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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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New Methods of Cross-linking of Humic Substances
Lepíková, Jana ; Sedláček, Petr (referee) ; Kalina, Michal (advisor)
This bachelor thesis was focused on the study of crosslinking of humic substances. The main aim of this work was to find and optimize utilization of new crosslinking agents for humic acids. Commercial product – lignohumate – was also used in the work as comparative sample. Two groups of crosslinking agents were studied in this work – multivalent metals (CaCl2, MgCl2) and citric acid. In all cases the studied hydrogels were cross-linked by means of chemical valences. All prepared hydrogels were characterized using the determination of their inner pH, density and concent of dry matter. The process of aging of hydrogels – syneresis – was also studied. The main experimental method applied for hydrogels characterization was rheology. Prepared hydrogels represent interesting materials for following studies and also for possible future practical applications.
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Transport of phamaceuticals in reactive hydrogels
Kotradyová, Viktória ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
The bachelor thesis focuses on a problem associated with diffusion processes of antibiotics in agarose hydrogels enriched with humic acids. The soil model system simulates the transport of these pollutants and demonstrates the ability of the humic acids to bind and retain these substances, thereby preventing their subsequent contamination at unintentional places. The theoretical section encompasses an overview of the occurrence of pharmaceuticals in soil and water systems; it also provides information about their behaviour, effects, degradation, and potential outcomes in nature. It further clarifies basic knowledge of soil components, in particular humic acids. Furthermore, the mechanism behind the diffusion processes is explicated. Within the experimental part, the diffusion of the sulfomethoxazole and sulfapyridine in two types of agarose hydrogels was examined. Firstly, the pure agarose hydrogel was used and secondly, the addition of the active agent in the form of humic acids was performed. The method of diffusion from continuous source was utilized, followed by measuring through UV-VIS spectrometry for 21 days. The study aimed to compare the results and to establish the diffusion coefficients of the pharmaceuticals in both types of hydrogels.
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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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Reactivity of modified humic gels
Lang, David ; Sedláček, Petr (referee) ; Klučáková, Martina (advisor)
This bachelor thesis deals with humic acid gels and their ability to bind metallic ions on their surface. In the thesis the adsorption of copper ions on humic gels was studied. The gels were prepared by dissolving the humic acid in sodium hydroxide or sodium tripolyphosphate and then by precipitating with hydrochloric acid or magnesium chloride. Adsorption was studied at different concentrations of the copper (II) chloride and measured on UV-VIS spectrophotometer. It was proved from measuring that gels made from sodium tripolyphosphate are adsorbing less copper ions than the ones prepared by sodium hydroxide. Also, the copper ions are bound with smaller force on gels prepared with polyphosphate. Gels precipitated with magnesium chloride adsorb much more than gels precipitated with acid, Thus the extracted amounts are bigger.
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Humic substances - colloidal transport system of plant nutrients
Hudlíková, Iva ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The thesis deals with humic substances as major components of soil organic carbon during nutrients transport to plants root system. Literature research is focused on humic substances, adsorbing complex and transport of soil substances to plants. The experimental part of the work concentrates on interaction of humic acid with nitrates. A part of the work was humic acid characterization, and determination of titratable acidity and acidity COOH values.
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Hydration of biopolymers
Šméralová, Ester ; Smilková, Marcela (referee) ; Klučáková, Martina (advisor)
Presented bachelor's thesis focuses on the study of hydration of selected biopolymers – humic acids, chitosan, hyaluronic acid (low molecular weight and high molecular weight) and dextran. Thermogravimetric analysis TGA is used t determine the original moisture content of the samples. Two calorimetric methods were used for subsequent observations of changes in their chemical and mechanical properties in the presence of water – differential scanning calorimetry DSC and perfusion calorimetry.
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The Interaction of Graphene Oxide with Humic Acids, a Computational Study
FERLIN, Stefan
This study was focused on the interactions of Graphene oxide with humic acids in aqueous solutions. Additionally, to this work, Graphene oxide and water interactions with and without the addition of ions were studied. The behavior of a fulvic acid in the presence of Graphene oxide has been investigated as well. The study was performed using computer simulations that were achieved by Molecular Dynamics simulations. These simulations provided useful data on a nanometer scale.
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Transport of phamaceuticals in reactive hydrogels
Kotradyová, Viktória ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
The bachelor thesis focuses on a problem associated with diffusion processes of antibiotics in agarose hydrogels enriched with humic acids. The soil model system simulates the transport of these pollutants and demonstrates the ability of the humic acids to bind and retain these substances, thereby preventing their subsequent contamination at unintentional places. The theoretical section encompasses an overview of the occurrence of pharmaceuticals in soil and water systems; it also provides information about their behaviour, effects, degradation, and potential outcomes in nature. It further clarifies basic knowledge of soil components, in particular humic acids. Furthermore, the mechanism behind the diffusion processes is explicated. Within the experimental part, the diffusion of the sulfomethoxazole and sulfapyridine in two types of agarose hydrogels was examined. Firstly, the pure agarose hydrogel was used and secondly, the addition of the active agent in the form of humic acids was performed. The method of diffusion from continuous source was utilized, followed by measuring through UV-VIS spectrometry for 21 days. The study aimed to compare the results and to establish the diffusion coefficients of the pharmaceuticals in both types of hydrogels.
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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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