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Preparation and characterization of plasma activated water
Lemonová, Hana ; Klímová, Edita (referee) ; Krčma, František (advisor)
This bachelor thesis deals with suitable methods for plasma activated water preparation. The plasma activated water is a new way of the indirect plasma application for the treatment of biological materials like food or even for the direct application for therapeutic purposes. The theoretical part is focused on getting acquainted with plasma activated water and methods for its preparation, using various plasma systems. The detailed description of the plasma-liquid systems used during this thesis is given later. The selected physical chemical properties, namely conductivity, pH value and stability of hydrogen peroxide are presented in the results part. An important aspect of this work was to find suitable storage conditions for plasma activated water.
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Design of Hydrogen Peroxide Disinfector
Makarová, Sylvia ; Rubínová, Dana (referee) ; Fridrichová, Eva (advisor)
The aim of this bachelor thesis is to design a hydrogen peroxide disinfector with regard to all its functional and technical parameters. Emphasis is placed simultaneously on the aesthetics of the product. The work is based on the analysis of accesible products and detailed technical analysis. The final device is intended primarily for medical facilities, but it can be used in any other areas, where is disinfection needed
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Plasma diagnostics of electric discharges generated in selected configurations in liquids
Vašíček, Michal ; Bartlová, Milada (referee) ; Kozáková, Zdenka (advisor)
My diploma thesis is focused on a comparison of direct-current and high frequency (15-80 kHz) electric discharge, which generates non-thermal plasma in water solution of sodium chloride. Mainly current-voltage and Lissajous charts are discussed in the first part of this thesis. These charts describe different discharge phases: electrolysis, bubble formation, discharge breakdown and discharge regular operation in a pin-hole of a dielectric barrier. Influence of frequency, electrolyte conductivity, thickness of the diaphragm (or length of the capillary) and pin-hole diameter on discharge breakdown and bubble generation was studied, too. Measurements were realized in a polycarbonate reactor with total volume of 110 ml, which was divided by a changeable polyacetal insulating wall. This wall divided the reactor into two approximately equal spaces with one stainless steel planar electrode in each part. The Shapal-MTM ceramic discs (thickness of 0.3–1.5 mm and diameter of the central pin-hole of 0.3-0.9 mm) were mounted in the centre of the insulating wall. Initial conductivity of sodium chloride solution was chosen within the interval of 100900 S/cm. The second part of my thesis compares an influence of the direct-current (DC) and high frequency (HF) power sources on physical solution properties (conductivity, pH and temperature) and generation of hydrogen peroxide. A plasma reactor with total volume of 4 l and with mixing set up was divided into two equal spaces with one planar platinum electrode in each part. Diaphragm with thickness of 0.6 mm and pin-hole diameter of 0.6 mm was installed in the middle of the separating wall. Experiment was held at discharge operation of 45 W for 40 minutes with both power sources. Detection of hydrogen peroxide was realised by using a titanium reagent forming a yellow complex, which was analysed by absorption spectroscopy. If HF discharge power is plotted as a function of applied frequency, exponential decrease of frequency with increasing power can be observed. Higher breakdown voltage is necessary for thicker dielectric barriers, on the other hand for bigger diameter of the pin-hole lower breakdown voltage and higher power is needed in DC as well as in HF regime. Breakdown voltage is decreased by the increasing conductivity in both regimes; due to more charge carriers in the higher conductivity lower breakdown voltage is needed. However frequency in HF regime and DC discharge power increases. HF discharge power is decreased by the increasing conductivity. Solution conductivity and temperature are increased by initial conductivity value in both discharge regimes. Solution pH drops to acidic conditions when HF or DC positive regime is applied due to the generation of reactive species and electrolysis (in DC regime). However solution becomes alkaline when DC negative regime is applied. Concentration of hydrogen peroxide is produced linearly when HF or DC negative regime is applied and it depends on initial solution conductivity.
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Separation efficiency of water pollutants on pilot plant photoreactor
Melicher, Daniel ; Mirko,, Dohnal, (referee) ; Svěrák, Tomáš (advisor)
The thesis deals with photocatalysis of organic pollutants on UV-activated anatase particles, on UV-activated anatase particles with hydrogen peroxide and hydrogen peroxide itself. The measurement is carried out on a pilot plant UV photoreactor. The aim of the thesis is to determine the effectiveness of azo dyes and antibiotics degradation. The level of azo dyes and antibiotics degradation is measured by UV-VIS spectrometry.
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Electric discharges in water and organic solutions
Klímová, Edita ; Brablec, Antonín (referee) ; Kozáková, Zdenka (advisor)
This work is focused on study of electrical discharges in liquids, especially in water solutions. Generation of the discharge in water solutions leads to simultaneous effect of UV radiation, shock waves, electrical field and most importantly, chemically reactive species. This can be utilized in many applications such as sterilization, degradation of organic waste products, lithotripsy or other medical applications. The experimental part is concentrated on a diaphragm arrangement of the reaction system. This means that the reactor is divided into two electrode reservoirs connected only through a small orifice in a dielectric barrier. This barrier is made of Macor® non-porous ceramics with thickness of 1 mm, with the diameter of the orifice 0.6 mm, in the first part of work. In the second part, ShapalTM-M ceramics of thickness 1.0 mm and orifice diameter 0.6 mm was used. The experimental part is divided into two sections. For both, NaCl is chosen as an electrolyte to set the initial conductivity of the tested solutions to the value of 400 S/cm. Supplied direct voltage is regulated to attain power of 100 W in the system. In the first part, effect of addition of chosen alcohols (ethanol, isopropylalcohol and glycerol) on the efficiency of the discharge in their water solutions is studied. For this purpose, a special glass reactor was designed and constructed. The efficiency of the discharge is measured by a spectroscopic determination of concentration of complex formed by a titanium reagent and hydrogen peroxide, which is generated during the discharge. The results show no positive effect of addition of extra OH group to the reaction through the alcohols. The use of isopropylalcohol causes even a significant decrease in the amount of hydrogen peroxide generated. The subject of the second part is a comparison of effect of different electrode materials on the discharge. The efficiency is measured by the same method as in the first part. Materials chosen were stainless steel, platinum, aluminium, copper and carbon. Each material shows different hydrogen peroxide production rate under the same parameters. The most perspective material seems to be carbon, as an inert material, that can be expected not to initiate any decomposition of hydrogen peroxide. The least favourable appears to be copper. When used, no production of hydrogen peroxide was observed in one of the electrode parts of the reactor.
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Spectrophotometry of ROS species with focus on hydrogen peroxide
Zhorný, Lukáš ; Hořavová, Lenka (referee) ; Provazník, Ivo (advisor)
The main theme of this work is spectrophotometry. The first chapter describes the theoretical problems of the topic, relevant units and formulas for calculating the absorbance of the solutions of given concentrations. Further disclosed herein is a spectrophotometer, its individual parts, and the principle on which the unit is based. The last chapter of the theoretical introduction to this work is focused on the production of ROS in living organisms and especially in plants, and then there are some spectrophotometric methods for determining the concentration of ROS. The practical part describes the method using TiCl4 and method using KI. Both methods were used to determine the hydrogen peroxide concentration and subsequent measurement of absorbance of solutions of standard hydrogen peroxide added interfering substances. Then, the statistical analysis of the measured data and the assessment of the impact of these interferents to measure absorbance. The first of these methods proved to be suitable for a given measurement.
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Study of decontamination effects of plasma and plasma activated water
Kovaříková, Kateřina ; Krouská, Jitka (referee) ; Kozáková, Zdenka (advisor)
The theoretical part of this Diploma’s thesis describes the use of plasma in decontamination processes. The experimental part of the thesis focuses on the preparation and characterization of model samples of organic dyes by appropriate analytical methods. The model samples were treated by direct exposure to plasma or plasma activated water. For both treatments, two different plasma sources were used - a dielectric barrier discharge in an ozonizer with subsequent bubbling of its gaseous products into the solution, and a microwave plasma jet applied to the liquid surface. The aim of the work was to evaluate the decontamination rate of the samples and to compare the performance of the different systems.
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Removal of organic pollution using advanced oxidation processes
Přibilová, Petra ; Kučerík, Jiří (referee) ; Chýlková, Jaromíra (referee) ; Opatřilová, Radka (advisor)
The presented doctoral thesis deals with the use of advanced oxidation processes combining hydrodynamic cavitation (HC) to produce hydroxyl and sulfur-based radicals. The investigated micropollutants are selected natural estrogens estrone (E1), 17-estradiol (E2), estriol (E3) and synthetic 17-ethinylestradiol (EE2). The theoretical section includes information on the properties of estrogens, their occurrence and effects in the environment on non-target organisms across trophic levels; and list of options for their removal from wastewater. The advanced oxidation processes themselves are also discussed and current knowledge in this area is summarised. In the research section, used analytical methods (LC-MS/MS and spectrophotometry), designs of individual experiments and results of tested processes are described. In addition monitoring the efficiency of different combinations of hydrodynamic cavitation and other agent and the suitability of the materials used on the experimental unit were also investigated. The sorption/desorption onto the surface of selected plastic materials (SBR, EPDM, PTFE, Tygon S3TM, PVDF and PVC) was also evaluated. Based on the results, the material for the unit - on which the degradation experiments were carried out - was selected. The methods chosen for the removal of estrogens from water were HC/H2 O2 , HC/O3, HC/percarbonate, HC/persulfate, hydrodynamic cavitation alone, and H2O2 alone. The design of the experiments was created to minimize the time required to treat the water, ideally one cycle per unit (4 seconds), which corresponds to the flow-through arrangement of the system.
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Comparison of plasma activated water quality prepared by different plasma systems
Staškovanová, Denisa ; Krčma, František (referee) ; Kozáková, Zdenka (advisor)
This diploma thesis deals with generation of reactive species (hydrogen peroxide, nitrates, nitrites) using various plasma systems in distilled and tap water. Prepared plasma activated water differs in the way the plasma is applied, namely plasma above the water surface, plasma inside water or bubbling of plasma gaseous products into water. The main goal is to determine the amount of species produced in different plasma systems and compare them with each other. The effect of ozonizer experimental conditions on the generated amount of reactive species is also monitored.
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Use of stress factors for the production of lipid substances by yeasts of the genus Metschnikowia
Tručková, Marie ; Márová, Ivana (referee) ; Němcová, Andrea (advisor)
This Master´s thesis consists of two parts. The theoretical part is focused on the influence of various stress factors in the cultivation process, such as osmotic stress, oxidative stress, dehydration, cultivation time, pH or temperature on yeasts of the Metschnikowia genus. The practical part deals with osmotic and oxidative stress. Oxidative stress was performed under two different conditions (various cultivation time and temperature). The properties of yeast production were monitored mainly by gas chromatography and marginally also by flow cytometry. The analysis was performed for Metschnikowia pulcherrima, Metschnikowia andauensis, Metschnikowia chrysoperlae, Metschnikowia sinensis, Metschnikowia zizyphicola and Metschnikowia shanxiensis strains. The results showed that both oxidative stress and osmotic stress induce better lipids production. The amount of lipids, especially the fatty acid composition, also varied depending on the strains studied and the culture conditions used. The production of unsaturated fatty acids was further demonstrated in this work. The most suitable medium for the production of lipids and unsaturated fatty acids was the salt medium. It is clear that yeasts of the genus Metschnikowia are highly adaptable yeasts. Therefore, they might be potentially auspicious biotechnology producers.
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