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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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Chemical sensor for the quality of the protective atmosphere of packaged foods
Filipi, Denisa ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
This thesis deals with optimizing compositions to prepare thin films for the quality sensor of the protective atmosphere of packaged food. This sensor is based on the detection of oxygen ingress into a modified atmosphere food package using a colour change of the sensor. Titanium dioxide dispersion was used as semiconductor and glycerol as sacrificial electron donor. The effect of the polymer matrix on the prepared thin films's appearance and on the reduction and reoxidation rates of the films was investigated. The thickness and rheological parameters of the selected sensor mixture were characterized and the stability of the thin films under visible light was monitored. The effect of oxygen concentration on the sensor's reverse oxidation kinetics was also studied. Furthermore, the selected sensor mixture print conversion from laboratory to operational scale was carried out. The prepared sensor thin films can be reduced by UV radiation with an intensity of 0.4 mW·cm2 in 35 s, and the color response of the film is visible even at low oxygen concentrations.
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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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