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Dutch Town Lays Air-Purifying Concrete
eldavojohn writes "In an effort to combat air pollution, a Dutch town has paved some of its streets with air-purifying concrete. It contains a titanium dioxide-based additive that utilizes sunlight to turn car exhaust into harmless nitrates. It was shown to do this in a lab and now the scientists are interested in just how much this will affect the air quality around the road. They will sample the air quality by a normal road and by this newly paved one."
All passive filters I know require replacement because they get clogged, or the active elements eventually decay. Beyond making jokes about swapping the church bricks five years from now, TFA was a bit light on the details. Does anyone know how does this works, from a chemical perspective?
Web2.0: I love when people Flickr my cuil and digg my boingboing until my google is reddit and I start to yahoo
Chicago is putting in water purifying concrete.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
I did some research for school over in Hong Kong for a few months and worked with the Hong Kong Polytechnic University Civil Engineering Dep. They used titanium dioxide coatings on bricks and highway noise barriers - actually in use in Hong Kong. They also have attached titanium dioxide nanoparticles to textiles to make filtering clothing:
http://www.polyu.edu.hk/cpa/polyu/hotnews/details_et.php?year=all&news_id=255
http://www1.polyu.edu.hk/hotnews/details_e.php?year=all&news_id=964
It's great to see it catching on...
Anything is harmful in the wrong place and in the wrong concentrations. Nitrates are, for example harmful to fish in high concentrations.
Most systems have processes that are limited by the supply of some resource. Ocean ecosystems are nitrogen limited, whereas fresh water systems tend to be phosphorous limited. Thus if the nitrates are washed off into fresh water, they'll cause relatively little immediate damage unless the concentrations are high enough to be toxic. However, if that nitrate is carried downstream to the ocean, the plume of nitrogen rich water entering the ocean can cause blooms of organisms that use up so much oxygen that fin fish suffocate. This happens where the Mississippi enters the gulf.
So, how and where something like this is used makes a difference. If you imagine all the US cities along the Mississippi and its tributaries using it, and if there is a mechanism by which the nitrates make it into the rivers, then this could make the situation in the Gulf much worse. If you use it in a coastal city and only the runoff from that city affects the local ocean, the amount of nitrogen entering the ocean might or might not have any measurable effect.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
1. Pave road with this stuff.
2. Drive diesel cars on roads.
3. Nitrates -> algae blooms in marshes just off road sids.
4. Harvest algae and press to make bio-diesel.
5. Profit.
Assuming the catalyst isn't poisoned by reaction byproducts, or removed by weathering, or sealed under oil etc., or otherwise rendered inactive by environmental effects.