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Study of interaction between hyaluronan and phospholipid in a presence of biocompatible non-ionic surfactant
Burdíková, Jana ; Klučáková, Martina (referee) ; Mravec, Filip (advisor)
This work is based on investigation of aggregation behavior of sugar surfactants and sn-glycero-dipalmitoylphosphatidylcholin (DPPC) in aqueous environment and on study of the interactions in nonionic surfactant-DPPC and DPPC-nonionic surfactant-hyaluronan systems. Sugar surfactants were used from non-ionic surfactants. The behavior of each systems was studied by fluorescence spectroscopy. Values of critical micellar concentrations (CMC) of sugar surfactants, begining of aggregation of DPPC, DPPC aggregation effect of sugar surfactants and the effect of hyaluronan on the system non-ionic surfactant-DPPC has been investigated. Also CMC of the CPC (cetylpyrimidium chloride), which was used for fluorescence quenching in the determination of aggregate numbers of sugar surfactants, has been determined. Fluorescent probes pyrene, perylene, nile red, acridine orange and hydrophobic dye sudan red were used for measurements.
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Characterization of methylated humic acids
Solná, Irena ; Kislinger, Jiří (referee) ; Klučáková, Martina (advisor)
The main concern of this bachelor thesis was a characterization of the properties of methylated humic acids. Retrieval on modifications of acidic functional groups of humic substances was done. In addition appropriate experimental methods for assessing the impact of methylation of carboxylic groups of humic acids were selected. Methylation of formentioned carboxylic groups is used to improve stability of humic acids while working with them. The sample of methylated humic acids, produced by the University of Poitiers in France, was investigated by the following methods: UV-Vis spectroscopy, FT-IR spectroscopy, fluorescence spectroscopy and thermal analysis - TGA, DSC. The degree of methylation of carboxylic functional groups of methylated humic acids was considered using an indirect titration. Results were trade-off with the sample without methylation. The impact of gelation on properties of methylated and non-methylated humic acids was also studied.
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Bond strength of metal ions in humic gels
Potočková, Jana ; Sedláček, Petr (referee) ; Klučáková, Martina (advisor)
This thesis deals with the study of bond strength of Cu2+ ions in humic gels. Two methods of extraction were used during the study, sequential and fractional extractions. During the fractional extraction leaching of copper proceeds in single agents, whereas during the sequential extraction leaching proceeds gradually in all extraction agents. Destilled water, 1M MgCl2, 1M HCl and 0,025M NH4EDTA were applied like extraction reagents. Amounts of Cu2+ ions in leaches after extraction were measured by UV-VIS spectrometry. By using extractions was obtained the fractionation of Cu2+ ions according to bond strength in humic gel.
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Solubility and dissociation of humic acids
Kratochvílová, Romana ; Jaroslav,, Záhora (referee) ; Klučáková, Martina (advisor)
The behaviour of humic acids in aqueous solutions is closely connected to the content of acid functional groups and their dissociation abilities. The titration methods are the most often used for the research of acid-basic characteristics of humic acids, their results should lead to the determination of the content of functional groups and their pKa. However the determined values depend on many factors including the titration speed. The aim of this bachelor’s thesis is to verify the possibility of UV/VIS spectrophotometry´s use as alternative method for the determination of pKa of humic acids and to compare the gained results with so far used method according to Henderson-Hasselbach. The principle of newly used spectrophotometry method is the preparation of humic acids solutions in three different media with different pH values. Acid groups of humic acids are practically completely dissociated in intensely basic environment and the measured absorbance is caused by anion of „humate“. On the contrary their dissociation in acid environment is suppressed so much that we measure the absorbance of non-dissociated molecules of humic acids. It was found out that after the modification it was possible to use the spectrophotometry method for the determination of pKa of these substances, while the use of method was verified within the three different samples of humic acids. The optimal ratio humic acids – water and the extent of wavelength for measuring UV/VIS spectra were determined. It was proved that the values of pKa determinated by these methods better describe the real dissociation behaviour of humic acids in water than traditional Henderson-Hasselbach method. The UV/VIS spectra gained in combination with the results of pH measuring and the conductivity next showed the differences in the behaviour of differently prepared samples of humic acids.
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Rheology of humic gel
Smilek, Jiří ; Gregorová, Eva (referee) ; Klučáková, Martina (advisor)
The main aim of the bachelor thesis was to test several modifications of humic hydrogels’ preparation method and to discuss their effects on mainly viscoelastic properties of resulting materials. Main conditions, tested in the experimental part, were presence of acidic impurities from the gelation step in the gel and an addition of cations with a higher valence during or after the preparation step. The most important evaluated parameters of the materials were inner pH, solid content and mainly basic viscoelastic characteristics.
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Models for complexation of humic compounds
Věžníková, Kateřina ; Jaroslav,, Záhora (referee) ; Klučáková, Martina (advisor)
This bachelors thesis deals with interactions of copper ions with humic acids. The bond between metal ions and humic acids is formed mainly trough carboxylic and phenolic groups. Mechanism of these interactions is not so far enlighted. Essential part in this, is reality that humic acids are not chemical individuals, but polydisperse mixtures of substances. This work contains interactions of metal ions with model compounds like citric acid, salicylic acid, pthalic acid, hydroquinone, catechol and EDTA, which simulates possible binding sites in the structure of humic acids. Several analytical methods have been used to study this problems: potentiometry (pH), conductometry and UV/VIS spectroscopy. As a model metal ion has been chosen copper cation because of its high afinity to humic acids.
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Mathematical modelling diffusion of metal ions in humic gel
Masár, Lukáš ; Ing. Eva Gregorová,CSc. (referee) ; Klučáková, Martina (advisor)
The subject of this bachelor thesis was simulation of diffusion processes proceeding in the reactive gelous media using the COMSOL Multiphysics software. The aim of this study was to develop a comprehensive set of models available for the interpretation of experimental data obtained in the study of metal ions transport in the humic acids hydrogel. The main consideration was given to the influence of porosity modelling and chemical interactions on the diffusion characteristics (mainly diffusion flow). Within the simulation of the influence of chemical reactions, different kinetic models were used (one-way reaction of first and second order and reverse reaction).
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Preparation of mixed colloids of humic acids with biopolymers
Ondruch, Pavel ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
This bachelor’s thesis discusses an applicability of innovative colloidal forms of humic acids, prepared by a complexation with biopolymer chitosan. In experimental part, suitable procedures have been proposed and optimized for the preparation of hydrogels and xerogels made of these abundant polymeric substrates. In characterization of resulting materials, major attention was paid to the determination of the water content and the swelling ability. Besides, mechanical properties were studied as well. The development of a desired material aims at an industrial or agricultural utilization of sorption abilities and a tendency to immobilize various pollutants in the environment. Another advantage is represented by the ability to control the release of humic substances from the gel to environments.
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