13 August 2008

NOxious fumes

Nitrogen oxides, or NOx, are highly reactive gases that are emitted from cars and other machinery, contributing to a range of environmental hazards. NOx-attributed detriments include:

  • Smog
  • Acid rain
  • Air particulates (not so great for us lung-breathers)
  • Water pollution
  • Climate change
  • Biological mutations via chemical reactions
[Source: US EPA]

Well in Madrid, Spain, they've figured out a way to help contain NOx emissions right where they occur the most -- on the road. The newly laid asphalt paving Spanish streets includes a mix that includes titanium dioxide called "noxer." Titanium dioxide is a photocatalyst that uses sun to capture NOx and render the oxides harmless, leaving only nitrate ions. These ions are then either washed away by rain or are stored within the pavement.
[Image: Ángel Casaña]

The city claims that up to 90% of NOx can be recaptured on a sunny day.

How noxer works:

[Source: Wikipedia]

1. Ultraviolet radiation is absorbed by the titanium dioxide, which causes the photolysis of water into superoxide ions and hydroxyl radicals.
2. Nitrogen oxides react with the superoxide ions and the hydroxyl radicals to form nitrate ions.
3. The nitrate ions are absorbed into the block and form stable compounds.

[Europa Press via autobloggreen]

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