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Analysis of humic acids solutions after their decomposition by diaphragm discharge
Totová, Ivana ; Švejdová, Dana (referee) ; Kozáková, Zdenka (advisor)
Preliminary results of research focused on the applications of DC diaphragm discharge in water solutions containing humic substances are presented in this diploma thesis. Electrical discharges in water produce various reactive species such as radicals (•OH, •O, •H), ions and molecules (H2O2, O3). These species have high oxidation potential and thus they easily react with order species and molecules. Such reactions could lead, for example, to destruction of organic pollutants dissolved in water. This work studies this effect on humic matters that can be contained in water coming from floods. Diaphragm discharge investigated by this work was created in the reactor using konstant DC high voltage up to 2 kV that gave the total input power from 100 to 200 W. Breakdown and discharge ignition started in the pin-hole in the dielectric barrier separating two electrode spaces (anode and cathode space). Presented work investigates decomposition of humic substances by the electric discharge in the dependence of solution properties and discharge conditions. Parameters such as initial solution conductivity, electrolyte kind or input power have been investigated. Moreover, substantial effect of pH on humic acid decomposition has been observed. Refraktometry and absorption spectroscopy in UV-VIS region together with fluorescence spectroscopy has been used for the detection of changes in humic solutions.
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Influence of soil management on properties of humic substances
Rubínková, Eva ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The aim of the Diploma thesis is to consider an influence of soil management (rotation of crops on arable land and grassland) to quantity and quality of humic substances. These properties are depended not only upon way of soil management, but also upon climatic effects, such are rainfall, temperature, elevation above sea-level, level of underground water and content of clay. Significantly influenced factors are content and form of organic carbon which is very tightly bonded to humic substances. In this work the humic acids content and properties progression was studied in given time period. Also the effect of crop rotations to changes of physical and chemical properties of humic acids in soil environment was observed. Diploma thesis was realized in co-operation with Mendel University in Brno, which supplied elaborating samples. Studied soil samples were taken from humus horizon Cambisol modal Vatín during years 1999–2006, always in autumn. Individual samples were characterized by available analytical methods, which are generally used in humic substances research area. They are especially fluorescence spectrometry, UV-VIS and infrared spectrometry and acid-base and conductometric titrations.
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Fluorescence probes for immobilized photocatalyst activity monitoring
Blašková, Martina ; Dvoranová, Dana (referee) ; Dzik, Petr (advisor)
This diploma thesis deals with the use of fluorescent probes for evaluation of photocatalytic activity of immobilized photocatalyst. To the evaluation of photocatalytic activity of TiO2 were used three different fluorescent probes – terephthalic acid, coumarin and benzoic acid, wherein was monitored the increasing intensity of fluorescence of their oxidation products – hydroxyterephthalic acid, 7-hydroxycoumarin and salicylic acid for the photochemical degradation of various fluorescent probes. To the evaluation of photocatalytic activity was used solid phase (photocatalyst) – liquid phase (probe) system and was used three sources of radiation. Fluorescence of oxidation products was monitored by the fiber spectrometer and a conventional cuvette fluorometer.
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Analýza džusov metódou „UV-odtlačkov prstov”
Saganová, Sabrina
Nowadays, people's interest in healthy food is increasing. These are mainly food ingredients as much as possible in their natural form. Such foods also include fruit juices, which, in addition to quenching thirst, also contain substances beneficial to health - vitamins, minerals, carbohydrates, proteins and others. By taking fruit juice, we support the immune system, intestinal peristalsis, strengthen bones, and even consumption of fruit can serve as a means of preventing cancer. However, with the increase in the consumption of fruit juices (especially orange and apple), the risk of adulteration of these drinks also increases. It is precisely in this context that it is ne-cessary to constantly look for new and fast methods with which to guarantee the quali-ty and safety of food. In the first part of this thesis, I focused on the composition of fruit juices, their health benefits for the human body, production, methods of counter-feiting. The second part of this work consists of a study in which the new method of "UV-fingerprints" was used as a quick tool for verifying the quality of fruit juices. The method is based on the spectral properties of the sample before and after irradiation with high-energy ultraviolet radiation (λ = 254 nm). During the irradiation, photoche-mical changes will occur, which serve to identify the sample. I optimized the method by placing the samples in different temperature environments (laboratory temperature, refrigerator, freezer). Subsequently, using boxplots - statistical evaluation, I tried to find differences both within individual types of fruit, but also between individual brands of one type of fruit.
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Program-controlled freeze drying for the preparation of the drug-delivery system based on polysaccharide and hydrophobic molecules
Dufková, Michaela ; Kalina, Michal (referee) ; Enev, Vojtěch (advisor)
The lyophilization process favors the hydrophobic effect between the individual dextran chains. This hydrophobic effect allows hydrophobic drugs to settle and remain within the biopolymer. Due to hydrophobic effect, dextran can serve as a carrier for the distribution of hydrophobic drugs. The goal of this thesis was to prepare a carrier system based on native dextran using program-controlled freeze-drying. Hydrophobic drugs were modeled using the fluorescent probes pyrene and prodane. The effectiveness of promoting the hydrophobic effect was studied using infrared spectrometry, fluorescence spectrometry and scanning electron microscopy. Using ATR-FTIR spectrometry, a shift of the absorption band of thevalence vibration of the C–O bond in OH groups in alcohol was observed. Using fluorescence spectrometry, the emission polarity index was calculated for pyrene from the 1st and 3rd maximum fluorescence intensity, and for prodan, a shift of the maximum fluorescence intensity to lower wavelengths was observed. SEM images showed that during the lyophilization process, the dextran structure formed a dense network of fibers, indicating the presence of many sites with a higher content of hydrophobic domains. Positive results were obtained with these methods, which proved the positive effect of lyophilization on the formation of a hydrophobic effect between individual polysaccharide chains. The results may contribute to the development of carrier systems for hydrophobic drugs.
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Characterization of upconversion nanoparticles by fluorescence spectrometry and capillary electrophoresis
Vaněčková, T. ; Zítka, J. ; Hlaváček, Antonín ; Adam, V. ; Vaculovičová, M.
Upconversion nanoparticles (UCNPs) are a novel class of luminescent tags for applications in life and material sciences. Unlike traditional fluorophores, UCNPs exhibit emission of shorter wavelength under near-infrared excitation (typically 980 nm). In this work, we have examined these unique photophysical properties by fluorescence spectrometry and capillary electrophoresis. UCNPs co-doped with Yb(III) and Er(III) were characterized using laboratory-made fluorescence spectrometer. We have exploited and evaluated two excitation sources and the dependence of the fluorescence of UCNPs on the relative excitation power. Moreover, capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection was for the first time used for characterization of the nanoparticles. It was proved that CE-LIF is a valuable method to be used for investigation of upconversion luminiscence and monitoring of the interactions of UCNPs with other molecules of interest.
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Fluorescence probes for immobilized photocatalyst activity monitoring
Blašková, Martina ; Dvoranová, Dana (referee) ; Dzik, Petr (advisor)
This diploma thesis deals with the use of fluorescent probes for evaluation of photocatalytic activity of immobilized photocatalyst. To the evaluation of photocatalytic activity of TiO2 were used three different fluorescent probes – terephthalic acid, coumarin and benzoic acid, wherein was monitored the increasing intensity of fluorescence of their oxidation products – hydroxyterephthalic acid, 7-hydroxycoumarin and salicylic acid for the photochemical degradation of various fluorescent probes. To the evaluation of photocatalytic activity was used solid phase (photocatalyst) – liquid phase (probe) system and was used three sources of radiation. Fluorescence of oxidation products was monitored by the fiber spectrometer and a conventional cuvette fluorometer.
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Influence of soil management on properties of humic substances
Rubínková, Eva ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The aim of the Diploma thesis is to consider an influence of soil management (rotation of crops on arable land and grassland) to quantity and quality of humic substances. These properties are depended not only upon way of soil management, but also upon climatic effects, such are rainfall, temperature, elevation above sea-level, level of underground water and content of clay. Significantly influenced factors are content and form of organic carbon which is very tightly bonded to humic substances. In this work the humic acids content and properties progression was studied in given time period. Also the effect of crop rotations to changes of physical and chemical properties of humic acids in soil environment was observed. Diploma thesis was realized in co-operation with Mendel University in Brno, which supplied elaborating samples. Studied soil samples were taken from humus horizon Cambisol modal Vatín during years 1999–2006, always in autumn. Individual samples were characterized by available analytical methods, which are generally used in humic substances research area. They are especially fluorescence spectrometry, UV-VIS and infrared spectrometry and acid-base and conductometric titrations.
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Analysis of humic acids solutions after their decomposition by diaphragm discharge
Totová, Ivana ; Švejdová, Dana (referee) ; Kozáková, Zdenka (advisor)
Preliminary results of research focused on the applications of DC diaphragm discharge in water solutions containing humic substances are presented in this diploma thesis. Electrical discharges in water produce various reactive species such as radicals (•OH, •O, •H), ions and molecules (H2O2, O3). These species have high oxidation potential and thus they easily react with order species and molecules. Such reactions could lead, for example, to destruction of organic pollutants dissolved in water. This work studies this effect on humic matters that can be contained in water coming from floods. Diaphragm discharge investigated by this work was created in the reactor using konstant DC high voltage up to 2 kV that gave the total input power from 100 to 200 W. Breakdown and discharge ignition started in the pin-hole in the dielectric barrier separating two electrode spaces (anode and cathode space). Presented work investigates decomposition of humic substances by the electric discharge in the dependence of solution properties and discharge conditions. Parameters such as initial solution conductivity, electrolyte kind or input power have been investigated. Moreover, substantial effect of pH on humic acid decomposition has been observed. Refraktometry and absorption spectroscopy in UV-VIS region together with fluorescence spectroscopy has been used for the detection of changes in humic solutions.
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