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Influence of plasma activated water on seed germination and quality of corn
Kovařík, Martin ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
The bachelor's thesis deals with the effect of plasma-activated water on corn germination. After water comes into contact with plasma, the water changes its chemical composition and thus, it acquires new properties that can be used in agriculture. The theoretical part is divided into two basic parts. At the beginning of the first part, plasma is briefly characterized, and then this part deals with plasma-activated water, its formation, physical and chemical properties, and at the end of this part, its use. The second part of the theoretical part is devoted to the germination of plants, external influences affecting germination and statistical evaluation of germination. At the end of the theoretical part, this thesis deals with the ecotoxicity of plants. The content of the experimental part was the preparation of PAW, its subsequent application to corn seeds and the study of its effect on germination and plant quality. PAW was created from distilled or tap water using three different plasma systems and the effect of each PAW on the seeds was compared with that of each control sample. The obtained results indicate a positive effect of PAW on seed germination, but the final hypothesis would require more extensive experiments in different environments, especially in soil.
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Influence of plasma treated water on the plant growth and vitality
Vozár, Tomáš ; Zahoranová, Anna (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis deals with the effect of plasma activated water on plant growth and vitality. By interaction of plasma with water, water acquires new unique properties that can be used in agriculture. The theoretical part deals with the basic properties of plasma, possibilities of preparation of plasma activated water in laboratory conditions, its physico-chemical characterization, and possibilities of its use in agriculture. In the next part, plant photosynthesis is discussed in connection with chlorophyll fluorescence, which measures the activity of photosystem II. Activity is an indicator of plant vitality, under environmental changes. At the end of the theoretical part, there are listed further possibilities for the analysis of plant material and food, such as elemental analysis, sensory analysis, and determination of dry matter content. Within the experimental part, plasma activated water (PAW) was prepared using plasma nozzle with introduced gas mixture that was immersed in the treated liquid. Further, plasma activated water was characterized and applied to radish plants. The effect of PAW on the plant growth and vitality was observed. The effect on the growth was observed through determination of fresh weight and dry matter content, the effect on vitality was assessed through chlorophyll fluorescence and the NDVI index. In the end, the effect on the content of stored elements C, H, O, and N in plants was determined and a sensory analysis was performed. The results show positive effects of plasma activated water on the plant growth and its sensory parameters such as appearance, taste, or spiciness. The results further show that PAW does not adversely affect plant vitality. This experiment should be continued by further indoor replication of the experiment to confirm obtained results and then, by moving the experiment to exterior in a form of field experiments.
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Influence of plasma and plasma activated water on fungi Aspergillus niger
Žitný, Michal ; Čechová, Ludmila (referee) ; Kozáková, Zdenka (advisor)
The thesis deals with the issue of decontamination of Aspergillus niger mold using plasma, plasma-activated water and their combination. The theoretical part concerns the effects on the general properties of plasma, its generation, effects on microorganisms known so far and its use in industry with a special focus on medicine. It also focuses on the generation and characterization of plasma-activated water, its effects on bacteria, yeasts and fungi and its use. It also deals with the description of fungi, their occurrence and their sterilization. Part of the theory was aimed directly at the fungus Aspergillus niger. Its cultivation and its industrial uses, such as its use for the cultivation of citric acid, were described here. The experimental part deals with the characterization of plasma-activated water generated using a torch jet. The influence of the supplied power on the formation of particles in plasma-activated water was monitored. The decontamination effect of the plasma, generated by the torch jet, alone and in combination with plasma-activated water generated by alternating and direct current is monitored. The characterization of plasma activated water was performed with 20 ml of distilled water at a carrier gas rate of 2 l/min and a power of a microwave source of 9 and 12 W. The decontamination effect of plasma and its combination with plasma-activated water was observed by inoculating 100 l of a ten-fold and a hundred-fold diluted treated mold culture on Petri dishes with malt agar. The evaluation of the effect was carried out by counting the grown fungal colonies and subsequent comparison with control samples. All measured and obtained data were processed in the results. Plasma activated water generated by the torch jet has been found to contain higher concentrations of nitrogenous substances and lower concentrations of hydrogen peroxide, with the generated nitrate concentrations being higher at lower output than at higher output. DC-generated plasma activated water containing low concentrations of nitrogenous species and a very high concentration of hydrogen peroxide compared to PAW generated by a torch jet. Furthermore, plasma-activated water generated using a high frequency source contains minimal concentrations of nitrogenous substances and slightly elevated concentration of hydrogen peroxide in regard to torch jet PAW. The highest decontamination effect of all the methods used was the combination of plasma and plasma activated water, prepared by a plasma nozzle using direct voltage, when the plasma was applied first. On the contrary, the least effective method was the application of plasma and plasma activated water, generated by high frequency voltage. Limiting oxygen access had almost no effect on direct plasma treatment, but other methods were significantly affected by it. The greatest difference in decontamination effect was observed for the combination of plasma and plasma activated water, generated by high frequency current, where the difference was up to 30 %, but all methods had a significant decontamination effect compared to the control.
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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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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 electrolyte influence on diaphragm discharge stability and efficiency
Němcová, Lucie ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
This thesis is focused on so-called diaphragm discharge, which is one kind of electric discharges in liquid, which belongs among so-called AOP´s techniques, still more used for water cleaning in the present. One of effectiveness and stability indicators of diaphragm discharge is generation of hydrogen peroxide. In theoretical part, detail principle description of electric discharge in liquid is situated. Further, properties of electrolyte are introduced and general spectrophotometric method of obtained sample determination is described. In experimental part, a full procedure of experiment is introduced. Next part containing results and discussions introduces particular results of individual measurements and their reasons. Final chapter is the end, which forms total summary and evaluation of all results. By the application of all chosen electrolytes in solution at diaphragm discharge formation of hydrogen peroxide has appeared. Inorganic and organic electrolytes were used. As inorganic electrolytes following salts were selected – solutions of halogenides, next sodium nitrate as a representative of nitrates, potassium dihydrogenphosphate as a representative of phosphates, etc. Representative of organic electrolytes was citric acid. The value of initial conductivity of electrolytes had the main influence on hydrogen peroxide formation. Electrolytes potassium dihydrogenphosphate and sodium sulphate the great influence on effectiveness and stability of the diaphragm discharge. Their rate constants reached maximum value by the application of solution with initial conductivity of approximately 400 mikrosiemens, particularly 0.0492 mmol/l.min and 0.048 mmol/l.min. On the contrary, low values of rate constant were achieved in electrolyte ammonium chloride at around the same initial conductivity – 0.0269 mmol/l.min. During experiments stainless steel and platinum electrodes were used. It was found that kind of electrode material hadn’t influence on generation of hydrogen peroxide. Hydrogen peroxide was formed only in the cathode space.
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Study on the influence of plasma activated water on seed germination
Vozár, Tomáš ; Zlámalová Gargošová, Helena (referee) ; Kozáková, Zdenka (advisor)
This bachelor thesis deals with study on the influence of plasma activated water on wheat seed germination. After interaction with the plasma, the water changes its composition and obtain new properties that are useful in agriculture. The theoretical part is divided into two parts. The first part of the theory is dealing with basic knowledge about plasma, its properties, and possibilities of plasma generation in laboratory conditions. In the second part, the work deals with plasma activated water – PAW. The preparation of plasma activated water is described in details as well as its physical-chemical properties and composition with respect to the PAW possible applications. The aim of the experimental part of this work was to prepare plasma activated water in three different plasma systems and apply it on wheat seeds. These three ways of activation used direct and indirect interaction of plasma with water surface. After the seeds were germinated, the influence of plasma activated water on seed germination and quality of crops was observed and compared to control samples. The influence of different ways of water activation was also evaluated. Results show positive effects of plasma activated water on the seed germination and it also increased the quality of crops. Next steps in this research should be the transfer of this experiment from the laboratory scale on the Petri dish to the pot experiments in soil.
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Diagnostics of plasma generated in water solutions and its application
Holíková, Lenka ; Brablec, Antonín (referee) ; Kozáková, Zdenka (advisor)
This thesis deals with the study of parameters of diaphragm discharge in liquids. NaCl solution of different conductivity was used as a conductive medium. Conductivities were adjusted in the range from 220 to 1000 µS cm-1. Two diagnostic methods were used for the study of plasma parameters. The first one was employed in the laboratory of plasma chemistry at Faculty of Chemistry, Brno University of Technology, namely the optical emission spectroscopy. The second method used for plasma diagnostics was the time resolved ICCD camera at the Laboratoire de Physique des Plasmas at the École Polytechnique in Paris. The reactor for the diagnostics by optical emission spectroscopy had the volume of 4 l, and it was made of polycarbonate. PET diaphragm was placed in the barrier separating the cathode and the anode space. Electrodes were made of titanium coated with platinum. Electric power source supplied a constant DC voltage of maximum 5 kV and electric current up to 300 mA. Spectrometer Jobin Yvon TRIAX 550 with CCD detector was used during the experiments in order to measure overview spectra within the range from 200 to 900 nm as well as OH molecular spectra and Hß line spectra. All spectra were scanned in both discharge polarities, i.e. at the cathode and the anode part of reactor. The basic parameters of the discharge plasma were calculated from the spectra, that means rotational and electron temperature and electron density. Another part of experiment consisted of measurements by the ICCD camera iStar 734. Two types of reactors were used. The first one was the same as the reactor for the measurements by the optical emission spectroscopy. The second one was also made of polycarbonate, but the volume of conductive solution was 110 ml, only. HV electrodes made of stainless steel were placed in this reactor. Ceramic diaphragm (Shapal-MTM) was used in both reactors. Diaphragms had different thickness and diameter of holes. ICCD camera acquired photographs with details of processes of the bubbles generation and discharge operation (propagation of plasma channels), depending on solution conductivity, dimensions of the diaphragm, and with respect to the electrode part of the reactor.
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Analysis of aromatic compounds in plasma treated onion
Krejsová, Lenka ; Kozáková, Zdenka (referee) ; Krčma, František (advisor)
This bachelor thesis deals with the analysis of fragrances in onions, which were exposed to plasma before planting. The adjustment was made to see if onion growth and yields would improve. The theoretical part deals with the quantitative and qualitative methods for the determination of volatile substances. It contains the principle and instrumentation of mass spectrometry as well as the tandem connection of gas chromatography with mass spectrometry. In the experimental part, a liquid sample was obtained by pressing. After 60 minutes, saturated vapors were analyzed by reactive ionization mass spectrometry (PTR-MS). Thanks to this analysis, the concentration of volatile substances was determined. Some samples were analyzed by gas chromatography with mass spectrometer as detector to identify the compounds, because PTR-MS does not allow distinguishing of isomers. Subsequently, the data were processed and evaluated. From the gathered obtained it is clear that the plasma treatment has an effect on the fragrances concentrations. After six months of storage, the presence of some volatile substances increased due to increased biological activity.
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Plasma activated water prepared by electrical discharge in liquids
Možíšová, Aneta ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
The aim of the diploma thesis is generation of active particles in plasma activated water (PAW) using a low-temperature plasma discharge. In this work I focus on the determination of hydrogen peroxide, nitrites and nitrates as active particles. The practical part is focused on a specific case of use of a plasma discharge in selected electrolytes dissolved in an aqueous solution. Here, three phosphates, differing in the number of acidic hydrogens, were selected for each experiment, and sodium chloride and tap water were compared for comparison. Phosphates were selected for their stable pH during plasma discharge in solution to monitor the effect of pH. The experiments were focused on investigating the stability of active particles in PAW, under which conditions is the highest production rate of these particles and what effect the pH value has on the result. It was found that hydrogen peroxide is generated the most in an alkaline environment but shows better stability in neutral. The concentration of generated nitrites is not high, but it shows stability, regardless of the polarity of the main electrode used for PAW generation. Nitrites were generated the most in alkaline environment and nitrates in acidic environment. One of the conclusions is that nitrates are not a very stable particle in PAW. Thanks to the activation and oxidation properties of plasma activated water, this method can be used in medicine or agriculture
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