SELF-CLEANING GLASS and ELECTROCHROMIC GLASSUNIVERSITÀ DEGLI STUDI DI LECCE
Corso di laurea in Ingegneria dei Materiali
A.A. 2001/2002
Scienza e Tecnologia dei Materiali Ceramici Professore
Dott. Antonio Licciulli Studente
Daniela Lisi
SELF-CLEANING GLASS and ELECTROCHROMIC GLASS
UNIVERSITÀ DEGLI STUDI DI LECCE
Corso di laurea in Ingegneria dei Materiali
A.A. 2001/2002
Scienza e Tecnologia dei Materiali Ceramici Professore
Dott. Antonio Licciulli Studente
Daniela Lisi
SELF-CLEANING GLASS
SUMMARY
HISTORY TITANIUM DIOXIDE SELF-CLEANING SURFACE PHOTOCATALYSIS HYDROPHILICITY SUPER-HYDROPHILICITY SELF-CLEANING WINDOWS
HISTORY
The late 1960s: the University of Tokyo research photoelettrochemical solar cells. The solid-state photovoltaic device has become the technology of choice.
1972: Fujishima and Honda discovered the photocatalytic splitting of water on TiO2 electrodes without using electricity.
1977: Professor Allen J. Bard and co-workers at the University of Texas first examined the possibilities of using TiO2 to decompose cyanide in water. Many important fundamental results concerning TiO2 photocatalytic reaction have been clarified by such intensive works.
The late 1990s: Pilkington, PPG, SSG patent SELF-CLEANING windows.
TITANIUM DIOXIDE
SELF- CLEANING and ANTIFOGGING functions PHOTOCATALYST HYDROPHILIC
White pigment in paints, cosmetics and foodstuffs. Semiconductor transparent in the visible region of the
spectrum. Low costs material. Chemically inert, non-toxic, biocompatible. TITANIUM DIOXIDE
SELF-CLEANING SURFACE
TO CLEAN SURFACE OF BUILDING MATERIALS CAUSES: Considerable trouble. High consumption of energy. Chemical detergents. High costs
TO REALIZE SELF-CLEANING MATERIAL SURFACES THERE ARE THREE PRINCIPAL WAYS : Super-hydrophobicity. Photocatalysis. Super-hydrophilicity and hydrophilicity SELF-CLEANING SURFACE
HYDROPHOBICITY
Hydrophobic materials ("water hating") have little or no tendency to adsorb water and water tends to "bead" on their surfaces (i.e., discrete droplets). Hydrophobic materials possess low surface tension values and lack active groups in their surface chemistry for formation of "hydrogen-bonds" with water.
CONTACT ANGLE HYDROPHOBICITY For a given droplet on a solid surface: the contact angle is a measurement of the angle formed between the surface of a solid and the line tangent to the droplet radius from the point of contact with the solid.
HYDROPHOBICITY
SUPER-HYDROPHOBICITY
The LOTUS EFFECT
PHOTOCATALYSIS
WHAT IS IT? The acceleration of the rate of a photoreaction by the presence of a catalyst (semiconductor particle).
WHAT IS a SEMICONDUCTOR SOLID? PHOTOCATALYSIS
HOW DOES PHOTOCATALYTIC SEMICONDUCTOR WORK? PHOTOCATALYSIS
TiO2 AS PHOTOCATALYST
OXIDATION-REDUCTION REACTION ON THE SURFACE OF TIO2 TiO2 AS PHOTOCATALYST
IT IS COMPETITIVE BECAUSE: A low-cost material is used as photocatalyst. The reaction is quite fast at mild operating conditions
(room temperature, atmospheric pressure). A wide spectrum of organic contaminants can be
converted to water and CO2. No chemical reactants must be used and no side
reactions are produced. TiO2 AS PHOTOCATALYST
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