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Transport Properties of PVA Hydrogels
Nádvorník, Filip ; Trudičová, Monika (referee) ; Kalina, Michal (advisor)
This bachelor thesis focuses on the study of transport properties of PVA hydrogels. The preparation of PVA hydrogels was optimized using rheological tests and visual observation. The freeze – thawing method was used for the PVA gelation process. Probes carrying a charge on functional groups in aqueous media, namely methylene blue, eosin and riboflavin, were incorporated into PVA hydrogels during the preparation. The mechanical properties of these hydrogels were compared with those of pure PVA hydrogels. Diffusion tests were then carried out where the given dye was monitored from the hydrogel into the surrounding environment using UV-VIS spectroscopy. The obtained results showed that the hydrogel containing the probe with a positive partial charge (methylene blue) showed the greatest willingness to release the dye, while the hydrogel containing the probe without the charge (riboflavin) was released into the environment minimally.
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Involvement of vibrational spectroscopy in the study on interactions of natural organic matter with model environmental pollutants.
Stehlíková, Kristína ; Enev, Vojtěch (referee) ; Sedláček, Petr (advisor)
The main objective of this diploma thesis was to verify the potential of using advanced infrared spectra processing techniques – specifically the principal component analysis (PCA) – in order to monitor the interaction of natural organic matter with organic pollutants. Natural organic matter was represented by standard IHSS Leonardite humic acid, while the aromatic dyes methylene blue and Rhodamine 6G and the aliphatic substance Septonex were chosen as representatives of organic ions. Their interactions were monitored using Fourier-transform infrared spectroscopy, the use of which for this purpose was verified in my bachelor's thesis. Principal component analysis was finally applied to the obtained infrared spectra of the formed complexes and prepared blank samples, which helped to reveal spectral changes at first glance unrecognizable in the spectra themselves. It was found out that the most likely mechanism of humic acid interaction with aromatic pollutants is a - interaction, while the electrostatic nature of the interaction is assumed for the binding of aliphatic substances.
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Transport Properties of Thin Films Based on Polyvinylalcohol
Blažková, Dominika ; Smilek, Jiří (referee) ; Kalina, Michal (advisor)
This bachelor thesis deals with the optimization of the preparation of hydrogel thin films based on polyvinyl alcohol (PVA). The first step was to optimize the preparation of films. PVA, with a molecular weight of 130 kDa, was used for the preparation of films and 10 wt.% solutions in ultrapure water were prepared from it. The heating duration time of the solution was set at 1.5 h at 90 °C. This was followed by drying at 50 °C for 24 h. Subsequently, PVA films were also prepared from solutions of methylene blue in water and from solutions of methylene blue in an aqueous NaCl solution. The prepared films were subsequently characterized by measuring their thickness, swelling ability, specific surface area and diffusion properties. The morphology of the PVA films was also visualized by SEM microscopy. All prepared films were smooth and had a very small specific surface area. The transport properties were monitored by the method of release into solution and Methylene blue was used as a probe. Release into 5, 10 and 20 ml of ultrapure water was observed. The results obtained show that the most methylene blue was released into the solution with the greatest volume and the release of methylene blue from the PVA film takes place freely without significant interaction with the matrix of the PVA film.
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Hydrogels with carbon fibers
Kučerová, Barbora ; Bouška,, Marek (referee) ; Pekař, Miloslav (advisor)
This diploma thesis is focused on the study of the behaviour of carbon fibers in the hydrogel, especially the viscoelastic modules od these gels ort he coefficient of color transmission through the gel. The main goals were to optimize the samples and measure their viscoelastic modules on a rheometer, in several different modes. This was followed by simulation of physiological conditions for selected samples and their measurement on the rheometer. There was also an experiment of continuous diffusion in cuvettes, in which the penetration of the dye through the gel with the addition of fibers and for comparison also without them. Last but not least diffusion pairs were prepared.
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Photocatalytic sensor of oxygen
Filipi, Denisa ; Kubáč,, Lubomír (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with the optimization of inks for the preparation of photocatalytic oxygen indicator.The aim was to prepare a photocatalytic oxygen indicator with sufficient colour change after photoreduction and after reverse photooxidation.The indicator is based on semiconductor particles (TiO2), a sacrificial electron donor, a redox dye and a polymer which serves as a binder. The effect of the polymer used on the appearance of the prepared layers deposited on the PET film was investigated. The effect of the concentration of sacrificial electron donor on the rate of photoreduction (transition to the colourless leuco form) and reverse photooxidation of the indicator (transition of the leuco form to the coloured form) was also studied. Based on the study of the indicators, the rate constants for photoreduction and photooxidation of the prepared indicators were determined.
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Influence of the surface hydrophobicity and charge of the molecule for drop coating deposition Raman spectroscopy
Bura, Radek ; Kočišová, Eva (advisor) ; Procházka, Marek (referee)
Raman spectroscopy is an optical vibrational spectroscopic technique suited for a study of biomolecules and their interactions. In contrast to classical Raman spectroscopy, Drop-Coating Deposition Raman spectroscopy (DCDR) enables due to a preconcentration of the sample dried on a special hydrophobic surface to acquire a high-quality spectrum even in case of low concentrated samples. In collaboration with Department of Macromolecular Physics of the Faculty of Mathematics and Physics at Charles University, the three special surfaces - substrates - with different wettability (hydrophobicity) and roughness on the basis of silvers nanoparticles have been prepared. Solutions of methylene blue and glutamic acid at different concentrations and pH were dropped on these substrates. Nanoparticles size was determined. It was shown, that with increasing number of sputtered nanoparticles, the roughness of the substrates increased also. More roughened substrates show a higher static contact angle. The dynamics of droplet drying and the preconcentration of substances in the dried deposit were monitored. The preconcentration was assessed from the first subspectrum obtained from a factor analysis performed on series of measured Raman spectra from dried deposits. There was none among the substrates on which there would...
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Outdoor applications of photocatalytic materials
Šimončičová, Monika ; Králová, Marcela (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with the evaluation and optimization of the method for the determination of photocatalytic activity of facade coating layers with and without photocatalyst admixture titanium dioxide. The layers are tested by the photooxidation of the organic dyes Acid orange 7 and methylene blue, which are model compounds of pollution. Degradation of organic dyes is monitored by UV-VIS spectrophotometry and evaluated by determination of rate constants and specific photoactivity. The aim is to find out which of the facade coating has the highest photoactivity.
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Transport processes in hydrogels
Sárová, Michaela ; Kalina, Michal (referee) ; Klučáková, Martina (advisor)
This master's thesis is focused on study of transport processes in hydrogels based on humic acids. For this purpose is used methods unsteady diffusion in cuvettes, which was studied the transport of organic dyes, specifically methylene blue and rhodamine 6G, in agarose hydrogel without the addition and with the addition of individual standards humic acids (Leonardite, Elliott Soil, Suwannee River II and Pahokee Peat). This method is based on spectrophotometric monitoring of concentration changes of dyes depending on space of the cuvette and on time. 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. The experiments indicate that the presence of humic acid in the hydrogel greatly affects the transport of selected dyes.
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