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Self-Cleaning via Titanium Dioxide
Jeremy Faludi, 18 Jun 04

rutile.jpgTitanium dioxide is a white powder, something we eat and see frequently as a whitener for paint, processed food, toothpaste, and many other products. However, it turns out that TiO2 is also a strong photocatalyst--so when it's in the sun, organic compounds (e.g. dirt, mold, mildew, bacteria) that touch it break down, without consuming the TiO2 because it's just a catalyst in the reactions. Also, it's extremely hydrophilic, so water hitting it forms a smooth sheet instead of tiny droplets, and that sheet gets under dirt to lift it off the surface and get it easily washed away. The combination of these effects makes TiO2 self-cleaning to a large extent, and it can be applied in microscopically thin coatings to building materials, glass, or even fabrics. As Nature reports, scientists in Hong Kong are developing dirt-resistant clothing with it, and a Japanese company named Toto already has ceramic tiles on the market using it. As the National Institute of Health's Environmental Health Perspectives reports,


...self-cleaning ceramic tiles...achieve a 99.9% bacterial kill rate within one hour for such strains as penicillin-resistant Staphylococcus aureus and Escherichia coli.

Japan's Mitsubishi Materials Corporation has developed a paving stone it calls "Noxer" that uses the catalytic properties of TiO2 to remove nitrogen oxide (NOx) from the air, breaking it down into more environmentally benign substances...[namely] nitric acid ions. These ions can then be washed away by rainfall or neutralized by the alkaline composition of the concrete. Results of these tests showed an 80% NOx removal rate based on an intensity of UV light of 1-12 watts per square meter (W/m2) (the UV intensity of direct sunlight in summer is 20-30 W/m2, compared to 1 W/m2 on a cloudy winter day).

...Other experiments with TiO2 involve removing the ripening hormone ethylene from areas where perishable fruits, vegetables, and cut flowers are stored; stripping organic pollutants such as trichloroethylene and methyl-tert-butyl ether from water; and degrading toxins produced by blue-green algae. It remains to be seen, however, whether the formation of undesirable intermediate products during these processes outweighs the benefits offered by TiO2's photocatalytic properties.

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Comments

Titanium Dioxide coated light bulbs were just featured on Kevin Kelly's Cool Tools site. They eliminate odors.

http://www.kk.org/cooltools/archives/000467.php


Posted by: Monty Zukowski on 18 Jun 04

Time to watch "The Man in the White Suit" with the great Alec Guinness again.


Posted by: gmoke on 18 Jun 04

Experience clean, germ-free air in your office or home just by turning on the lights. Get rid of pet odors. Bacteria. Dust mites. O.ZONELite¬ô is the first light bulb to actually kills airborne bacteria, germs, fungi, mold, mildew, smoke and odors. At only 23 watts, the bulb emits as much illumination as a 100-watt incandescent bulb, making it energy efficient as it neutralizes smoke and odors. Over the life of the lamp it saves $50.00 and actually pays for itself.

The bulb is coated with titanium dioxide (TiO2). As air passes through, the result is oxidation, which attacks and destroys microbes by disintegrating their DNA. The reaction also kills dust mites and mold.

"Unlike air sprays that just mask the odors, the O.ZONELite actually eliminates it and eliminates potentially harmful bacteria," said David deMartino O.ZONELite CEO.

According to deMartino and O.ZONE LitePresident William C. Stone, O.ZONELite uses no toxic chemicals and the product is more cost-effective than HEPA filters and air ionizers, which only trap airborne particles.

deMartino and Stone introduced the bulbs to the United States market in December 2003 and report that O-ZONE.Lites are all ready in great demand. "We have a product that is an air purification system, but you would never know it by the look. Our system looks like an ordinary spiral light bulb. But, it does much, much more at a far lower cost," said deMartino.

O.ZONELite is headquartered in Deerfield Beach, Florida and the bulbs may be purchased at the company web site and also by calling the toll-free number (800) 494-8292.


Posted by: Linda on 1 Jul 04



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