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Last Updated: Friday, 10 February 2006, 09:43 GMT
Self-cleaning bathroom on the way
By Marina Murphy

Taps (BBC)
Few of us enjoy the weekly blitz on the bathroom
Nanotechnology may yet rescue us from the drudgery of the weekly ritual of blitzing the bathroom.

Scientists in Australia have developed an environmentally friendly coating containing special nanoparticles that could do the job of cleaning and disinfecting for us.

"If you have self-cleaning materials, you can do the job properly without having to use disinfectants and other chemicals," says researcher Rose Amal at the Particles and Catalysts Research Group, University of New South Wales, where the coating is being developed.

Previously self-cleaning materials were limited to outdoor applications because ultraviolet light was required to activate the molecules in the coatings.

Less time cleaning the bathroom is rather appealing
Mary Taylor, Friends of the Earth
These surfaces contain tiny particles of titanium dioxide, which become excited when they absorb ultraviolet light with a wavelength of less than 380 nanometres.

Light activated

This gives the particles an oxidizing ability stronger than chlorine bleach. The excited particles can break down organic compounds and kill bacteria.

The new coating contains modified particles of titanium dioxide, which are doped with other cations like iron or vanadium and anions like oxygen, nitrogen or carbon.

This coating can absorb light at the higher wavelengths in visible light, such as the bathroom light.

E. Coli (BBC)
The coating can kill bacteria such as E. coli
Lab experiments revealed the surface of coated glass could kill the bacteria E. coli (Escherichia coli) and degrade volatile organic compounds in visible light.

The oxidising properties also mean fungus cannot grow on the surface. And because the coating is hydrophobic - it does not like water - the water simply slides away carrying any dirt with it, rather than gathering as droplets.

Using the coating in baths and sinks would not pose any problems with skin irritation, according to Amal.

"When the bath is filled, the water would attenuate the light so I don't think the surface would activate. It will only be active if the light can reach the surface," she says.

Possible disadvantages

Friends of the Earth spokesperson Mary Taylor said that if materials like this could prolong the lifetime of an object, this would be an advantage in environmental terms.

But she warned: "Such a hi-tech material might have some disadvantages.

"We would have to consider, for example, whether the material could be recycled or disposed of safely, and how much more energy went into production of the raw materials and its manufacture."

However, she added: "Less time cleaning the bathroom is rather appealing, and there might be some special uses, maybe in hospitals, where such materials could be a boon."

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