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Conformation and molecular organization of humic acids in aqueous solutions
Věžníková, Kateřina ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
This diploma thesis deals with the conformation and molecular organization of humic acids in aqueous solutions. Humic substances have heterogeneous and polydisperse nature, therefore their secondary chemical structure has not yet been defined properly, neither has their conformational arrangement. The conformation of humic substances in the solutions is mainly stabilized by weak disperse forces, such as Van der Waals, -, CH- interactions and hydrogen bonds. Humic substances in the solutions tend to form aggregates that are held together mostly by the intermolecular hydrophobic interactions. Concentration series of humic acids were prepared in three different mediums of constant ionic strength: NaOH and NaCl (prepared either by neutralization NaOH by HCl or direct dilution by solution of NaCl). Several analytical methods have been used to determine conformation and molecular organization of humic acids: potentiometric determination of pH, direct conductometry, ultraviolet and visible spectroscopy, density measurement, dynamic light scattering, laser Doppler velocimetry and high resolution ultrasound spectrometry. It was confirmed that the conformation and molecular organization of humic acids in aqueous solutions depend not only on pH of medium, but they also depend on chemical nature and concentration with the same pH. Results showed that hydrodynamic diameter of particles is significantly increasing in NaCl medium prepared by neutralization NaOH by HCl, particularly at low concentrations, which corresponds to higher values of zeta potential obtained. Concentration dependencies of ultrasonic velocity and compressibility also indicate the changes in conformation and molecular organization corresponding with results from other methods used.
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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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Influence of compost application on properties of soil humic substances
Enev, Vojtěch ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The aim of this diploma thesis is to study to the influence of compost addition to soil humic substances extracted from blackland luvicsol. Humic substances extracted from soil and from compost were characterized by titration with potentiometrical and conductival indication, UV-VIS, FT-IR and 3D EEM fluorescential spectroscopy. Compost in amount of 124, 239 and 478 t/ha was applicated and manured into dept of 150 mm at blackland luvicsol. The main aim of thesis was the appraisal of compost influence into fluorescent attributes of soil HS and localization of fluorescent peaks at excitation emission spectrums. Next part of diploma thesis was focused on the study of spectroscopic attributes of soil HS and compost by UV-VIS and infrared spectroscopy with Fourier transformation. Humic substances were characterized by humifical index E4/E6 and transmissional vibratile spectrums. The last aim of diploma thesis were the characterization of soil HS extracts and compost by acidimetral titration. For each sample was calculated value of H+ ionts amount of substance from measured titrational curves.
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Fluorescence of soil and lignite humic substances
Konečná, Soňa ; Pospíšilová, Ľubica (referee) ; Fasurová, Naděžda (advisor)
The purpose the diploma thesis was to determine main fluorophores of soil and lignite humic substances using methods of 2D synchronous fluorescence spectroscopy (SFS) and 3D SFS. These fluorescence methods are frequently used for characterization multifluorophore systems. Measured synchronous spectra were compared with standards IHSS. Next to that the aim was to find differences between chosen samples of humic and fulvic acids.
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Following of cooper complexation with humic acids by fluorescence method
Hladík, Tomáš ; Pospíšilová, Ľubica (referee) ; Fasurová, Naděžda (advisor)
Humic acids have high ability to form stable complexes with copper ions, which influences their toxicity in environment. Fluorescent properties of sodium salt of humic acid, humate, isolated from South Moravian lignite, and its complexation behaviour with copper ions were investigated using emission, excitation and synchronous fluorescence spectroscopy. Both fluorescence emission and synchronous fluorescence spectra showed that humate form complex with copper since fluorescence intensity was quenched upon addition of copper ions to the humate samples. The aim of the diploma thesis was to found applicable ion concentration to observation fluorescence quenching and to determine the main fluorophore, which is affected by complexation through the use of synchronous fluorescence spectroscopy.
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Fluorescence spectroscopy of humic acids by excitation-emission matrix.
Mlčoch, Tomáš ; Pospíšilová, Ľubica (referee) ; Fasurová, Naděžda (advisor)
The aim of the diploma thesis was measurement and characterization of EEM (excitation emisssion spectra) of IHSS humic acids standards and soil, lignite humic and fulvic acids and humates prepared from different sources. The aim was to follow the differences in their fluorescence spectra and to determine precise location of fluorescence peaks. Target of this work was to find the optimal way for exporting of scan data to the 3D EEM spectrofluorographs. The dependence of relative intensity of fluorescence on pH value was studied further.
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Transport properties of humic gels
Sárová, Michaela ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
This bachelor’s thesis is focused on study of transport properties of humic gels. For research of these properties was used diffusion method of organic dyes in diffusion cells which is based on spectrophotometric monitoring of concentration changes depending on time. Dyes used in the experiment were specifically methylene blue and rhodamine 6G and diffusion experiments were performed on an agarose hydrogel without the addition of humic acid, with the addition of unmethylated humic acid and then with the addition of methylated humic acid. The aim of this thesis was to investigate the effects of interactions between diffusing dye and the particular type of gel to the resultant effective diffusion coefficient of dye. It has been found that the presence of humic acid in agarose hydrogel greatly influences the transport of dyes.
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Diffusion in humic gels.
Královič, Michal ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
This bachelor thesis is focuses on study of heavy metals diffusion in humic gels. The objective of the work was to verify, whether the diffusion is influenced by methylation of humic acid. Cupric and nickel cation was used in this thesis. Absorbance of solutions in acceptor and donor diffusion cell part was measured spektrofotometrically.
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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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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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