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Development of new grouting materials for reverse grouting of sewers
Dolák, Martin ; Dohnálek,, Pavel (referee) ; Drochytka, Rostislav (advisor)
ABSTRACT This thesis deals with the development of silicate based reverse grouts for the purpose of rehabilitation of sewers. The work also examines the possibility of substitution of basic input raw materials with secondary raw materials, meaning replacements of both filler components and binder components. As secondary raw materials, we refer to wastes from the production process which, after the necessary treatment, are used in another production. The development and experimental verification of the functionality of the developed grout was focused mainly on the use of secondary raw materials as much as possible, while maintaining or even improving its physical and mechanical properties. Based on the results of the work, it can be stated that with a 100% replacement rate of filler components in combination with 20% replacement rate of binder components, it is possible to largely maintain the properties of the material, or even optimize them. The results of the thesis also point to the possibility of reducing the economic and environmental demands of production of building materials.
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Dissolution of silicates for carbon dioxide mineral storage
Křečková, Magdaléna ; Havlica, Jaromír (referee) ; Ptáček, Petr (advisor)
The degradability of wollastonite, montmorillonite and talc in an aqueous solution of acetic acid at different temperatures is main object of this study. Mineral carbonation, i.e. the reaction of calcium and magnesium presented in these three silicates, is a novel and promising approach to carbon dioxide capture and long-term storage. The kinetic of wollastonite, montmorillonite and talc dissolution is studied due to assessment of their efficiency for CCS technologies. The dissolution kinetic is discovered with using measured time dependence of Ca2+ and Mg2+ leached ions concentration.
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Sol-gel synthesis of ternary ZnxTiyOz nanostructures for applications in solar cell technologies and photonics
Mrázek, Jan ; Nižňanský, Daniel (advisor) ; Pinkas, Jiří (referee) ; Pollert, Emil (referee)
The presented study deals with the sol-gel synthesis of nanocrystalline ternary phases of the general formula ZnxTiyOz, their characterization and potential application in photonics. Achieved results brings new fundamental knowledge about the processes leading to the formation of ZnxTiyOz nanocrystals from amorphous xerogels and gives novel information about structural and opto-electrical properties of prepared materials. Based on the presented results, most of all up-to-date reported ZnxTiyOz compounds with tailored nanocrystalline size and structure can be prepared as powders or thin films. Two sol-gel approaches based on the cluster process and direct heteronucleation were employed to prepare initial sol. Sols were optionally doped by Eu3+ ions to evaluate the effects of rare earth element to crystallization properties of formed compounds. In the first part of our study crystallization properties and structural evolution of thermally treated xerogels were analyzed. As a result a versatile method allowing the preparation of inverse spinel Zn2TiO4, cubic defect spinel ZnTiO3 and rhombohedral ZnTiO3 with tailored nanocrystal sizes was established. Initial composition and thermal annealing allow us to prepare selected ternary phase with tailored nanocrystal size ranging from tens of nanometers up to...
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Bacterial role in silicate mineral alteration in near-neutral pH conditions
Duchoslav, Vojtěch ; Falteisek, Lukáš (advisor) ; Seydlová, Gabriela (referee)
It is well established that bacteria are able to catalyze dissolution of silicate minerals. Bacteria may dissolve silicates for two different purposes. They may use certain elements that can undergo redox transitions as substrates for their energetic metabolism or they can leach nutrients, that are otherwise unaccessible in their habitat. The main mechanisms of bacterially mediated silicate leaching are acidic or basic catalysis and surface complexation. The main nutrients extracted are K, Mg, P and Fe. The only element significantly exploited as substrate for dissimilative energetic metabolism is iron. In order to leach iron as a nutrient, even extremely strong complexants (i.e. siderophores) may be employed. However, only moderate complexing agents can serve to obtain iron as terminal electron acceptor. The second possibility is to reduce iron directly in the crystal grid by means of the conductive nanofibres. The oxidative dissolution of silicates by chemoautotrophs is rare, in contrast to that of sulfides. Bacterial dissolution of silicates leaves morphological and geochemical signatures, but it is still problematic to recognize and interpret them. Although it is well-known that bacteria can dissolve most of the rock-forming minerals in diverse environments we are unable to quantify their contribution...
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Development of new grouting materials for reverse grouting of sewers
Dolák, Martin ; Dohnálek,, Pavel (referee) ; Drochytka, Rostislav (advisor)
ABSTRACT This thesis deals with the development of silicate based reverse grouts for the purpose of rehabilitation of sewers. The work also examines the possibility of substitution of basic input raw materials with secondary raw materials, meaning replacements of both filler components and binder components. As secondary raw materials, we refer to wastes from the production process which, after the necessary treatment, are used in another production. The development and experimental verification of the functionality of the developed grout was focused mainly on the use of secondary raw materials as much as possible, while maintaining or even improving its physical and mechanical properties. Based on the results of the work, it can be stated that with a 100% replacement rate of filler components in combination with 20% replacement rate of binder components, it is possible to largely maintain the properties of the material, or even optimize them. The results of the thesis also point to the possibility of reducing the economic and environmental demands of production of building materials.
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In situ weathering experiments of sulphides and silicates
Jarošíková, Alice ; Mihaljevič, Martin (advisor) ; Drahota, Petr (referee)
Weathering is a natural process which is occuring on the Earth's surface. Its effect on minerals and other materials is significant. Besides mechanical alteration, the result of weathering can reach the chemical reactions, which can lead to contamination of the environment (e.g. ground water and soils). Not only for this reason has weathering become an object of intensive studies. In situ weathering experiments are one way of research. The aim of this bachelor thesis is to review the advantages and disadvantages of these experiments, to describe their course and the complications which can happen during the experiments, and how to use knowledge of these observations. Attention is also focused on several concrete experiments which were concerned with the weathering of sulphides and silicates, and where it is possible to observe these things on them.
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Bacterial role in silicate mineral alteration in near-neutral pH conditions
Duchoslav, Vojtěch ; Falteisek, Lukáš (advisor) ; Seydlová, Gabriela (referee)
It is well established that bacteria are able to catalyze dissolution of silicate minerals. Bacteria may dissolve silicates for two different purposes. They may use certain elements that can undergo redox transitions as substrates for their energetic metabolism or they can leach nutrients, that are otherwise unaccessible in their habitat. The main mechanisms of bacterially mediated silicate leaching are acidic or basic catalysis and surface complexation. The main nutrients extracted are K, Mg, P and Fe. The only element significantly exploited as substrate for dissimilative energetic metabolism is iron. In order to leach iron as a nutrient, even extremely strong complexants (i.e. siderophores) may be employed. However, only moderate complexing agents can serve to obtain iron as terminal electron acceptor. The second possibility is to reduce iron directly in the crystal grid by means of the conductive nanofibres. The oxidative dissolution of silicates by chemoautotrophs is rare, in contrast to that of sulfides. Bacterial dissolution of silicates leaves morphological and geochemical signatures, but it is still problematic to recognize and interpret them. Although it is well-known that bacteria can dissolve most of the rock-forming minerals in diverse environments we are unable to quantify their contribution...
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Sol-gel synthesis of ternary ZnxTiyOz nanostructures for applications in solar cell technologies and photonics
Mrázek, Jan ; Nižňanský, Daniel (advisor) ; Pinkas, Jiří (referee) ; Pollert, Emil (referee)
The presented study deals with the sol-gel synthesis of nanocrystalline ternary phases of the general formula ZnxTiyOz, their characterization and potential application in photonics. Achieved results brings new fundamental knowledge about the processes leading to the formation of ZnxTiyOz nanocrystals from amorphous xerogels and gives novel information about structural and opto-electrical properties of prepared materials. Based on the presented results, most of all up-to-date reported ZnxTiyOz compounds with tailored nanocrystalline size and structure can be prepared as powders or thin films. Two sol-gel approaches based on the cluster process and direct heteronucleation were employed to prepare initial sol. Sols were optionally doped by Eu3+ ions to evaluate the effects of rare earth element to crystallization properties of formed compounds. In the first part of our study crystallization properties and structural evolution of thermally treated xerogels were analyzed. As a result a versatile method allowing the preparation of inverse spinel Zn2TiO4, cubic defect spinel ZnTiO3 and rhombohedral ZnTiO3 with tailored nanocrystal sizes was established. Initial composition and thermal annealing allow us to prepare selected ternary phase with tailored nanocrystal size ranging from tens of nanometers up to...
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Dissolution of silicates for carbon dioxide mineral storage
Křečková, Magdaléna ; Havlica, Jaromír (referee) ; Ptáček, Petr (advisor)
The degradability of wollastonite, montmorillonite and talc in an aqueous solution of acetic acid at different temperatures is main object of this study. Mineral carbonation, i.e. the reaction of calcium and magnesium presented in these three silicates, is a novel and promising approach to carbon dioxide capture and long-term storage. The kinetic of wollastonite, montmorillonite and talc dissolution is studied due to assessment of their efficiency for CCS technologies. The dissolution kinetic is discovered with using measured time dependence of Ca2+ and Mg2+ leached ions concentration.
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