Research and treatment of air pollution by TiO2 nanomaterials
TiO2 has the form of a white, stable, unharmful, inexpensive powder. It exists in one of three types of representative crystal structures: rutile, anatase and brookite. Rutile - TiO2 has been used for hundreds of years in building materials as pigments for paints, chemical technology, drugs, cosmetics… Anatase - TiO2 has photo-catalyst activity, so it has been researched as one of the most promising choices for reducing harmful pollutants in the environment, especially killing bacteria, disease causing mould in rooms of houses, residing house, deodorizing of kakosmia in office, disposing such gases as NOx, SOx, VOCs,.... in the atmosphere.
Using photo-catalyst effects of nano TiO2, nanocomposite TiO2 (combination of nano TiO2 và apatite to make nanocomposit TiO2 material) to decompose air pollutants is considered as one of the important technical measurements in environment cleansing. This method has the advantage of low investment and operation cost in comparison to traditional refining method using absorber (it only uses sunlight, oxy and air humidity); the oxidizing process is conducted at normal temperature and pressure; most organic pollutants can be oxidized to be CO2 và H2O, finally.
In Vietnam, TiO2 nanomaterials have been paid much attention and researched resulting in encouraging achievements. Many TiO2 nanomaterials research works have been acclamed domestically and internationally. Especially, scientists have recently succeeded in researching some scientific products using TiO2 nanomaterials such as: active filters of photo-catalyst covered by TiO2 on silica cotton and on Al2O3 fibers in air cleaners; TiO2/Apatite paint to kill bacteria… This was achieved from the topic “Research and treat air pollution using nano TiO2/Apatite, TiO2/Al2O3 và TiO2/silica cotton paints” led by Doctor Nguyen Thi Hue, Insitute of Environment Technology. This topic was implemented over two years (2009-2010) with cooperation by the Insitute of Environment Technology and Institute of Applied Physics and Scientific instruments.
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Photo A: Air cleaner based on TiO2 photo-catalyst principle; Photo B: TiO2 air-cleaner screen – internal structure of equipment
Photo-catalyst active filter with internal air-cleaner screen made from TiO2/silica cotton and TiO2/Al2O3 under 20W light resource, wave length of 365nm, distance of 50cm, NO, CO gases with 5ppm concentration that were dismissed into the air only after 3h (TiO2/Al2O3 materials) and 2h (TiO2/SiO2 material) were completely eliminated; 100 microgam/m3 benzen, aldehit is also the same after 7-10h of reaction. TiO2/silica cotton and TiO2/Al2O3 have high, stable, persistent adhesion and actinic capacity equivalent to comparison models (France).
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Photo A: Al2O3 before TiO2 cover; Photo B: Al2O3 after TiO2 cover
TiO2/Apatite nano paint can treat air pollution such as eliminating kakosmia, killing bacteria, disease-causing mould in a hospital atmosphere, office, residing house or disposing harmful waste emissions caused by traffic activities. TiO2/Apatite nano paint was tested successfully in bacteria contaminated rooms, National Institute of Hygiene and Epidemiology and Vietnam - Cuba Friendship Hospital with positive results. After some hours coating paint on bricks, walls, fungus and bacteria almost completely disappeared.
Brick covered TiO2 paint to kill bateria, fungus, mould
Remaining bacteria after 3 hours on comparison model and TiO2/apatite paint model
New nanomaterials technology is easy to apply, generalized to recover a polluted air environment in densely-polluted cities. This will make important contributions to social-economic development and public health protection.
Translated by Hoang Lien
Link to Vietnamese version
