Analysis of the Photocatalytic Activity of TiO2 Coating on a Glass as a Criterion of Its Ability to Self-cleaning

Abstract

The object of research is the process of photocatalytic degradation of methylene blue on glass coated with titanium oxide under the influence of ultraviolet radiation (UV radiation). The study aims to indirectly assess the ability of glasses to self-clean. An axiomatic assumption is made about the correlation between self-cleaning ability and photocatalytic activity.The proprietary photocatalytic reactor is used. This is a cylindrical quartz glass cavity in the form of a glass, on the inner surface of which a photocatalytic coating of titanium oxide is preliminarily applied. The cavity of the glass is filled with a solution of methylene blue. Externally, the glass is irradiated with a mercury-quartz lamp. UV radiation passes unhindered through quartz glass and activates photocatalytic coatings on the back side. To activate the process requires the participation of atmospheric oxygen. To do this, the solution is bubbled with air from a perforated annular tubular collector located at the bottom of the glass.The solution of methylene blue after various exposure times is subjected to spectral analysis. The kinetics of dye degradation is estimated by the photocolorimetric method with a decrease in the intensity of the characteristic absorption band of methylene blue. The bleaching process is clearly demonstrated on the color chart.The novelty of the proposed scheme for the functioning of the photocatalytic reactor is that UV radiation activates the coatings acting on it from the side of the inner interface: quartz glass coating. Electron-hole pairs migrate to the surface and, under conditions of contact with oxygen, carry out the photocatalysis of the model solution. Such a design of the photocatalytic reactor device compares favorably with the known ones because UV radiation does not pass through the studied model fluid. This excludes the possibility of their interaction, may introduce an error in the final results.