|
|
Study of ozone reactions with the surface of metallic materials
Krzyžanková, Anežka ; Kozáková, Zdenka (referee) ; Mazánková, Věra (advisor)
This bachelor thesis is focused on the study of ozone and oxygen reactions with the surface of metallic materials. Ozone undergoes spontaneous decomposition, which is, for example, influenced by increased temperature or reactions with other substances. The aim is to find out how fast heterogeneous decomposition or ozone formation takes place on different metal surfaces. The theoretical part describes the properties of ozone, possibilities of its use, generation of ozone, methods of determination of concentration and relation of ozone to solid surfaces. The experimental part examines how the ozone concentration changes depending on the reaction time at room temperature, the change in oxygen and argon flow during blowing, and the decomposition itself on the steel, copper, and aluminum surfaces. The ozone generated from the oxygen was enclosed in a metal material tube and allowed to react for a certain period of time. After this time, the ozone was blown out by various oxygen flow rates. Ozone concentration was monitored by absorption spectrometry. The dependence obtained shows that ozone concentration decreases. In further experiments, ozone was allowed to flow through the tubes for 5 min. After this time, pure oxygen was fed into the tube and ozone formed by heterogeneous surface reactions. The influence of the reaction time on the formation and disappearance of ozone on the surfaces was investigated. Finally, surface analysis was performed using a scanning electron microscope with elemental analysis.
|
|
|
Ozone gas-fading of photographs
Védlová, Petra ; Kozáková, Zdenka (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with principels of inkjet printing, ink composition and print media. The paper also focuses on stability of inkjet prints, degradation of inks by ambient impacts, mechanisms of such degradations and protection against degradation. The experimental section examines the impact of ozone on gas-fading of injekt prints, which is one of the most important factors by degradation of dyes for both clasic prints and prints with protective varnish. In conclusion two methods for assessing dye degradation – colorimetric (by calculating the volume of the color gamut) and densitometric (by calculating optical densities) – are investigated and compared.
|
|
|
Design of Universal Equipment for Tire Cutting
Kohoutek, Petr ; Veselý, Oldřich (referee) ; Prokeš, František (advisor)
The main content of of this thesis is a construction design and analysis of a machine for cutting tires. The resulting solution emerges from the design options and the option that meets the best selection criteria is chosen. Then the thesis stops for a while at the choice of cutting technology and tries to exemine its suitability for cutting tires. In its other part there is an attempt to clarify the relevant parts of the machine, where the benefits of three-dimensional views is used. Basic design and check calculations are done in the selected machine parts.
|
|
|
Study of oxygen and ozone reactions on the surface of construction materials
Krzyžanková, Anežka ; Brablec,, Antonín (referee) ; Mazánková, Věra (advisor)
This master's thesis deals with the study of the reactions of the ozone and oxygen with various construction materials. Ozone as an unstable gas tends to decompose spontaneously and this process can be accelerated by reaction with other substances. The aim of this work is to determine the course of ozone's formation and its depletion in after the contact with various substances. Ozone is widely used mainly due to its disinfecting effects. Therefore, the monitoring of these reactions is beneficial for the choosing of ozonizer's material or its accessories. The theoretical part of this work describes the important properties of the ozone, the possibilities of using this gas, various methods of its generation, the influence of gas admixtures and a temperature on its generation and decomposition, the methods of determining the concentration and surface reaction. The dependence of ozone's formation on the size of the reaction space was monitored for either the silicone and Teflon material in the experimental part of the thesis. The length of the hoses was 20-50 cm and the diameter of the inner space was 6 mm for Teflon and 7,99 mm for a silicone. Furthermore, other experiments were performed for the silicone material, where the formation of the ozone was monitored while the oxygen and argon were being used as working gases. The formation and the depletion of the ozone depending on the changes of reaction time were investigated in the third series of experiments. We worked with a ceramic material with two different inner diameters and also with a brass and a stainless steel material in this experiment. The materials were constructed as the tubes of the same length of 54 cm. The ozone generated from the oxygen was enclosed into the reaction tube and the depletion was monitored. The last experiment was focused on the monitoring of the course of ozone's formation in a quartz cuvette influenced by the reaction time and the composition of the working gas. The amount of generated ozone was determined by absorption spectrometry in the all studied cases. The ozone flowing through the system was adsorbed by the surface of the material during the discharge. A mixture of gases (the adsorbed ozone, the oxygen and the argon in various ratios) was present in the sealed reaction space. The Ozone was formed on the surface of the material. The adsorbed ozone decomposed into a molecular and an atomic oxygen. The atomic oxygen reacted with the oxygen molecule occurring in the reaction space. The reaction time leading to the biggest obtained concentration of generated ozone was determined by the experimental data. For most of the materials, the reaction time was about 6 minutes.
|
|
|
Characterization of plasma activated water for biomedical applications
Šindelková, Kateřina ; Dzik, Petr (referee) ; Kozáková, Zdenka (advisor)
The aim of this master thesis is to characterize plasma activated water (PAW) prepared in various plasma systems using direct and indirect interaction of plasma with liquid or its surface. Plasma was generated by electric discharges at atmospheric pressure. The prepared plasma-activated water was studied with respect to its use in biomedical applications. The theoretical part deals with plasma activated water. It contains a description of the PAW preparation, its characterization in terms of produced particles or its physico-chemical properties. Also, methods for antimicrobial activity estimation or colorimetric determination of produced particles are described in this section. In the experimental part of this work, the types of discharges that were used for the PAW preparation and their comparison are presented. Two types of liquids were selected for the activation, namely distilled and tap water. Subsequently, concentrations of selected reactive particles in PAW (hydrogen peroxide, nitrates and nitrites) produced in three different plasma systems were determined. Besides the comparison of reactive particles production in various systems, their time stability was studied as well. Over time after the PAW preparation, the values of active particles concentrations have changed due to mutual interactions between the particles. Mainly, nitrites were oxidized to nitrates or vice versa depending on the PAW type and other conditions. Part of the work was also monitoring selected physical properties of PAW, namely pH value and specific conductivity. It has been found that PAW does not retain its activated properties for too long, depending on the type of preparation and methods of storage. Therefore, one of the important goals of this work was to determine and compare suitable storage conditions for PAW with respect to its potential biomedical applications.
|
|
|
Study of ozone decomposition on solid surfaces
Krejsková, Eliška ; Stančík, Jiří (referee) ; Kozáková, Zdenka (advisor)
This bachelor’s thesis is focused on the study of ozone decomposition which occurs during its contact with solid surfaces. The aim is to find out which material causes the lowest ozone decomposition and that is why it is the most suitable material for pipelines used for ozone transportation from a place of production to a place of application. In the theoretical part important properties of ozone, possibilities of its production, methods of ozone determination and relation of ozone to different solid surfaces were described. In the experimental part there was investigated how much ozone is decomposed by five commonly available metal materials (stainless steel, yellow brass, copper, aluminium and iron). Measurements were realized in the glass tube (Liebig condenser). Hollow pipes made of particular material were inserted into this tube. Ozone passed through this glass tube and ozone concentration was determined on its output by two methods: the iodometric titration and spectrophotometry. Several series were measured and compared by different set-up conditions like reaction time, experimental parameters (flow rate of air, input power of the ozone generator) and two types of gas – technical and synthetic air (because moisture contained in technical air can cause ozone decomposition) were used. The most suitable materials – stainless steel and aluminium were determined according to gained results.
|
|
|
Options hygiene of drinking water
Šopíková, Lucie ; Hlaváč,, Jaroslav (referee) ; Biela, Renata (advisor)
The first part my Graduate work contains an overview of all possible types of disinfection of drinking water used in the present. The second part shows examples of use of each mentioned type of drinking water disinfection methods, which can be found in practice, that is on water treatment plants. The conclusion is a comparison of advantages and disadvantages of various methods of disinfection.
|
|
|
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.
|
|
|
Use of oxidation processes (AOP) for removal of micropolutants
Stříteský, Luboš ; Pešoutová,, Radka (referee) ; Hlavínek, Petr (advisor)
This thesis deals with advanced oxidation processes (AOPs) and it’s use for removal of micropollutants from wastewater. The first chapter explains the need AOPs, water quality, pollution and substances that are present in the water. Further, the first chapter outlines approach of the current legislation to micropollutants. The second chapter explains the theory and principle of operation of AOPs. This chapter is divided into two sections. The first section describes AOPs, which were tested at selected WWTP. In the second section, there are described some other AOPs. The third chapter is a literature retrieval of AOPs dealing with the removal of micropollutants. This chapter is focused on the removal of hormones by AOPs using ozone-based AOPs. The fourth chapter describes the actual testing of selected AOPs. The chapter describes selected WWTP, pilot-scale AOP unit and test results. In the last chapter there is designed and described full-scale AOP tertiary unit for removing of micropollutants. The last chapter also contains economic analysis of the proposed tertiary unit.
|
|
|
Material printing of ozone dosimeters
Petříčková, Zuzana ; Čeppan,, Michal (referee) ; Veselý, Michal (advisor)
This study presents various methods of measuring ozone and consolidates current state of knowledge in the field of disposable printed ozone dosimeters. The paper also identifies prospective dyes for preparation of ozone dosimeters available on the market. Information gathered from literature review was used to prepare dosimeters based on two different dyes. These were calibrated for screen printing technology and their sensitivity to ozone was optimized to achieve visual detectability. Prepared samples were observed and studied while being exposed to ozone. Then, long term mechanical and chemical properties of these were tested in order to identify appropriate conditions for storage.
|
guest ::
