Thursday
This is bloody clever:
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.
I came across this story while browsing through the weekly magazine, The Business (which has been re-launched from its previous format of a Sunday newspaper). The story says that the cement's amazing properties were discovered quite by accident and emerged from nanotechnology research undertaken by an EU-funded project (good grief, something positive via the EU, Ed). The Business article says that the photocatalytic cement building materials can get rid of up to 80 percent of air pollution.
The applications of the new kinds of materials technologies coming out from the worlds of nanotech and beyond are legion. I particularly like the idea that concrete, which normally turns a sort of gunky, greyish colour in Britain's damp climate, could stay a more pristine colour thanks to stuff like this. One of the reasons why so much modern architecture is so crap is not just the basic shapes of the buildings but the materials they are composed of.
I wonder whether it gets rid of grafitti, though.
(Update: another story on the subject)
It's a bit sparse on detail. What gasses are the nitrogen dioxide and carbon monoxide converted into exactly?
Posted by Freeman at December 14, 2006 09:17 PM
Yes, but when will they hybridize it with bendable cement?
Posted by Lexington Green at December 15, 2006 05:05 AM
And what exactly does this cement decay into having absorbed all these wonderful pollutants I wonder? I just bet that 30 years ago the EU would have extolled the virtues of a wonderful flame-retardant mineral known as asbestos ...
Posted by Julian Taylor at December 15, 2006 07:49 AM
There is also a matter of absorption saturation, which is not mentioned. I guess we'll have to wait for the specifics before any celebration.
Posted by The Wobbly Guy at December 15, 2006 09:09 AM
The term photocatalysis implies the cement doesn't absorb the pollutants, but rather greatly increases the rate of oxidation in the presence of light.
Posted by Eric at December 15, 2006 10:16 AM
Mr Taylor/Wobbly,
Read the piece - it's not absorption, it's photocatalysis -
just as some ovens self-clean because they have a catalytic (CeO2) coating which promotes oxidation of muck into CO2, this will probably promote NO->N2 and CO->CO2 (both thermodynamically favourable, but kinetically fairly slow) - just like a cat. converter promotes the 'water-gas' 2CO+2NO->2CO2+N2. [all N oxides are thermodynamically unstable wrt elements, because of the strength of the NN bond and lone-pair repulsion].
The cement won't be going anywhere, that's the whole point - its surface just acts as to reduce the energy barrier for certain pollutants to break down.
Oh and if we're to go OT,white asbestos (98% of production) isn't as bad as the vested interests would have you believe - remember there is a multi-billion pound legal industry set up to milk cash out of anyone who sits still long enough. The size differece between the dangerous, fine, amphibole asbestoses (Amosite and Crocidolite) and the stuff used in cloths and roofing sheets (Chrysotile) is huge - and the size is critical in determining the residence time in the lung. I am not aware (and I take an interest) of any research to have proven danger in chrysotile, despite the insistence by the HSE that it be treated the same in removal (even when fixed in cement).
Amphibole dangerous, chrysotile not really. But who cares when the lawyers and the removal contractors are making shedloads? A good scare always makes someone a lot of cash.
Posted by Chem Ed at December 15, 2006 10:17 AM
Chem Ed, I've been upset about the asbestos point because for very many years it's been know that white asbestos wasn't particularly harmful. Yet by insisting on combining all asbestos data, the true danger of brown, etc asbestos is concealed in the overall risk.
On the catalytic concrete, if it is used as pavement rather than retaining walls and other non-driven on construction, is'nt it difficult to keep it clean enough to work? It seems to me that there are a great many non-catalyzible things that will collect on it and interfer with the process. Or at least collect faster than they can be catalyzed. Oil drippings, tire marks, inert dirt, etc.
Also it seems glare will be enough of a problem that it may not be generally suitable for paving and highway retaining walls. But I could see a lot of it on the roofs of buildings. Especially in hotter climates where the added cooling benefit would be appreciated.
(I almost suggested that it would be ideal in tunnels because no glare and higher pollution problem. D'oh.)
Posted by Midwesterner at December 15, 2006 01:27 PM
Although tunnel use might not be so crazy if the artificial lighting was in the part of the spectrum that activates the catalyzing. It would depend on how efficient the process could be made, I guess.
Posted by Midwesterner at December 15, 2006 02:34 PM
