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Study of chemical processes initiated by electrical discharge in liquids
Možíšová, Aneta ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
This Bachelor´s thesis in the first part describes the process of ignition of the plasma discharge in water solutions, the generation of the particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on specific cases of the use of the plasma discharge in the environment of selected electrolyte, phosphates were selected for individual experiments and for the comparison of sodium chloride. Phosphates were chosen mainly because of their stable pH as a possible benefit in discharge. The aim is to obtain the most ideal environment for the ignition of the plasma discharge and to optimize the method, which could subsequently be used for medical purposes, especially when sterilizing tools
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Hydrogen peroxide generation by the microwave plasma jet
Staškovanová, Denisa ; Mazánková, Věra (referee) ; Kozáková, Zdenka (advisor)
This Bachelor thesis deals with the generation of hydrogen peroxide by the microwave plasma jet in distilled and tap water. The main goal was to characterize the amount of generated hydrogen peroxide depending on various experimental conditions and to determine its stability. A titanium reagent was used to determine if hydrogen peroxide was present in the sample. The method for determination of hydrogen peroxide concentration was spectrophotometry. In conclusion, differences in the concentration of hydrogen peroxide are formulated according to the change in experimental conditions, its stability in plasma activated water and stability in complex with the titanium reagent. Differences between the generation in distilled and tap water are also described.
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Electrochemical evolution of hydrogen peroxide for biotechnological applications
Runštuková, Nikola ; Kratochvíl, Matouš (referee) ; Ehlich, Jiří (advisor)
This master‘s thesis deals with the connection of two distinct fields, electrochemistry and biotechnology, where electrochemically generated peroxide was subsequently used in bacterial cultivation. The peroxide was synthesized in an electrolytic cell by reducing oxygen at the cathode to which suitable electrical potential was applied. The aim of this thesis was to investigate the dependence of the amount of hydrogen peroxide produced on a few selected parameters, such as cathode potential, electrode material, the geometry of the measuring cell, or the stirring speed, and then to apply these findings in the continuous stressing of the bacterium Cupriavidus necator H16, in order to increase the production of polyhydroxyalkanoates. The selected parameters were first tested in small-scale measuring cells and then experiments were carried out on a larger scale, in Erlenmeyer flasks. During the experiments, the amount of electric current produced was measured and also the peroxide concentration was examined spectrophotometrically along with the oxygen concentration measured by using an optical sensor. Based on the obtained results, bacteria were cultivated in flasks with a built-in system of steel electrodes, due to which oxidative stress in the form of in situ generated hydrogen peroxide was continuously applied. The bacterial cultures were evaluated by measuring the change in optical density, gravimetric analysis and GC-FID analysis. It was found that even small amounts of hydrogen peroxide (~25 M) can induce a stress response in the organism in the form of increased polyhydroxybutyrate (PHB) synthesis. A percentage increase in the PHB content of the biomass was achieved, however, the overall polymer yield was lower due to lower biomass growth.
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Hydrogen peroxide generation by the microwave plasma jet
Staškovanová, Denisa ; Mazánková, Věra (referee) ; Kozáková, Zdenka (advisor)
This Bachelor thesis deals with the generation of hydrogen peroxide by the microwave plasma jet in distilled and tap water. The main goal was to characterize the amount of generated hydrogen peroxide depending on various experimental conditions and to determine its stability. A titanium reagent was used to determine if hydrogen peroxide was present in the sample. The method for determination of hydrogen peroxide concentration was spectrophotometry. In conclusion, differences in the concentration of hydrogen peroxide are formulated according to the change in experimental conditions, its stability in plasma activated water and stability in complex with the titanium reagent. Differences between the generation in distilled and tap water are also described.
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Study of chemical processes initiated by electrical discharge in liquids
Možíšová, Aneta ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
This Bachelor´s thesis in the first part describes the process of ignition of the plasma discharge in water solutions, the generation of the particles that are generated during the discharge and their subsequent analysis by appropriate analytical methods. The second part focuses on specific cases of the use of the plasma discharge in the environment of selected electrolyte, phosphates were selected for individual experiments and for the comparison of sodium chloride. Phosphates were chosen mainly because of their stable pH as a possible benefit in discharge. The aim is to obtain the most ideal environment for the ignition of the plasma discharge and to optimize the method, which could subsequently be used for medical purposes, especially when sterilizing tools
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