ABSTRACT
A particular technique or technology becomes economical when marketable products can be isolated from the remediation process itself. The use of photocatalysis for the remediation of polluted air is relatively new and started only in the 1990s. The principles of electrochromic and photocatalysis were used simultaneously. For obvious reasons, in the case of abatement of air pollution, it is almost mandatory to immobilize the photocatalyst and the source of light should be so positioned that proper irradiation is attained. Flat plate reactors accommodate the photocatalyst support, which is also flat and usually made of glass or metal, and the polluted stream flows parallel and on the top of the photocatalyst support. TiO2 is the most used photocatalyst even for air pollution control. TiO2-cement composites show a synergy between cementitious material and TiO2, which makes cement an ideal substrate for environmental photocatalysis. Photocatalytic building materials are commercially used for self-cleaning and air pollution control in different countries.
