The photocatalyst is an environmental clean-up material that arises on the surface when the light such as the sunlight and fluorescent lamps hit, and can remove an organic compound such as odors and bacilli. The photocatalyst works by the following principles.
　
Principles
　

　

1.Exposure to ultraviolet rays (UV)
The electron jumps up from the surfece when light(Ultoraviolet rays) が hits the photocatalyst (titanium dioxide). At this time the hole which the electron jumped up from is called the positive hole, and has worn the charge of the plus.

原理説明図 　
　

2. OH radical appearance
The positive hole has the strong oxidation power and take the electron from OH-(hydroxide ion) in water. At this time OH-, that was taken the electron, becomes OH radical of very unstable condition.
　
3. Decomposition of organic compound
OH radical takes the electron by the strong oxidation from the nearby organic compaound to become stable oneself. In this way the organic compound is decomposed by loss of the electron and finally becomes carbon dioxide and water, and emanated to an atmosphere.
　
　
The photocatalyst works by the power of light. Why is it necessary that the light sources are ultraviolet rays?
　
About light...
　
　

TiO2 is a semiconductor which turns to the high-energy state by receiving the light energy, and releases the electron(e-) from its illuminated surface. If the energy received at this stage is high enough, all electrons that were initially located in the so- called " the valence bond" jump up to "the conduction band" all at once.

Thus, the energy that makes electrons jump up is provided by the light and this light energy is related to the light's wavelengths.
Therefore, calculating from the hight that the electrons have to jump up , this light should have the same wavelength as ultraviolet light.

　
　
　
　
The photocatalyst functions are the next 5 items mainly. 　
　
Primary 5 Utilization

　

 　
Removal of harmful substance such as NOx and SOx, formaldehyde in the atomosphere.
Adosorption and decomposition of odor such as acetaldehyde, ammonia, hydorogen sulfide.
Decomposition and removal of the volatility organic chlorine compound such as tetrachloroethylene and trichloroethylene that are the pollutant in the water.

Anti-Bacteria

Clean environment by the anti- bacteria and sterilization actions.
Dirtiness prevention of the bailey and floor.

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5つの機能


　

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