What is photocatalyst?
Photocatalyst is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible light (400 – 750 nm) or infrared radiation (750 – 2500 nm). A catalyst does not change in itself or being consumed in the overall 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.
Photocatalyst accelerates the oxidation process in the atmosphere and decomposes any air borne toxic organic matter.
There are various materials that show photocatalytic capability, and titanium dioxide (TiO2) is said to be the most effective.
When photocatalyst is exposed to light in the presence of water vapor, two highly reactive substances are formed: hydroxyl radicals [OH] and a superoxide anion [O2-1]. It allows the oxidation of airborne VOCs and toxic organic matter into carbon dioxide and water at room temperature with 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.
A promising approach for remediating volatile organic compounds or VOCs is to employ photocatalyst that oxidize these compounds. It is a substance that facilitates chemical reactions by photo-irradiation without becoming transformed:
Toxic VOC + Light + Water + Photocatalyst = Non-Toxic inorganic Gas + Photocatalyst
Photocatalyst has the following advantages over any current air/water purification technologies:
- Real destruction of pollutant rather than a simple transfer on a substrate
- Degradation of pollutant at ambient temperature and pressure
- Build with easily available materials and by mean of well-known techniques
- Economical, cheap and low energy consumption
- Adapted for a large range of pollutant (VOC, bacteria, mold)