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Sequential fractionation of organic matter of humic acid isolated from Leonardite
Krist, Tomáš ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
The aim of the diploma thesis was to optimize the sequential fractionation method of organic matter to be used for physico-chemical characterization of extracted fractions. Humic acid isolated from oxidized brown coal of Leonardite was used as a source matrix of organic matter. An eluotropic series was assembled and sequential fractionation was performed by extraction on a Soxhlet apparatus. The original humic acid and fractions were characterized by elemental analysis (EA) and thermogravimetric analysis (TGA), followed by Fourier transform infrared spectrometry (FTIR), molecular absorption spectrometry (UV/VIS), fluorescence spectrometry and potentiometric titration. Atomic ratios were determined from the results of the elemental analysis. From the measured UV/Vis and fluorescence excitation and emission spectra, the absorption coefficients, resp. fluorescence coefficients. Used fractionation method proved to be a suitable method for studying HA structure. A total of 62 wt. % of initial materiál was extracted, indiivdual fraction amounted from 0.36–30.92 wt. %. From the results of the structural analysis, it is clear that with increasing polarity of the organic solvent, fractions with long aliphatic chains were first isolated and their aromaticity graddualy increased. Non-polar organic solvents were suitable for the extraction of lipid-like coumpounds, while the most polar organic fractions were rich in polar groups and their structual parameters were close to the original humic acid. The fraction extracted with acetonitrile was the most unique fraction. This fraction was rich on nitrogen and amine groups and was similar to protein-like structures. In the last two fractions, extracted with alcohols, a significant bathochromic shift typical of fluorophore type V was observed. Among other things, they were also characterized by a higher content of plant carbohydrate residues.
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Flame retarded polyolefins
Pařízek, Jan ; Poláček, Petr (referee) ; Kučera, František (advisor)
The theoretical part of the bachelor thesis deals with topics related to polyolefins and flammability of polymeric materials. The mechanisms of action of the most common flame retardants and methods of flame characterization are described. In the experimental part, polypropylene samples with flame retardants were prepared. The substances used were based on ammonium polyphosphate, melamine polyphosphate, aluminium hydroxide and expandable graphite. The samples were tested for flammability according to UL 94. Subsequently, the solubility of the polymer/flame retardant mixtures in water was investigated by Soxhlet extraction.
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Sequential fractionation of organic matter of humic acid isolated from Leonardite
Krist, Tomáš ; Doskočil, Leoš (referee) ; Enev, Vojtěch (advisor)
The aim of the diploma thesis was to optimize the sequential fractionation method of organic matter to be used for physico-chemical characterization of extracted fractions. Humic acid isolated from oxidized brown coal of Leonardite was used as a source matrix of organic matter. An eluotropic series was assembled and sequential fractionation was performed by extraction on a Soxhlet apparatus. The original humic acid and fractions were characterized by elemental analysis (EA) and thermogravimetric analysis (TGA), followed by Fourier transform infrared spectrometry (FTIR), molecular absorption spectrometry (UV/VIS), fluorescence spectrometry and potentiometric titration. Atomic ratios were determined from the results of the elemental analysis. From the measured UV/Vis and fluorescence excitation and emission spectra, the absorption coefficients, resp. fluorescence coefficients. Used fractionation method proved to be a suitable method for studying HA structure. A total of 62 wt. % of initial materiál was extracted, indiivdual fraction amounted from 0.36–30.92 wt. %. From the results of the structural analysis, it is clear that with increasing polarity of the organic solvent, fractions with long aliphatic chains were first isolated and their aromaticity graddualy increased. Non-polar organic solvents were suitable for the extraction of lipid-like coumpounds, while the most polar organic fractions were rich in polar groups and their structual parameters were close to the original humic acid. The fraction extracted with acetonitrile was the most unique fraction. This fraction was rich on nitrogen and amine groups and was similar to protein-like structures. In the last two fractions, extracted with alcohols, a significant bathochromic shift typical of fluorophore type V was observed. Among other things, they were also characterized by a higher content of plant carbohydrate residues.
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Zastoupení mastných kyselin ve vybraných cereálních potravinách
Kučerová, Kateřina
The diploma thesis consists of theoretical and practical part. In the theoretical part it deals with lipids and their role in human nutrition. I also characterized fatty acids and evaluated their health effects. Subsequently, I studied the theoretical basis of chromatographic methods focusing on gas chromatography, its instrumentation and evaluation. In the practical part I analysed the selected assortment of müsli bars by several producers. I focused on the quality of some müsli bars available on the Czech market, focusing mainly on fat content and fatty acid composition. As far as preparation of samples are concerned, it was necessary to lyophilize them first and then Soxhlet extraction followed. The actual determination of fatty acids was carried out using the method of gas chromatography and the results were statistically evaluated.
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