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Interactions of polycations and anionic surfactants
Szabová, Jana ; Krouská, Jitka (referee) ; Mravec, Filip (advisor)
This thesis deals with the study of interaction polycations and anionic sufactants with regard to phase separation in water and in physiological saline solution (0.15 moldm3 NaCl). First, the solubilizing experiments were made (using hydrophobic dye red oil O) for mapping behavior system SDS-DEAE. Then the aggregation behavior of surfactant was measured. Using solubilizing experiments the area for influence of addition dextran hydrochloride for aggregation was selected. This behavior was investigated by fluorescence spectroscopy using pyrene as fluorescence probe. The Critical Micellar and Agregation Concentration of studied system was determined and defined the area of phase separation. The influence of the process of preparing hydrogels by dry or wet path was studeid. The measurements revealed that the addition of salt and polymer has a considerable influence on value of CAC. It was also found, that increasing ionic strength affects the formation of a hydrogel. Finally, it was found that the process of preparing hydrogels does not affect formation of hydrogel.
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Hydrogels based on cationic polyelectrolytes
Jarábková, Sabína ; Lehocký,, Marián (referee) ; Pekař, Miloslav (advisor)
This diploma thesis deals with the study of physical hydrogels based on positively-charged polyelectrolyte. The study is to investigate the interaction of selected positively-charged polyelectrolytes with oppositely charged surfactants in water and in physiologicla saline solution (0.15 M NaCl). The influence of the process for preparing hydrogels. Hydrogels were prepared by dry or wet. Were tested solubilization abilities hydrogels prepared using the hydrophobic dye oil red O were also measured rheological properties of the hydrogels prepared using frequency oscillatory tests and flow tests, depending on the concentration of the polymer or surfactant. For the rheological experiments suggest that chitosan is capable of forming rigid hydrogels with better mechanical properties than the dextran in the presence of both surfactants. Selected samples were also carried out experiments using fluorescent sold prodan, nile red and -naphthol as fluorescent probes. And in selected experiments was determined by solids content in percentage depending on the concentration used polyelectrolytes or surfactants.
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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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Analysis of humic acids solutions after their decomposition by diaphragm discharge
Totová, Ivana ; Švejdová, Dana (referee) ; Kozáková, Zdenka (advisor)
Preliminary results of research focused on the applications of DC diaphragm discharge in water solutions containing humic substances are presented in this diploma thesis. Electrical discharges in water produce various reactive species such as radicals (•OH, •O, •H), ions and molecules (H2O2, O3). These species have high oxidation potential and thus they easily react with order species and molecules. Such reactions could lead, for example, to destruction of organic pollutants dissolved in water. This work studies this effect on humic matters that can be contained in water coming from floods. Diaphragm discharge investigated by this work was created in the reactor using konstant DC high voltage up to 2 kV that gave the total input power from 100 to 200 W. Breakdown and discharge ignition started in the pin-hole in the dielectric barrier separating two electrode spaces (anode and cathode space). Presented work investigates decomposition of humic substances by the electric discharge in the dependence of solution properties and discharge conditions. Parameters such as initial solution conductivity, electrolyte kind or input power have been investigated. Moreover, substantial effect of pH on humic acid decomposition has been observed. Refraktometry and absorption spectroscopy in UV-VIS region together with fluorescence spectroscopy has been used for the detection of changes in humic solutions.
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