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Printed photoelectrochemical UV sensor
Vrbková, Kateřina ; Syrový, Tomáš (referee) ; Dzik, Petr (advisor)
This paper deals with the sensors, designed for ultraviolet light detection. There are many options in UV sensors construction. But in any case, there is a semiconducter used as a sensitive component. The most common photocatalyst is titanium dioxide. In electronic it is mainly used due to its suitable physical and chemical properties and good chemical stability. The aim of the work is preparation of gel electrolyte, which can close the electrical circuit between cathodic and anodic compartment and allows the passage of electrons. The hole first chapter is divoted to methods of UV sensors production, including electrochemical method on which is based our sensor.
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Study of Pharmaceuticals Degradationby Advanced Oxidation Processes
Bílková, Zuzana ; Čáslavský, Josef (referee) ; Beklová, Miroslava (referee) ; Zachariášová,, Milena (referee) ; Vávrová, Milada (advisor)
At present, the issue of occurrence of female sex hormones, estrogens and progestogens, in aquatic ecosystems is often discussed by experts and the general public. These substances of steroid structure can be difficult to remove completely by conventional wastewater and drinking water treatment technologies. In given context advanced oxidation processes based on in situ generation of highly reactive hydroxyl radicals can be a suitable technique. This thesis deals with the study of kinetics and degradation products of photocatalytic decomposition of seven female sex hormones (estrone, -estradiol, estriol, ethinylestradiol, diethylstilbestrol, progesterone and norethindrone). Experiments were conducted in a laboratory glass reactor, which was equipped with an energy efficient UV-A LED light source (365 nm emission wavelength) and an immobilised photocatalyst in a form of TiO2 five-layer film deposited on glass. Model samples of water with the initial hormone concentration of 1 mg·L-1 were used and the degradation process was monitored by an HPLC-MS method. In the given system all compounds of interest except estriol had very significant tendency to be adsorb. In the case of estriol the formal rate constant of photocatalytic decomposition was determined based on the Langmuir-Hinshelwood model for two different initial concentrations, 0.5527 hour-1 (1 mg·L-1) and 0.1929 hour-1 (5 mg·L-1), and by comparison of these values it was found that the higher degraded compound concentration, the slower decomposition (fivefold increase of the initial concentration resulted in the constant decrease to almost one-third). Moreover nine degradation products of estriol photocatalytic decomposition were recorded and their structure was designed based on mass spectra. In the second thematic part of the thesis attention was paid to development of a SPE-HPLC-MS method for simultaneous determination of female sex hormones in water ecosystems, with emphasis on an extraction part optimization. The final samples treatment process included besides extraction with Supel™ Select HLB 200 mg SPE cartridges also mechanical impurities removal, hormones extraction from solids trapped on filtration material, sample acidification and extract purification with Supelclean™ ENVI-Florisil® cartridges. Optimised method was used for determination of female sex hormones in two Brno rivers, Svitava and Svratka. In the most cases the concentration was below the detection or quantification limit.
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Optimalization of gel electrolyte for printed UV sensor based on photoelectrochemical cell
Vrbková, Kateřina ; Gemeiner,, Pavol (referee) ; Dzik, Petr (advisor)
This paper deals with the construction of photoelectrochemical cell, used for detection of ultraviolet radiation as a UV sensor. Photoelectrochemical cell consists of three layers, layer of photoactive semiconductor titanium dioxide, carbon electrodes and poly(vinyl alcohol) polymer electrolyte. The sensor layer enables the detection of UV radiation with the subsequent generation of photocurrent. Material printing techniques, such as screenprinting, pad printing and inkjet printing were used to produce the cell. Gel electrolyte was characterized by optical microscopy and rheometry. Sensor functionality was verified by use of electroanalytical techniques.
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Optimalization of gel electrolyte for printed UV sensor based on photoelectrochemical cell
Vrbková, Kateřina ; Gemeiner,, Pavol (referee) ; Dzik, Petr (advisor)
This paper deals with the construction of photoelectrochemical cell, used for detection of ultraviolet radiation as a UV sensor. Photoelectrochemical cell consists of three layers, layer of photoactive semiconductor titanium dioxide, carbon electrodes and poly(vinyl alcohol) polymer electrolyte. The sensor layer enables the detection of UV radiation with the subsequent generation of photocurrent. Material printing techniques, such as screenprinting, pad printing and inkjet printing were used to produce the cell. Gel electrolyte was characterized by optical microscopy and rheometry. Sensor functionality was verified by use of electroanalytical techniques.
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Printed photoelectrochemical UV sensor
Vrbková, Kateřina ; Syrový, Tomáš (referee) ; Dzik, Petr (advisor)
This paper deals with the sensors, designed for ultraviolet light detection. There are many options in UV sensors construction. But in any case, there is a semiconducter used as a sensitive component. The most common photocatalyst is titanium dioxide. In electronic it is mainly used due to its suitable physical and chemical properties and good chemical stability. The aim of the work is preparation of gel electrolyte, which can close the electrical circuit between cathodic and anodic compartment and allows the passage of electrons. The hole first chapter is divoted to methods of UV sensors production, including electrochemical method on which is based our sensor.
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|
|
Study of Pharmaceuticals Degradationby Advanced Oxidation Processes
Bílková, Zuzana ; Čáslavský, Josef (referee) ; Beklová, Miroslava (referee) ; Zachariášová,, Milena (referee) ; Vávrová, Milada (advisor)
At present, the issue of occurrence of female sex hormones, estrogens and progestogens, in aquatic ecosystems is often discussed by experts and the general public. These substances of steroid structure can be difficult to remove completely by conventional wastewater and drinking water treatment technologies. In given context advanced oxidation processes based on in situ generation of highly reactive hydroxyl radicals can be a suitable technique. This thesis deals with the study of kinetics and degradation products of photocatalytic decomposition of seven female sex hormones (estrone, -estradiol, estriol, ethinylestradiol, diethylstilbestrol, progesterone and norethindrone). Experiments were conducted in a laboratory glass reactor, which was equipped with an energy efficient UV-A LED light source (365 nm emission wavelength) and an immobilised photocatalyst in a form of TiO2 five-layer film deposited on glass. Model samples of water with the initial hormone concentration of 1 mg·L-1 were used and the degradation process was monitored by an HPLC-MS method. In the given system all compounds of interest except estriol had very significant tendency to be adsorb. In the case of estriol the formal rate constant of photocatalytic decomposition was determined based on the Langmuir-Hinshelwood model for two different initial concentrations, 0.5527 hour-1 (1 mg·L-1) and 0.1929 hour-1 (5 mg·L-1), and by comparison of these values it was found that the higher degraded compound concentration, the slower decomposition (fivefold increase of the initial concentration resulted in the constant decrease to almost one-third). Moreover nine degradation products of estriol photocatalytic decomposition were recorded and their structure was designed based on mass spectra. In the second thematic part of the thesis attention was paid to development of a SPE-HPLC-MS method for simultaneous determination of female sex hormones in water ecosystems, with emphasis on an extraction part optimization. The final samples treatment process included besides extraction with Supel™ Select HLB 200 mg SPE cartridges also mechanical impurities removal, hormones extraction from solids trapped on filtration material, sample acidification and extract purification with Supelclean™ ENVI-Florisil® cartridges. Optimised method was used for determination of female sex hormones in two Brno rivers, Svitava and Svratka. In the most cases the concentration was below the detection or quantification limit.
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