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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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Automated control of aquarium operation
Kejzlar, Radim ; Šteffan, Pavel (referee) ; Háze, Jiří (advisor)
This master´s thesis describes complete design and implementation of an automated system for the control of a common freshwater tropical aquarium with a keyboard and display. The thesis discusses the applicability of equipment in today's aquaristics of freshwater tropical aquariums with respect to the history and market offer. Thesis describes the complete design of the electrical, program and mechanical parts of the resulting system and electrically controllable automatic feeder, communicating with the system.
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Determination of selected nutritional parameters in the fruit of the plant genus Ribes
Ledvina, Vojtěch ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis focuses on the small fruit representatives from the plant genus Ribes L. - currant, gooseberry and jostaberry. The beginning of theoretical part describes history of cultivation and basic botanical description of individual cultivars. The next part describes important substances contained in fruit as well as their importance in human diet and it also describes some basic products made of the Ribes L. genus representatives. The final section of the theoretical part contains basic principal of determination of individual nutritional parameters. In the experimental part several nutritional parameters were determined including dry matter, soluble solids, pH, titratable acids, formol number, reducing sugars and total phenolics. Individual species and cultivars were compared based on the results.
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Determination of basic chemical characteristics of blackberry pulp
Pilátová, Anna ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with determination of selected chemical characteristics of juice, pulp and extract prepared from blackberry of two species, from The Czech Republic and Ukraine. The theoretical part contains the botanical characteristics of blackberry, the content of active substances and possibilities of use of blackberries in the food industry. The following chapters focus on the description of phenolic substances and the determination of pH and titration acidity of fruit juices by manual methods. In the experimental part, two extraction solvents were first compared for extraction of anthocyanins from blackberry moldings. Furthermore, the selected chemical and physical properties of extracts, juice and pulp from blackberries were determined. The analysis was carried out for blackberries from the Czech Republic and Ukraine. A 1 : 1 mixture of distilled water and ethanol was a better extraction solvent for the content of anthocyanins. After 14 hours of maceration 150.4 mg of anthocyanins was obtained from 100,0 g of blackberry moldings Extract from blackberry moldings has been determined to have a much higher concentration of anthocyanins than juice and pulp. The extract of Ukrainian blackberries contained 197.4 mg CGEdm-3 and extract of Czech blackberries 150.4 mg CGEdm-3. Also phenolic substances had the highest concentration in extracts. Ukrainian blackberries contained 3501.9 mg GAEdm-3 and Czech blackberries contained 3256.1 mg GAEdm-3.
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Influence of pH on Extraction of Matter from Biochar-Soil Complex
Jakubčeková, Kristína ; Enev, Vojtěch (referee) ; Kalina, Michal (advisor)
Biochar is one of the possible solutions to improve the soil fertility, therefore it is necessary to investigate both its composition and the impact on the soil under various conditions. The aim of this bachelor thesis is to focus on the description of the influence of pH on the amount and type of substances (molecules, ions) that are leached from the biochar into the soil and thus consequently influence its properties. As a soil model it was chosen cambisol which is the most widespread soil in the Czech Republic. The selected pH values have been defined in such a way to cover the pH range that is common for various soil types in natural conditions. In the experimental part of this thesis the extracts from the used sample of biochar and soil were characterized first. These characteristics obtained in this way were subsequently compared with the data obtained for the biochar-soil complex extracts that was obtained after a defined period of cultivation of the mixture. For the characterization of extracts the basic physico-chemical methods (pH, conductivity, elemental and thermogravimetric analysis, UV-VIS) and also the analysis of leached ions and molecules by means of ICP/OES, GC-MS were used. Evaluated experimental data show that under the condition of cultivation experiments, the influence of biochar was observed only on the basic physico-chemical characteristics of the soil (mainly pH). On the other hand, there was no significant tendency of the impact of biochar on the representation of selected elements and on the content of organic matter in the soil. Long-term biochar-soil cultivation experiments could be a suitable solution.
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Flow Measurement Using Dilution Methods
Pokorný, Pavel ; Jiřík, Radovan (referee) ; Harabiš, Vratislav (advisor)
The bachelor thesis focuses on the construction of a program in LabVIEW to measure pH with the Vernier sensing probe connected through the interface LabPro and to be able to inset the measured data with a physical model of a dilution curve to get information about the model. It further describes the necessary requirements of the product in which the measurement of the dilution curve would be possible, the principle of constructing it and its usage with the above mentioned program to construct a laboratory task.
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The application of chlorine for public swimming pool water disinfection
Wagnerová, Andrea ; Svoboda, František (referee) ; Biela, Renata (advisor)
The bachelor thesis focuses on issues surrounding disinfectants of swimming pool water. The dissertation examines various chlorine based disinfectants as well as chlorine free disinfectants. Part of the thesis compares advantages and disadvantages of different possibilities of securing hygienic swimming pool water. Several complexes of public swimming pools in Brno and its neighbourhood were visited in order to examine the methods of disinfection, which are currently used at those swimming pools. Disinfectants based on chlorine are currently used the most for swimming pool water.
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Investigation of yeast properties during the beer fermentation
Kociánová, Lenka ; Vítová, Eva (referee) ; Omelková, Jiřina (advisor)
In this diploma thesis, the properities of brewery’s yeasts during the operation beer fermentation in the selected brewery and dependences of diferent agents and their influence on viability and vitality of the yeasts were studied. Other observed properities were physiological state, pH, temperature, a value of soft and coarse sludges, a value of dissolved oxygen in wort, the level of wort’s fermentation. It were collected the samples of fermenting wort and washing yeasts for determination. The used yeasts were observed from the first time until thein last used (generally 4 times). pH, temperature, apparent fermenting and total numer of yeast cells were measured in the collected samples. The used yeasts were washed before every other application and vitality was determined. The number of death cells were observed by this method. The number of death cells never fell bellow 5 %. The value of dissolved oxygen in wort is also the important agent for the growth of yeasts. The touchs with low number of oxygen showed that the time for fermentation had to be longer (by about 3 or 4 days more). The touchs with higher number of sludges showed that the sludges haven’t any influence on the yeasts and the procces of fermentation. Confirm the accuracy of the repeated used of the yeasts was the object of this thesis.
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Selected nutritional parameters of some lesser known fruit
Diblíková, Michaela ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
Diploma thesis is focused on the chemical analysis of the juices of black, red and white currant and jostaberry (Ribes a Ribes x culverwellii). The theoretical part is focused to the definition of fruit, fruit importance in human nutrition, description of Ribes and Ribes x culverwellii genuses, active substances in the currants and the jostaberry, description of selected chemical parameters and the determination of some of them. The procedures of determining for the following chemical parameters are described in the experimental section: determination of reducing sugars, determination of total and soluble solids, formol number, pH, titratable acidity, determination of total phenols and anthocyanins and determination of vitamin C in two samples jostaberry, six varieties of black currants, one variety of white currant and two varieties of red currants. Based on the evaluation of the obtained results, the comparison was made with different varieties and the thesis that "overall comparison of the different varieties in the content of phenolic compounds, vitamin C and anthocyanins appears to be the most promising variety of blackcurrant demon. It should however be noted that the highest content of phenolics and anthocyanins were determined in jostaberry„ has been suggested.
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The influence of detergents on time to failure of high density polyethylene by full notch creep test performed in corrosive bath
Kotoučková, Simona ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
The thesis deals with the study of the influence of concentration and different types of surfactants (Igepal CO-520, Arkopal N110, Igepal CO-890, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, dodecyltrimethylammonium bromide and Dehyton PL) on the environmental stress cracking resistance of high-density polyethylene by means of Full Notch Creep Test. Furthermore, the influence of ligamental stress (3,5; 4,0 a 4,5 MPa), pH of the prepared active environment and type of the water used as a solvent for the surfactants on the time to failure was monitored. An accelerating effect was observed at increased concentration, stress and molecular weight. Faster failure was achieved after exposure to ionic types compared to nonionic. The rate of the notch opening was determined. The brittle and ductile behavior during the process of failure was evaluated by microscopic analysis of the morphology of the fracture surfaces. Based on the pH change after the test, the stability of the active environment was evaluated. Deteriorating quality of surfactant solutions was observed. Raman spectroscopy and Fourier transform infrared spectroscopy were used to detect the surfactant on the surface of the test specimen after the test.
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