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Smog Busting Paint Breaks Down Noxious Gasses
jlechem writes "New Scientist is reporting a story about a new paint that can absorb noxious gas. According to the article the new paint is called Ecopaint. The substance is designed to reduce levels of the nitrogen oxides, collectively known as the NOx gases, which cause respiratory problems and trigger smog production. The paint's base is polysiloxane, a silicon-based polymer. Embedded in it are spherical nanoparticles of titanium dioxide and calcium carbonate 30 nanometres wide. Because the particles are so small, the paint is clear, but pigment can be added. The first paint to go on sale will of course be white."
According to the article, after the carbonate runs out after about 5 years in a heavily polluted city, "the titanium dioxide will continue to break down NOx, but the acid this produces will discolour the paint."
Doesn't sound very good.
HCG 50a = 2MASX J11170638+5455016
11h17m06.4s +54d55m02s
In goes noxious gas (pun intended) and out comes a weak acid. Put a ring of limestone gravel or pavers around the base of the building and even that would be neutralized.
Of course the bigger question is if this paint and other materials like it are cheaper then catching the gasses closer at their sources, or at least ensuring those sources aren't so close to folk's lungs and other living creatures not appreciative of such.
I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
The Titaninum oxide is a catalyst, so it is not consumed. The calcium carbonate is just there to neutralize the acid that is produced on the catalyst. So, the paint will never get sauruated with acids. I'll bet that they catalyst will keep working without the calcium carbonate & that the resulting nitric acid will just wash off, probably into some nearby concrete, which aso has a lot of calcium carbonate to neutralize the nitric acid. Besides, a little nitric acid isn't all that bad as a pollutant... you can safely wash it down the drain.
Think global, act loco
The titanium dioxide is a catalyst. It catalyzes a reaction between NO2 and water to produce nitric acid, HNO3. This reacts with calcium carbonate, CaCO3 (basically chalk) in the paint to produce water, carbon dioxide, and calcium nitrate:
CaCO3 + 2HNO3 -> H2O + CO2 + Ca(NO3)2.
The titanium dioxide is not consumed in the reaction, but the chalk is, and when it runs out, your paint fills up with nitric acid, which is not good. However, the reaction that causes the formation of nitric acid happens at a slower rate on its own, it is one source of acid rain.
Calcium nitrate is not noxious; it's basically fertilizer. However, too much nitrate runoff will cause problems with excessive algae growth in water, which can drop the oxygen level low enough to kill fish. Just the same, there's a lot more nitrate runoff from farmers and lawns than you're likely to get from this stuff.
It's interesting to note that an experimental technology involving the use of very fine titanium dioxide powder has been selected to purify water. The water is recirculated in a fountain so that it is exposed to lots of light- ultraviolet catalyzes the decomposition of select contaminants in the presence of the otherwise inert titanium dioxide, producing non-toxic byproducts. It's CHEAP, safe, and effective- but nobody wants to do it, since the technology is still in the experimental phase. Company XYZ isn't willing to pay $millions to try it when there are proven (if more expensive) techniques for doing essentially the same thing.
And I'm a firefighter, too. And a chemist. Too many hats to wear these days.