Testing of Photocatalytic Activity of Self-Cleaning Surfaces

Urška Lavrenčič Štangar; Marko Kete; Urh Černigoj; Vilma Ducman

doi:10.4028/www.scientific.net/AST.68.126

Paper Titles

Quantitative Infrared Thermography (IRT) and Holographic Interferometry (HI): Nondestructive Testing (NDT) for Defects Detection in the Silicate Ceramics Industry
p.102

Fast Firing of Glazed Tiles Containing Paper Mill Sludge and Glass Cullet
p.108

Kinetics Study on Controlled Crystallization of a Ca₂ZnSi₂O₇ Phase in Materials Obtained from Vitrification of Metallurgical Slag and Recycled Soda Lime Glass
p.114

Sintering Behaviour of Ceramics Containing Paper Sludge, Glass Cullet and Different Types of Clayey Materials
p.120

Testing of Photocatalytic Activity of Self-Cleaning Surfaces
p.126

Nano-Structured Glassy and Ceramic Surfaces: Development of "Active" Materials for an Innovative Approach to Building Industry
p.135

Nano-Sized Metal Oxide Modification Applied in Microfiltration Membrane Technology
p.145

Effect of Nanosized TiO₂ on Nucleation and Growth of Cristobalite in Sintered Fused Silica Cores for Investment Casting
p.153

Almost Complete Nitridation of Mesoporous Silica to Mesoporous Silicon (Oxy)Nitride with Ammonia
p.159

HomeAdvances in Science and TechnologyAdvances in Science and Technology Vol. 68Testing of Photocatalytic Activity of...

Testing of Photocatalytic Activity of Self-Cleaning Surfaces

Abstract:

Due to relatively successful application of TiO2 photocatalysis in the field of self-cleaning surfaces, a reliable and appropriate quantitative method for determining the self-cleaning efficiency of the products (photocatalyst films on different supports) should be widely recognized and established. Currently, the two standard methods are based on photobleaching of methylene blue aqueous solution in contact with thin solid catalyst layer, and on photodegradation of a solid fatty deposit (e.g. stearic acid) over catalyst layer followed indirectly by water contact angle (CA) measurements. Another method proposed recently is based on the entrapment of an organic dye in a solid polymer matrix deposited over the photocatalyst layer. Upon illumination, the dye (e.g. resazurin) is reduced by the photogenerated electrons to the form of a different colour or to the bleached form. Recently, a new method for determination of self-cleaning activity of photocatalytic surfaces was developed in our laboratory. It is based on the deposition of a transparent solid layer comprising terephthalic acid over the photocatalytic surface. When such a system is irradiated, among the other degradation products also a hydroxyterephthalic acid is formed due to a reaction between photoexcited TiO2 and terephthalic acid. Hydroxyterephthalic acid is a highly fluorescent molecule and can be easily detected by HPLC-FLD or spectrofluorimeter. Many different samples were tested using this method and using the standard method based on photodegradation of a solid fatty deposit over the catalyst layer. Regarding the sample (substrate) type, the focus was given to the self-cleaning ceramic tiles coated with TiO2-SiO2 thin films that were produced in cooperation with the major manufacturer of floor ceramic tiles in Slovenia, Martex d.o.o.. In case of self-cleaning ceramics and some other sample types, the advantages of the new method over standard methods were highlighted and critically evaluated.