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Diaphragm discharge in organic dye solutions
Pajurková, Jana ; Možíšková, Petra (referee) ; Kozáková, Zdenka (advisor)
This Diploma thesis was focused on the degradation of dyes Saturn Red L4B (Direct Red 79) and Saturn Blue LB (Direct Blue 106) by DC diaphragm discharge (DC-DD). Supplied power was between 160 and 180 W. Conductivity and pH were changing at each electrode area during the DC diaphragm discharge, therefore the effect of pH and conductivity changes on the dye solution itself were examined. All samples were measured by UV-VIS spectrometer in the wavelength range of 300–800 nm. No significant dependence of dye absorption spectra on conductivity was observed, while pH significantly affected the absorption curves of dyes. Ageing of dye spectra showed significant changes of Saturn Red L4B. Next task was the comparison of dyes destruction efficiency by DC-DD, audiofrequency diaphragm discharge (AF-DD) and electrolysis. Dye decomposition by AF-DD was not observed at set conditions (voltage of 80–120 V, current of 2.2 A and frequency of 2 kHz). In the case of DC diaphragm discharge the electrolysis played an important role. Decomposition efficiency of the dyes by electrolysis was up to 15 %. The pumping effect in the DC diaphragm discharge was also investigated. Although the individual electrode areas were linked only by a small pinhole in a nonconductive barrier (the pinhole diameter of 0.3 mm), solutions of the anode and cathode compartment interacted with each other up to 10 %. Finally, the degradation products of Saturn Red L4B treated by DC-DD in two electrodes parts are also described. Decomposition products were determined by high performance liquid chromatography (HPLC) combined with the mass spectrometer.
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Study of influence of organic dye structure on their decomposition in the diaphragm discharge in liquids
Pajurková, Jana ; Fasurová, Naděžda (referee) ; Kozáková, Zdenka (advisor)
The main goal of presented thesis is to study the influence of organic dyes structure on its degradation in diaphragm discharge in liquids. Diaphragm discharge is a kind of non-thermal plasma that can be generated in liquids by the application of high voltage. In plasma channels (so-called streamers), many physical and chemical processes are formed. High electrical field, shock waves and last but not least emission of electromagnetic waves in the range of visible and ultra-violet radiation appear among physical processes. The most important chemical process is generation of active species. These species initiate chemical reactions and could attack molecules of organic compounds contained in water solution. The reason why organic dyes were chosen in this study is its visible destruction, because it is related to its decolouration. Further, UV-VIS spectroscopy for the determination of concentration during the experiment can be used. Organic dyes are good models of organic substance often contained in waste water and for which removal classical biological, chemical and physical methods aren’t sufficient. Selected dyes were mostly from the group of azo-dyes: Acid Red 14, Acid Red 18, Acid Yellow 23, Direct Blue 53, Direct Red 79, Direct Red 80, Direct Yellow 29, Food Yellow 3 and further, Acid Blue 74 (indigotic dye) and Direct Blue 106 (oxazine dye). Experiments were carried out in a special batch discharge reactor with the anode and the cathode spaces divided by a non-conductive barrier, where the diaphragm with a pin-hole was placed. Measurement showed different removal in the anode and cathode space. We have supposed it was caused by different streamers features and energetic conditions. Dyes were decomposed with higher efficiency in the anode space where the final concentration reached 40 % of the initial concentration while it remained about 90 % in the cathode space. In this thesis the influence of dyes structure on the dye decomposition by electrical discharge was investigated. Dyes consisted of small molecules and dyes with many substitutes bounded on aromatic ring were decomposed more easily than dyes consisted of big molecules. The shift of characteristic wavelength on both directions (to shorter as well as longer wavelength) was observed during the experiments especially when the Direct dyes were decomposed. This phenomenon was probably due to the formation of intermediate product, which have different characteristic wavelength than the primary compound. In general, colourfulness is given by long conjugated systems of double bonds with substitutes bounded on an aromatic ring. Each change in the molecule structure provides the colour change and this could be the possible reason of the shift of characteristic wavelength. The other task was the comparison of degradation process efficiency by the mean of electrolysis and diaphragm discharge. Results showed that electrolysis (30 W) was more convenient for degradation of dyes consisted of small molecules while diaphragm discharge (130170 W) suited for complex molecules. For degradation of small molecules, oxidation on the anode assumed to be the most effective process that is initiated by electrolysis. For degradation of big molecules, attack of active species produced by the discharge is necessary.
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Getting stress under control by students of grammar schools
Pajurková, Jana ; Provazníková, Hana (advisor)
Stressful situations are an essential part of life. according to Austrian philosopher KR Popper's life could be defined as a constantproblem solving. While reasonable load has one positive effect, the disproportionateburden result in a crisis. While the crisis is also offering its positives (if thatis overcome situation and consequently enriches individual life experience), but it brings with it significant risks. Failure to satisfactorily resolve the crisis affectsthe transition to chronic phase. It is characterized by reduced ability toresolve individual other difficult life situations, reduced adaptability and potential distortions mental equilibrium. Positive effect on coping with the crisis have different psychosocial factors, such as: social support, the possibility of ventilation of emotions, ability to find crisis in some sense, experience with previous stressors, etc. My work aims to contribute to the mapping of possible stress six-year secondary schools for students aged 16 to 18 years. Its aim is to identify possible relation between social factors and coping with stress. Therefore, I its survey of selected groups of respondents, some of which are mutually different social factors: religious school in Prague, Prague bilingual classes school, current grade secondary school in Prague and outside...
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Diaphragm discharge in organic dye solutions
Pajurková, Jana ; Možíšková, Petra (referee) ; Kozáková, Zdenka (advisor)
This Diploma thesis was focused on the degradation of dyes Saturn Red L4B (Direct Red 79) and Saturn Blue LB (Direct Blue 106) by DC diaphragm discharge (DC-DD). Supplied power was between 160 and 180 W. Conductivity and pH were changing at each electrode area during the DC diaphragm discharge, therefore the effect of pH and conductivity changes on the dye solution itself were examined. All samples were measured by UV-VIS spectrometer in the wavelength range of 300–800 nm. No significant dependence of dye absorption spectra on conductivity was observed, while pH significantly affected the absorption curves of dyes. Ageing of dye spectra showed significant changes of Saturn Red L4B. Next task was the comparison of dyes destruction efficiency by DC-DD, audiofrequency diaphragm discharge (AF-DD) and electrolysis. Dye decomposition by AF-DD was not observed at set conditions (voltage of 80–120 V, current of 2.2 A and frequency of 2 kHz). In the case of DC diaphragm discharge the electrolysis played an important role. Decomposition efficiency of the dyes by electrolysis was up to 15 %. The pumping effect in the DC diaphragm discharge was also investigated. Although the individual electrode areas were linked only by a small pinhole in a nonconductive barrier (the pinhole diameter of 0.3 mm), solutions of the anode and cathode compartment interacted with each other up to 10 %. Finally, the degradation products of Saturn Red L4B treated by DC-DD in two electrodes parts are also described. Decomposition products were determined by high performance liquid chromatography (HPLC) combined with the mass spectrometer.
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Study of influence of organic dye structure on their decomposition in the diaphragm discharge in liquids
Pajurková, Jana ; Fasurová, Naděžda (referee) ; Kozáková, Zdenka (advisor)
The main goal of presented thesis is to study the influence of organic dyes structure on its degradation in diaphragm discharge in liquids. Diaphragm discharge is a kind of non-thermal plasma that can be generated in liquids by the application of high voltage. In plasma channels (so-called streamers), many physical and chemical processes are formed. High electrical field, shock waves and last but not least emission of electromagnetic waves in the range of visible and ultra-violet radiation appear among physical processes. The most important chemical process is generation of active species. These species initiate chemical reactions and could attack molecules of organic compounds contained in water solution. The reason why organic dyes were chosen in this study is its visible destruction, because it is related to its decolouration. Further, UV-VIS spectroscopy for the determination of concentration during the experiment can be used. Organic dyes are good models of organic substance often contained in waste water and for which removal classical biological, chemical and physical methods aren’t sufficient. Selected dyes were mostly from the group of azo-dyes: Acid Red 14, Acid Red 18, Acid Yellow 23, Direct Blue 53, Direct Red 79, Direct Red 80, Direct Yellow 29, Food Yellow 3 and further, Acid Blue 74 (indigotic dye) and Direct Blue 106 (oxazine dye). Experiments were carried out in a special batch discharge reactor with the anode and the cathode spaces divided by a non-conductive barrier, where the diaphragm with a pin-hole was placed. Measurement showed different removal in the anode and cathode space. We have supposed it was caused by different streamers features and energetic conditions. Dyes were decomposed with higher efficiency in the anode space where the final concentration reached 40 % of the initial concentration while it remained about 90 % in the cathode space. In this thesis the influence of dyes structure on the dye decomposition by electrical discharge was investigated. Dyes consisted of small molecules and dyes with many substitutes bounded on aromatic ring were decomposed more easily than dyes consisted of big molecules. The shift of characteristic wavelength on both directions (to shorter as well as longer wavelength) was observed during the experiments especially when the Direct dyes were decomposed. This phenomenon was probably due to the formation of intermediate product, which have different characteristic wavelength than the primary compound. In general, colourfulness is given by long conjugated systems of double bonds with substitutes bounded on an aromatic ring. Each change in the molecule structure provides the colour change and this could be the possible reason of the shift of characteristic wavelength. The other task was the comparison of degradation process efficiency by the mean of electrolysis and diaphragm discharge. Results showed that electrolysis (30 W) was more convenient for degradation of dyes consisted of small molecules while diaphragm discharge (130170 W) suited for complex molecules. For degradation of small molecules, oxidation on the anode assumed to be the most effective process that is initiated by electrolysis. For degradation of big molecules, attack of active species produced by the discharge is necessary.
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