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Photocatalytic activity of ZnxCd.sub.1-x./sub.S quantum dots in dependence on their composition
Praus, P. ; Svoboda, L. ; Hospodková, Alice ; Mamulová-Kutláková, K.
ZnxCd1-xS quantum dots (QDs) with the different composition x were prepared by precipitation of Zn and Cd acetates with sodium sulphide from aqueous colloid dispersions. Transition energies of these QDs were determined from UV-VIS spectra of the QDs colloid dispersions and consequently used for calculation of the QDs sizes according to the Schrödinger equation. The ZnCdS QDs size was found to be significantly influenced by their composition, decreased with increasing the Zn content. The QDs were also characterized by TEM, X-ray powder diffraction and PL. The photocatalytic activity of the QDs was studied using the methylene blue decomposition under UV irradiation with the maximum intensity of 365 nm. Different photocatalytic activity depending on the composition x was observed. Quantum levels of the QDs have important influence on their photocatalytic activity as a result of quantum size effect. The maximal photocatalytic activity was achieved for x=0.6.
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Deposition of the thin films for applications of advanced oxidation processes using metal dopants
KRAJČOVIČ, Jan
The aim of this diploma thesis is deposition of TiO2 thin films onto different types and sizes of substrates, and some of these layers dope by iron or silver. During the work was range of TiO2 layers created using a method of physical vapor deposition namely magnetron sputtering. For these processes was chosen the Dreva ARC 400 Hard Material Coating Plant device. The main aim of these depositions was to attempt to create TiO2 thin films on a substrates of larger surface than its in average laboratory processes usual. For this purpose were TiO2 layers deposited onto square glass plates of side length 10 cm. For comparsion and analysis were also as a substrates used microscope slides and fragments of silicon wafers. These substrates were used for testing of photocatalytic activity and on surface morphology (SEM). The theoretical part of this thesis aims to a methods of deposition TiO2 layers and their characteristics. In the experimental part is the used coating equipment and parameters of each deposition process described. Further the characteristics and results of individual experiments are described.
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Aplication of Photocatalytic Processes for Contaminated Water Cleaning
Maléterová, Ywetta ; Krejčíková, Simona ; Spáčilová, Lucie ; Cajthaml, Tomáš ; Kaštánek, František ; Šolcová, Olga
The necessity of finding the alternative solutions for environmental protection leads to development and use of the new technologies. Photo-catalysis has been applied as a promising technique for the wastewater decontamination and/or purification using semiconductor particles have found increasing interest to solve the resistant pollutants remove problems. This study is focused on verification of the specially designed photoactive materials and their modified versions suitable for photo-processes carried out upon illumination in the UV light.TiO2 as a photocatalyst immobilized in thin layers on glass beads or glass tubes were used for the degradation of 4-chlorophenol and endocrine disruptors namely 4-nonylphenol, 17-ethynylestradiol and bisphenol A in water solution with allowance of the toxicity of final water. Experiments demonstrate the efficiency of photocatalytic degradation for all compounds in both types of photocatalytic reactor (batch and continual arrangement) was 85% in average. The toxicity and the estrogenity of final water were monitored. The long term efficiency of titania catalyst was also proved.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22013103010060 - PDF
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Photocatalytic Degradation of Bisphenol A
Spáčilová, Lucie ; Maléterová, Ywetta ; Cajthaml, Tomáš ; Šolcová, Olga
Bisphenol A belongs to the group of the environmental estrogens that act as the hormonal system of the body. It is one of the most representative endocrine disruptors in wastewater. Bisphenol A gets into rivers from the production of polycarbonate, respectively, from the processing thereof. More than 75% of the Czech polycarbonate consumption is concentrated in three key economic sectors: automotive, construction, electronics and electrical industry.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22013102415320 - PDF
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Functional thin films for applications using advanced oxidation processes
ŠRAM, Vlastimil
This diploma thesis aims to optimalization the process of magnetron sputtering and creating of thin layers for use in advanced oxidation processes. During the work was created range of TiOx layers. For this process was used physical method of sputtering called PVD. The photocatalytic activity of the deposited films was tested by degradation of organic dyes Acid Orange 7. Furthermore, the layer was analyzed on surface morphology (SEM) and the layer thickness (profilometry). Study of created layers was focused on the link between the characteristics of each layer, deposition parameters and photocatalysis properties. Based on these results, the layers were applied in a system using AOP for the decomposition of organic substances. The first chapter is devoted to a summary of existing knowledge of photocatalysis and its principles. Another chapter is devoted to the theory and methods of applying thin layers and summary of knowledge of the low-pressure discharges. In the exprimental section there are described various components of the apparatus. Furthermore, the experimental part of the work focuses on the analysis of the optimization process of applying thin layers on titanium oxide. The last chapter of the thesis contains the results of the experiments on the basis of is designed another research progress of this issue.
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Sol-Gel Derived Au-Enriched TiO2 and TiO2-ZrO2 Photocatalysts and Their Examination in Photocatalytic Reduction of Carbon Dioxide
Matějová, Lenka ; Reli, M. ; Čapek, L. ; Matějka, V. ; Šolcová, Olga ; Obalová, L. ; Kočí, K.
Considering the aspects of preparation of gold-based photocatalysts and gold photocatalysis, it is worth a mention that it is more complicated issue than in the case of other noble metals due to the gold crystallinity. In this contribution some critical aspects of the gold photocatalysis will be discussed. Au-supported TiO2 and TiO2-ZrO2 photocatalysts and their pristine counterparts were prepared by using the sol-gel process controlled within reverse micelles environment and by impregnation under vacuum. All photocatalysts were characterized by OEA, ICP/MS, N2 physisorption, XRD, TEM/SEAD and UV-Vis. The performance of laboratory-prepared photocatalysts was examined in CO2 photocatalytic reduction and was compared with the catalytic performance of commercial TiO2 Evonic P25. Logically, the determined physicochemical and optical properties of photocatalysts were correlated with their catalytic performance and some interesting aspects of gold photocatalysis were revealed.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22013080910510 - PDF
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