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What is Photocatalyst Photo-Catalysis is defined as "acceleration by the presence of as catalyst". A catalyst does not change in itself or being consumed in the chemical reaction. This definition includes photosensitization, a process by which a photochemical alteration occurs in one molecular entity as a result of initial absorption of radiation by another molecular entity called the photosensitized. Chlorophyll of plants is a type of Photocatalyst. Photocatalysis compared to photosynthesis, in which chlorophyll captures sunlight to turn water and carbon dioxide into oxygen and glucose, photocatalysis creates strong oxidation agent to breakdown any organic matter to carbon dioxide and water in the presence of Photocatalyst, light and water. Titanium Dioxide structured in anatase form is the most common Photocatalyst. It has the following advantage:
A promising approach for remediation of air quality contaminants is to employ Photocatalyst that oxidize these compounds. By definition, Photocatalyst is a catalyst that accelerates photoreaction. When
Photocatalyst is exposed to
light in the presence of water vapour, two highly reactive substances
are formed: hydroxyl radicals [OH] and a super-oxide anion [O2-1].
It allows the oxidation of airborne VOC's and toxic organic matter into carbon dioxide and
water at room temperature with UV or near-UV light source.
It does not need a special energy and
use only clean energy in ordinary life. Specific titanium dioxide
has strong photo catalyst reaction. It has strong oxidation and
decomposition strength.
Photocatalyst has the following advantages over any current air purification technologies:
Titanium dioxide,
also known as titania, is the naturally occurring oxide of
titanium, chemical formula TiO2. Approved by the food testing
laboratory of the United States Food and Drug Administration
(FDA), Titanium Dioxide is considered a safe substance and
harmless to human. It is commonly used in paint, printing ink,
plastics, paper, synthetic fibers, rubber, condensers, painting
colors and crayons, ceramics, electronic components along with
food and cosmetics. Many studies have been published on the use of
titanium dioxide as a Photocatalyst
Titanium Dioxide molecules contain electrons that are confined to relatively narrow energy bands. The band of highest energy that contains electrons is the valence band, while the band lying above the valence band, i.e. the conduction band, has very few electrons. The difference in energies between the highest energy of the valence band and the lowest energy of the conduction band is termed the band gap energy. When a semiconductor absorbs a photon of energy equal to or greater than its band gap, an electron may be promoted from the valence band to the conduction band leaving behind an electron vacancy or “hole” in the valence band. If charge separation is maintained, the electron and the hole may migrate to the catalyst surface where they participate in redox reaction with sorbed species
Strong Oxidation Power Hydroxyl radicals are among the strongest oxidizing species, even much stronger than chlorine, ozone, and peroxide. They act as very powerful disinfecting agents by oxidizing the cells of microorganisms, causing rupture and leakage of vital composition.
The hydrophilic nature
of titanium dioxide, coupled with the gravity, will enable the dust
particles to be swept away following the water stream, thus making
the product self-cleaning. When the surface of Photocatalytic film is exposed to light, the contact angle of the Photocatalyst surface with water is reduced gradually. After enough exposure to light, the surface reaches super-hydrophilicity. In other words, it does not repel water at all, so water cannot exist in the shape of a drop, but spreads flatly on the surface of the substrate. And the water took the form of a highly uniform thin film, which behaves optically like a clear sheet of glass. Most of the exterior walls of buildings become soiled from automotive exhaust fumes, which contain oily components. When the original building materials are coated with a Photocatalyst, the dirt on the walls will wash away with rainfall, keeping the building exterior clean at all times.
True dispersion of Nano-Sized Particles Dispersing Photocatalyst Titanium Dioxide in solution has always been a challenge. Traditional manufacturing method of Photocatalyst Titanium Dioxide used strong acid or solvent to dissolve Titanium Dioxide in liquid form. But these Photocatalyst products tend to be highly acidic and contain high level of Volatile Organic Compound. Another disadvantage of this traditional Photocatalyst titanium dioxide solution is that Titanium Dioxide in the solution sometimes forms white deposit and renders the solution to be unusable. ECS Photocatalyst Products are truly the breakthrough in dispersing Nano-sized Titanium Dioxide in aqueous form. Using patented manufacturing process and chemical formula; ECS Photocatalyst products are neutral and contain no VOC. Titanium Dioxide particles in our products would not form any deposit which prolongs left expectancy of the product.
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©2005 Environmental Coating
Solutions.,
Images & Text may not
be used without permission.
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for the
decomposition of organic compounds. After illuminated by light,
titanium dioxide produces hydroxyl radicals, which react with the
organic matters in the air to form non-toxic inorganic matters.
