Italian Cement absorbs pollutants

[SteveGrenard]

Once in a while an invention comes along that benefits society, here's one from Italy:

New kind of cement absorbs pollution
From UPI:

An Italian company has begun marketing a cement that is capable of absorbing pollution from vehicles.

Italcementi, which spent 10 years developing its TX Active, said the building material is capable of reducing urban pollution by more than 40 percent, the Italian news agency ANSA reported Tuesday.

Tests on a road near Milan showed TX Active cut the level of nitrogen dioxide and carbon monoxide by as much as 65 percent.

http://www.physorg.com/news67012896.html

I wonder what happens to the pollutants when the cement can absorb no more or when the cement is demolished and taken down. Beyond these back-end concerns this does seem like a good idea until we no longer have to concern ourselves with automobile emissions as they present occur.

 

[Ziggurat]

I wonder what happens to the pollutants when the cement can absorb no more or when the cement is demolished and taken down. Beyond these back-end concerns this does seem like a good idea until we no longer have to concern ourselves with automobile emissions as they present occur.

"It functions via a chemical process called photocatalysis, whereby sunlight triggers a chemical reaction when titanium dioxide on the surface of the cement comes into contact with pollutants in the air."

From that quote, I'm guessing that this stuff doesn't actually capture and store the pollutants, but acts like a catalyst to convert the NO2 into N2 and O2, and the CO into CO2. If that's the case, then it won't necessarily run out, and there's no back-end problems either. Of course, I suspect that accumulated dirt on the surface over the years will likely impede its effectiveness, but that's a different problem.

 

[AgeGap]

I have a white acrylic paint that is white because of titanium dioxide. Also isn't titanium dioxide in toothpaste. Why not just paint the concrete white?

 

[leon_heller]

It would take a lot of energy and hence CO2 to manufacture the TiO2 they use in the cement. That might be worse for the environment than the reduction in NO2 and CO.

Leon

 

[Ziggurat]

I have a white acrylic paint that is white because of titanium dioxide. Also isn't titanium dioxide in toothpaste. Why not just paint the concrete white?

If it's embedded in acrylic (or any other paint binder) it might not be able to act as a catalyst. I think the trick is getting it fixed in place but exposed to air and sunlight at the same time.

 

[Ziggurat]

It would take a lot of energy and hence CO2 to manufacture the TiO2 they use in the cement. That might be worse for the environment than the reduction in NO2 and CO.

Leon

NO2 and CO are harmful for humans to breath. CO2 is not (until you get to MUCH higher concentrations than can be found outdoors, even around highways). There are definite reasons to prefer CO2 to CO or NO2.

 

[casebro]

I wonder if Titanium even acts a a catalyst for those reactions- and at room temperature? Or does Titanium DiOxide even act as a catalyst at all, since the T is bound pretty solidly to the Os?

The chemists are bound to arrive here shortly.

 

[leon_heller]

NO2 and CO are harmful for humans to breath. CO2 is not (until you get to MUCH higher concentrations than can be found outdoors, even around highways). There are definite reasons to prefer CO2 to CO or NO2.

But they degrade quickly. CO2 doesn't.

Leon

 

[leon_heller]

TiO2 is a catalyst for that type of reaction:

http://www.sachtleben.de/include/3_1_2_0_EN.html

Leon

 

[elgarak]

This idea is pretty old. It was originally published in 1969 by A. Fujishima. The link is to the abstract of the original Japanese publication, though.

I once attended a talk by Fujishima, in 1999 or 2000, where he outlined all kinds of applications for nanocrystalline TiO2, including the photocatalytic effect of removing pollutants from the air.

Actually, I'm a bit surprised how long it took for such products to come out. When you heard Fujishima, such products should be just around the corner. So to me, this is not really new. Just shows how long it takes from idea to product.

 

[shadron]

But they degrade quickly. CO2 doesn't.

Leon

Not quickly enough. While they're there, NO2 (and sulfur) are easily converted into acids which erode and corrode infrastructure (bridges, buildings, sidewalks and road surfaces), kill plants and cause irritation and damage to lung tissue. CO replaces O2 in the blood and locks up blood's ability to transport oxygen to tissues. CO2 is definitely more to be liked than these other two are. In any case the amounts are miniscule compared to those dumped in the atmosphere by a coal power plant, or even by that auto fuel that does get completely burned into CO2 directly. Also, you can be sure that CO doesn't degrade into elemental carbon.

Sounds like a heck of an idea if it is efficient enough. 40% is likely worth it.

 

[Evilgiraffe]

I have a white acrylic paint that is white because of titanium dioxide. Also isn't titanium dioxide in toothpaste. Why not just paint the concrete white?

If it's embedded in acrylic (or any other paint binder) it might not be able to act as a catalyst. I think the trick is getting it fixed in place but exposed to air and sunlight at the same time.

I think it's a question of surface area. I believe most catalytic applications of TiO₂ are based on nano-crystalline titania which will have a much larger surface area than the larger crytals used for white pigments.

That said, I think there will be catalytic activity on white pigment particles. It'll just be at such a minimal level as to be un-noticeable.