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Polyhydroxybutyrate modification by grafting of functional groups
Melčová, Veronika ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
Presented bachelor thesis deals with a characterization of the effect of chemical grafting on thermal and mechanical properties of poly(3-hydroxybutyrate). Two grafting methods were chosen, chlorination and fluorination of PHB. The aim of the theoretical part of the work was to create a complete literature review containing basic information about polyhydroxybutyrate and the latest scientific evidence about possibilities of chemical modification of this polymer. The experimental part describes the chemical treatment of the material itself, as well as preparation of samples for testing and performing the selected analysis. Chemically grafted polymers were subjected to thermogravimetric analysis to determine their thermal stability. Thermal behavior of materials was studied by differential scanning calorimetry. Also non-isothermal crystallization of samples was observed in order to evaluate the influence of the grafted halogen atom onto the nucleation activity of the polymer. Selected samples were also subjected to dynamic mechanical analysis and tensile test.
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The Study of Polyolefins Photochloration
Kučera, Vladimír ; Tocháček, Jiří (referee) ; Petrůj, Jaroslav (advisor)
This Master´s thesis deals with heterogeneous photochlorination of polyolefins and especially with the photochlorination of polypropylene itself. In the theoretical part the available information about properties, manufactory and application of chlorinated polyolefins, specifically polyethylene and polypropylene, is provided. The basic principles of the photochemistry are described, which are further applied to the issue of photochemistry chain reactions and photochemical halogenations, mainly photochlorinations. The practical part includes design and realization of few types of equipment for the heterogeneous photochlorination of polypropylene done at low temperatures (to 50° C) by gaseous chlorine in bulk or chlorine suspended in suspension of PP in CCl4. Series of chlorination was accomplished, which was varied in the type of PP, in the way of dosage Cl2 and in the period of high pressure mercury lamp irradiation (1–90 minutes). The chlorine content in prepared samples was determined by the gravimetry with ATR-FTIR spectroscopy, as well as by the Shöniger combustion method. Their accuracies were than compared. The chlorine content dependence on the period of chlorination and on the porosity of initial PP was established.
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Assessment of the drinking water treatment plant effectiveness via ecotoxicological tests and screening analyses
Nývltová, Barbora ; Mravcová, Ludmila (referee) ; Zlámalová Gargošová, Helena (advisor)
The quality of raw water is deteriorating with the continuous increase in environmental pollution. Raw water is being modified to drinking water by technological processes, and it is therefore necessary to put increased demands on the efficiency of these technological processes and their possible innovation. Due to the fact that raw water is contaminated with different types of pollutants, it is necessary to continuously control the drinking water supplied to the public distribution network in order to ensure its quality. Drinking water treatment is still unable to treat the raw water perfectly, its pollution is only reduced to acceptable standards. For this reason, it is indispensable that the quality of drinking water is being checked regularly and at the same time the efficiency of individual technological processes of drinking water treatment is assessed. This includes screening analysis or eventually ecotoxicological tests. The thesis focuses on the efficiency of technological processes of drinking water treatment. Within the experimental part, samples of raw water and samples of water after each separation stage have been collected at the drinking water treatment plant in the Czech Republic. These samples have been subjected to ecotoxicological tests and screening analysis. Based on the ecotoxicological tests carried out on Thamnocephalus platyurus, Lemna minor and Vibrio fischeri, we can assume the emergence of harmful chlorinated by-products, resulting to nearly 100% mortality in T. platyurus. The results of the screening analysis carried out indicate, after the extraction of specimens by the SPE method using HPLC/MS, that the most effective method for the removal of hormonal substances is ozonization.
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Brominated and iodinated disinfection by-products
Bednář, Jiří ; Načeradská, Jana (advisor) ; Kopecká, Ivana (referee)
The reaction of a disinfectant with natural organic matter in the presence of bromides and iodides in raw water intended as a source of drinking water produces brominated (Br-DBPs) and iodinated disinfection by-products (I-DBPs) of water. These tend to be more cytotoxic and genotoxic than their chlorinated analogues. However, little information is available on these products compared to chlorinated ones. Therefore, the aim of this work was to provide an overview of natural and anthropogenic sources of bromine and iodine containing substances, to determine their influence on the formation of brominated and iodinated disinfection by-products, and to compare their cytotoxicity and genotoxicity with chlorinated products. Increasing seawater intrusion into the groundwater drinking water source was found to increase the concentrations of Br-DBPs and I-DBPs by up to thousands of percent. A number of substances can be released from water pipe material depending on the material. These include, for example, tenorite and copper cation released from copper piping, iron cation released from cast iron and steel piping, and bromides and dissolved organic carbon (DOC) released from plastic piping. All of these corrosion products contribute to increasing concentrations of DBPs in the distribution network. Both seawater and...
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Combination of different drinking water disinfection processes and their impact on the formation of disinfection by-products
Česká, Pavlína ; Načeradská, Jana (advisor) ; Fialová, Kateřina (referee)
Combining disinfection processes with chlorination can alter the formation and resulting spectrum of Disinfection By-Products (DBPs) in drinking water. While considerable attention has been given to DBPs formed during chlorination, DBPs formed during the application of multiple disinfection processes are a significantly less explored group. This study focuses on three most common disinfection combinations: chlorination-UV, UV-secondary chlorination, and ozonation-secondary chlorination. After chlorination, trihalomethanes (THMs) and haloacetic acids (HAAs) are the most commonly found DBPs in water. The resulting formation of DBPs is influenced by many factors. UV radiation at typical disinfection doses (40-186 mJ.cm-2 ) does not affect the formation of these two groups of compounds after treatment with UV radiation and secondary chlorination. During the advanced oxidation process (AOP) of chlorination-UV, generally more DBPs are formed than during chlorination alone. However, this can be partially minimized by adjusting the appropriate wavelength and pH of the treated water. For waters containing nitrogenous compounds or bromide, combining chlorination with UV radiation and chlorination with ozonation leads to higher formation of hazardous nitrogenous and brominated DBPs compared to chlorination...
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Disinfection by-products originating from pesticides
Plachá, Markéta ; Načeradská, Jana (advisor) ; Kopecká, Ivana (referee)
An important step in the treatment of drinking water is disinfection, which serves to remove pathogenic substances. During this process, disinfection by-products can be formed, which are mainly produced from organic natural substances reacting with the disinfectant. However, treated water may also contain anthropogenic substances, such as pesticides, whose disinfection by-products are the subject of this work. From the accessible data of the studies carried out so far, a basic summary of their creation was created, and characteristic properties that are essential for the evaluation of adverse effects on human health and the environment. From the field of organophosphorus pesticides, it was found that pesticides containing a phosphorothioate part can be easily oxidized by chlorine to the corresponding oxone derivative, while organophosphorus pesticides with a phosphate part are very stable in the presence of chlorine. The resulting oxon forms can be more effective inhibitors of acetylcholinesterase than their parent compounds and at the same time be stable enough (more than 24 h) to reach the consumer, on whom they can, however, have a negative effect. At the same time, disinfection by- products from pesticides can be more toxic than the original compounds. These include chloroxon, diazoxon and...
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Disinfection by-products in swimming pools and their effect on human health
Winterová, Sofie ; Načeradská, Jana (advisor) ; Barešová, Magdalena (referee)
Disinfection of swimming pool water is necessary for reducing the risk of disease transmission. Disinfection by-products form when chlorine reacts with organic matter contained in water. More than six hundred disinfection by-products have been found in swimming pools. Trihalomethanes, haloacetic acids, chloramines, halonitromethanes, haloacetonitriles and nitrosamines are among the most frequently occurring. Disinfection by-products may be toxic. The volatility of some of them causes their occurrence in the surrounding air and poses a risk not only for swimmers, but also for people in the vicinity who are not in direct contact with the water. DBPs enter human body by inhalation, absorption through the skin and ingestion. They have been linked to health problems such as skin and eye irritation, bladder cancer and respiratory diseases. Preventing their occurrence is not an easy task; a number of factors play a role in their genesis (the amount of organic matter, type and the amount of disinfection, the quality of source water, temperature, pH) and not all principles of their formation have been fully clarified yet. Further research on DBPs and their sufficient regulation are important steps to maintain chemical safety in swimming pools. Key words: disinfection by-products, swimming pool,...
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Assessment of the drinking water treatment plant effectiveness via ecotoxicological tests and screening analyses
Nývltová, Barbora ; Mravcová, Ludmila (referee) ; Zlámalová Gargošová, Helena (advisor)
The quality of raw water is deteriorating with the continuous increase in environmental pollution. Raw water is being modified to drinking water by technological processes, and it is therefore necessary to put increased demands on the efficiency of these technological processes and their possible innovation. Due to the fact that raw water is contaminated with different types of pollutants, it is necessary to continuously control the drinking water supplied to the public distribution network in order to ensure its quality. Drinking water treatment is still unable to treat the raw water perfectly, its pollution is only reduced to acceptable standards. For this reason, it is indispensable that the quality of drinking water is being checked regularly and at the same time the efficiency of individual technological processes of drinking water treatment is assessed. This includes screening analysis or eventually ecotoxicological tests. The thesis focuses on the efficiency of technological processes of drinking water treatment. Within the experimental part, samples of raw water and samples of water after each separation stage have been collected at the drinking water treatment plant in the Czech Republic. These samples have been subjected to ecotoxicological tests and screening analysis. Based on the ecotoxicological tests carried out on Thamnocephalus platyurus, Lemna minor and Vibrio fischeri, we can assume the emergence of harmful chlorinated by-products, resulting to nearly 100% mortality in T. platyurus. The results of the screening analysis carried out indicate, after the extraction of specimens by the SPE method using HPLC/MS, that the most effective method for the removal of hormonal substances is ozonization.
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Polyhydroxybutyrate modification by grafting of functional groups
Melčová, Veronika ; Tocháček, Jiří (referee) ; Přikryl, Radek (advisor)
Presented bachelor thesis deals with a characterization of the effect of chemical grafting on thermal and mechanical properties of poly(3-hydroxybutyrate). Two grafting methods were chosen, chlorination and fluorination of PHB. The aim of the theoretical part of the work was to create a complete literature review containing basic information about polyhydroxybutyrate and the latest scientific evidence about possibilities of chemical modification of this polymer. The experimental part describes the chemical treatment of the material itself, as well as preparation of samples for testing and performing the selected analysis. Chemically grafted polymers were subjected to thermogravimetric analysis to determine their thermal stability. Thermal behavior of materials was studied by differential scanning calorimetry. Also non-isothermal crystallization of samples was observed in order to evaluate the influence of the grafted halogen atom onto the nucleation activity of the polymer. Selected samples were also subjected to dynamic mechanical analysis and tensile test.
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The Study of Polyolefins Photochloration
Kučera, Vladimír ; Tocháček, Jiří (referee) ; Petrůj, Jaroslav (advisor)
This Master´s thesis deals with heterogeneous photochlorination of polyolefins and especially with the photochlorination of polypropylene itself. In the theoretical part the available information about properties, manufactory and application of chlorinated polyolefins, specifically polyethylene and polypropylene, is provided. The basic principles of the photochemistry are described, which are further applied to the issue of photochemistry chain reactions and photochemical halogenations, mainly photochlorinations. The practical part includes design and realization of few types of equipment for the heterogeneous photochlorination of polypropylene done at low temperatures (to 50° C) by gaseous chlorine in bulk or chlorine suspended in suspension of PP in CCl4. Series of chlorination was accomplished, which was varied in the type of PP, in the way of dosage Cl2 and in the period of high pressure mercury lamp irradiation (1–90 minutes). The chlorine content in prepared samples was determined by the gravimetry with ATR-FTIR spectroscopy, as well as by the Shöniger combustion method. Their accuracies were than compared. The chlorine content dependence on the period of chlorination and on the porosity of initial PP was established.
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