corona-like discharge in solutions of alcohols, specifically in ethanol, methanol, glycerol, butanol and isopropyl alcohol. The electric discharge was diagnosed by two methods. The first method was the measuring of electrical characteristics. Current-voltage characteristics were constructed from the measured average values of voltage and current. The breakdown voltages were determined from the current-voltage characteristics. The breakdown voltages of the individual alcohol solutions were dependent on the alcohol concentration, polarity of the electrodes in the reactor and solution conductivity. The breakdown voltage was determined for solutions of butanol, glycerol and isopropyl alcohol with a concentration of 20 vol. % and conductivity of 200 µS. The highest value of the breakdown voltage was determined for solution of glycerol at 580 V. The lowest voltage at which the discharge was observed was estimated for butanol (320 V), but due to the limited miscibility with water this value is inaccurate, and therefore in the second part of experiment butanol was not used. Alcohol series was supplemented with methanol. The second diagnostic method was the proton ionization mass spectrometry with the time of flight analyzer. The products formed in the reactor due to the plasma discharge were identified from the mass spectrum. Mostly, aliphatic hydrocarbons and their radicals were detected. The amount of products was observed in the dependence on the changing experimental conditions: alcohol concentration in the solution, the polarity of the electrodes in the reactor and the duration of the discharge. Only a small amount of compounds were detected in methanol. However, more molecules were formed with the increasing carbon chain in the alcohol molecule. More compounds were also detected with the increasing alcohol concentration and in case of the negative polarity of the main electrode. The formation of acetaldehyde as a typical discharge product was studied in details. Its production in time was observed and the reaction pathways of its formation in the ethanol solution were suggested.
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Diagnostics of plasma generated in mixtures of water and alcohols
Adámková, Barbora ; Slavíček, Pavel (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis is aimed to the corona-like discharge in solutions of alcohols, specifically in ethanol, methanol, glycerol, butanol and isopropyl alcohol. The electric discharge was diagnosed by two methods. The first method was the measuring of electrical characteristics. Current-voltage characteristics were constructed from the measured average values of voltage and current. The breakdown voltages were determined from the current-voltage characteristics. The breakdown voltages of the individual alcohol solutions were dependent on the alcohol concentration, polarity of the electrodes in the reactor and solution conductivity. The breakdown voltage was determined for solutions of butanol, glycerol and isopropyl alcohol with a concentration of 20 vol. % and conductivity of 200 µS. The highest value of the breakdown voltage was determined for solution of glycerol at 580 V. The lowest voltage at which the discharge was observed was estimated for butanol (320 V), but due to the limited miscibility with water this value is inaccurate, and therefore in the second part of experiment butanol was not used. Alcohol series was supplemented with methanol. The second diagnostic method was the proton ionization mass spectrometry with the time of flight analyzer. The products formed in the reactor due to the plasma discharge were identified from the mass spectrum. Mostly, aliphatic hydrocarbons and their radicals were detected. The amount of products was observed in the dependence on the changing experimental conditions: alcohol concentration in the solution, the polarity of the electrodes in the reactor and the duration of the discharge. Only a small amount of compounds were detected in methanol. However, more molecules were formed with the increasing carbon chain in the alcohol molecule. More compounds were also detected with the increasing alcohol concentration and in case of the negative polarity of the main electrode. The formation of acetaldehyde as a typical discharge product was studied in details. Its production in time was observed and the reaction pathways of its formation in the ethanol solution were suggested.
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