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Fractionation of humic acids isolated from lignite
Moťka, Pavel ; Barančíková, Gabriela (referee) ; Klučáková, Martina (advisor)
The diploma thesis deals with lignitic humic acids. Bibliographic search can be divided into three parts. The aim of the first part is characterization of humic substances, presence, composition, structure and exploitation especially of humic acids. The second part describes a division of heterogeneous mixture of humic acids into closed fractions with more specific properties. The final part is a study of solubility of humic acids. The experimental part of the diploma thesis is structured similarly. In this work, a gradual fractionation with pH is used. Obtained fractions were characterized by UV/VIS and FT-IR spectroscopy. We assessed the portion of ash and carboxyl groups have been identified. Subsequently, all fractions extracted by gradual fractionation as well as some soluble fractions obtained by direct fractionation have been analyzed in view of solubility and their behaviour in water environment. Both used methods were compared.
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Stability of soil organic matter and humic substances
Nováková, Šárka ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
This diploma thesis is focused on changes of stability in organic matter by extraction in different agents. Two soils of a different type and isolated humic acids were used for stability determination. Extraction agents were selected usually used for soil metal extraction, and a changes in the structure of the organic matter was observed. Samples were characterized using FTIR analysis and elemental analysis, the extracts were measured by UV-VIS spectroscopy, absorption ratios E2/E3, E4/E6 were discovered, dynamic light scattering were determined for particle size distributions. Next part of the thesis was the assessment of the change of thermal stability using thermogravimetric analysis and differential scanning calorimetry, degradation temperatures of the extracted samples were discovered and compared with the original samples.
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Influence of humic acids on the corrosion behavior of low carbon steel
Horák, Tomáš ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
This diploma thesis deals with influence of humic acid from lignite on corrosion behavior of low carbon steel S235JR in the environment of 0,1 M NaCl at three diffrent pH values (5, 7 and 9). Humic acid was fractionated into three soluable fractions at pH 5, 7 and 9. Corrosion behavior was studied by potentiodynamic polarization, electrochemical impedance spectroscopy and immersion tests. Surface analysis of low carbon steel was carried out before and after corrosion tests as well as analysis of corrosion medium. The results show that humic acid has negative effect on corrosion of low carbon steel in comparison with 0,1 M NaCl solution, because in presence of humic acid, the corrosion rate is higher. The negative effect was attributed to the formation of complexes of humic acid with released iron ions. The main corrosion product on the surface of low carbon steel after exposure to the 0,1 M NaCl was magnetite. Presence of humic acid in 0,1 M NaCl caused formation of lepidocrocite as main corrosion product. Potencial mechanism that is trying to clarify the formation of corrosion products and influence of humic acid on corrosion behavior is discussed in this thesis.
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Interactions of pharmaceuticals with humic acids
Libiger, Jan ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
The bachelor thesis is focused on interaction of drugs with humic substances, which are part of organic soil matter. The results would help in understanding the behavior of drugs in soil and other natural systems. Three drugs were selected. Humic acid was selected as a sorbent, which was extracted from lignin, the lower one is assumed to be the same as that in organic soil. Based on a comparison of the measurement results using the UV-VIS method, it was determined how much the acid of the given drug is able to absorb and how much it is released back into the water. The theoretical part deals with the information about soil organic matter, with the information about humic substances, with the information about drugs such as ibuprofen, sulfamethoxazol or sulfapyridine. Furthermore, the theoretical part deals with methods of analysis.
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Determination of acidic groups in humic substances.
Kabeláčová, Kateřina ; Sedláček, Petr (referee) ; Janeček, Jiří (advisor)
Within this bachelor thesis we compared three method to determine the acidity of humic substances. We employed the baryta-method (which determines the total acidity), the Ca-acetate method (determines the content of carboxylic groups only) and the technique of Ray von Wandruszka. This method should provide the content of groups dissociable at pH>12. We used four different samples of humic acids isolated from two sources (lignite and peat). While the differences between results of baryta and Ca-acetate methods were expected and can be easily explained, the values of acidity obtained by the von Wandruszka method represent roughly one half of the results of Ca-acetate method and almost only ten percent of the baryta results. In the cases of baryta as well as von Wandruszka methods we observed a dependency of the results on the time-length of the analysis. In the theoretical part the characterisation, divided, creation, structure and properties of humic substances are summarized. In the end of theoretical part are described using method for analysis of humic acids.
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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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Effect of humic acid on the corrosion of carbon steel
Horák, Tomáš ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
Bachelor thesis deals with influence of humic acids on corrosion of ČSN 12020 steel. For this purpose, potentiodynamic tests and electrochemical impedance spectroscopy (EIS) in leaches of humic acids, isolated from South Moravian lignite were executed. Results suggest that corrosion is initially promoted by humic acids, but after a longer time (about 98 hours) an inhibitory effect is exerted due to the adsorption of humic acids on the corrosion products. Adsorption efficiency of humic acids on surface of corrosion products was about 30 %. Results also suggest that the presence of humic acids may influence the composition of corrosion products of the steel.
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Influence of humic acids on the corrosion behavior of low carbon steel
Horák, Tomáš ; Buchtík, Martin (referee) ; Doskočil, Leoš (advisor)
This diploma thesis deals with influence of humic acid from lignite on corrosion behavior of low carbon steel S235JR in the environment of 0,1 M NaCl at three diffrent pH values (5, 7 and 9). Humic acid was fractionated into three soluable fractions at pH 5, 7 and 9. Corrosion behavior was studied by potentiodynamic polarization, electrochemical impedance spectroscopy and immersion tests. Surface analysis of low carbon steel was carried out before and after corrosion tests as well as analysis of corrosion medium. The results show that humic acid has negative effect on corrosion of low carbon steel in comparison with 0,1 M NaCl solution, because in presence of humic acid, the corrosion rate is higher. The negative effect was attributed to the formation of complexes of humic acid with released iron ions. The main corrosion product on the surface of low carbon steel after exposure to the 0,1 M NaCl was magnetite. Presence of humic acid in 0,1 M NaCl caused formation of lepidocrocite as main corrosion product. Potencial mechanism that is trying to clarify the formation of corrosion products and influence of humic acid on corrosion behavior is discussed in this thesis.
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Interactions of pharmaceuticals with humic acids
Libiger, Jan ; Enev, Vojtěch (referee) ; Klučáková, Martina (advisor)
The bachelor thesis is focused on interaction of drugs with humic substances, which are part of organic soil matter. The results would help in understanding the behavior of drugs in soil and other natural systems. Three drugs were selected. Humic acid was selected as a sorbent, which was extracted from lignin, the lower one is assumed to be the same as that in organic soil. Based on a comparison of the measurement results using the UV-VIS method, it was determined how much the acid of the given drug is able to absorb and how much it is released back into the water. The theoretical part deals with the information about soil organic matter, with the information about humic substances, with the information about drugs such as ibuprofen, sulfamethoxazol or sulfapyridine. Furthermore, the theoretical part deals with methods of analysis.
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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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