Recently WUWT carried a story about “solar roads” which had a ridiculous premise with a big batch of “feel good” Eco-egineering that is technically and economically implausible. This idea for catalytic reduction of smog looks far more plausible and less expensive.
Students develop titanium dioxide roof tile coating that removes up to 97 percent of smog-causing nitrogen oxides
RIVERSIDE, Calif. (www.ucr.edu) — A team of University of California, Riverside’s Bourns College of Engineering students created a roof tile coating that when applied to an average-sized residential roof breaks down the same amount of smog-causing nitrogen oxides per year [produced by] as a car driven 11,000 miles.
They calculated 21 tons of nitrogen oxides would be eliminated daily if tiles on one million roofs were coated with their titanium dioxide mixture. They also calculated it would cost only about $5 for enough titanium dioxide to coat an average-sized residential roof.
That would have a significant impact in Southern California, where 500 tons of nitrogen oxides are emitted daily in the South Coast Air Quality Management District coverage area, which includes all of Orange County and the urban portions of Los Angeles, Riverside and San Bernardino counties.
Last month, the research by the UC Riverside team – Carlos Espinoza, Louis Lancaster, Chun-Yu “Jimmy” Liang, Kelly McCoy, Jessica Moncayo and Edwin Rodriguez – received an honorable mention award for phase two of an Environmental Protection Agency student design competition.
A UC Riverside student team who worked on the project last year received $15,000 as a phase one winner of EPA’s P3 (People, Prosperity and the Planet) competition. That team consisted of William Lichtenberg, Duc Nguyen, Calvin Cao, Vincent Chen and Espinoza (an undergraduate then who is now a graduate student at UC Riverside).
Both teams were advised by David Cocker, a professor of chemical and environmental engineering, and Kawai Tam, a lecturer at the Bourns College of Engineering.
Nitrogen oxides are formed when certain fuels are burned at high temperatures. Nitrogen oxides then react with volatile organic compounds in the presence of sunlight to create smog.
Currently, there are other roofing tiles on the market that help reduce pollution from nitrogen oxides. However, there is little data about claims that they reduce smog.
The students set out to change that. They coated two identical off-the-shelf clay tiles with different amounts of titanium dioxide, a common compound found in everything from paint to food to cosmetics. The tiles were then placed inside a miniature atmospheric chamber that the students built out of wood, Teflon and PVC piping.
The chamber was connected to a source of nitrogen oxides and a device that reads concentrations of nitrogen oxides. They used ultraviolet light to simulate sunlight, which activates the titanium dioxide and allows it to break down the nitrogen oxides.
They found the titanium dioxide coated tiles removed between 88 percent and 97 percent of the nitrogen oxides. They also found there wasn’t much of a difference in nitrogen oxide removal when different amounts of the coating were applied, despite one having about 12 times as much titanium dioxide coating. There wasn’t much of a difference because surface area, not the amount of coating, is the important factor.
The current team of students, all of whom are set to graduate in June, are hopeful a new team of students will continue with this project and test other variables.
For example, they want to see what happens when they add their titanium dioxide to exterior paint. They are also considering looking at applying the coating to concrete, walls or dividers along freeways. Other questions include how long the coating will last when applied and what impact changing the color of coating, which is currently white, would have.
The titanium dioxide coated tiles break down nitrogen oxides using catalytic reduction. But what does it break down the nitrogen oxides into, oxygen and nitrogen gasses? And how long do the tiles continue to work before they must be repainted?
Louis says:
June 4, 2014 at 11:50 pm
….But what does it break down the nitrogen oxides into, oxygen and nitrogen gasses? And how long do the tiles continue to work before they must be repainted?
Read a but slower. The last part of your query is answered at the end of the article:
Why is someone wearing slippers in the lab? Tops of feet exposed around chemicals and heavy objects? OSHA would not approve.
@KD – Exchange student from Rio de Janeiro ?
For example, they want to see what happens when they add their titanium dioxide to exterior paint. They are also considering looking at applying the coating to concrete, walls or dividers along freeways. Other questions include how long the coating will last when applied and what impact changing the color of coating, which is currently white, would have.
http://www2.dupont.com/Titanium_Technologies/en_US/uses_apps/coatings/
http://pubs.acs.org/doi/pdf/10.1021/ie50362a017
Chalking of Titanium Dioxide Pigmentated Exterior Finishes
R. E. Troutman , W. G. Vannoy
Ind. Eng. Chem., 1940, 32 (2), pp 232–237
DOI: 10.1021/ie50362a017
Publication Date: February 1940
Note: In lieu of an abstract, this is the article’s first page.
Oh look, I can buy 48 hours of access to this 74-year old article for only $35!
I think these intrepid researchers can find previous work to help them out.
Paints already contain TiO2.
Titanium is quite a dangerous metal. If there are any atoms not oxydised it can explode into flames as it used to do for me when cleaning an electron evaporation machine for which I was responsible. Once oxydised, as in paint, you would probably need to paint the planet white as recommended by oblarny’s idiots.
If TiO2 is such a good eliminator of Nitrogen oxides, shouldn’t it be used at source (eg, in auto catalytic converters) – or can’t it be formulated to handle the necessary temperatures? It is, I am told, slightly cheaper than platinum…
white painted roof tiles, think of the increase in albedo.
Important Question:
Where Are The Control Samples?
If how much is used doesn’t matter, then did they try it with none at all?
You would test untreated tiles, straight from the box.
If there was surface prep before applying the titanium dioxide, then you test prepped but bare tiles.
I doubt they simply dusted the tiles and got the precise quantity and quality of coating they wanted. So the substance was in a binder to make it stick to the tiles. Then you test tiles with the just the binder applied, onto tiles that are or are not prepped as indicated.
If a medical researcher said it didn’t matter how much of the active ingredient was ingested, the same beneficial effect was observed, I’d seriously wonder if the active ingredient did anything at all.
They say this is a catalyst effect, so only the amount of surface area matters.
But titanium dioxide is an additive in almost practically all colorized paints and coatings, and colored plastics, etc.
If this effect is real, then won’t any exterior wall using titanium dioxide-containing paint, when exposed to sunlight, also be breaking down smog-causing nitrogen oxides?
If the effect is real, why would any modern city have smog problems at all?
I want to see their work. I want to see what were the controls.
johnmarshall
Paints already contain TiO2.
Very true – glossy white paint contains a high percentage of Titanium Oxide. Titanium Oxide was famously the first ever brilliant white paint pigment – until its discovery, artists were forced to use slightly off white pigments such as zinc white.
http://www.webexhibits.org/pigments/indiv/history/tiwhite.html
In addition, most roofs are rapidly covered in a thin deposit of dust or even moss – it only takes a thin layer to prevent the air from reaching the roof tile. This also applies to paint on house walls – which is probably why painting walls white has no noticeable impact on pollution.
The tiO2 in paint is non-catalytic rutile; the tiles are coated in anatase, which is catalytic.
This idea is at least 25 years old.
What is this fixation with 97% about??
http://www.construction-chanvre.asso.fr/performances_fr_20_31.html
“chanvre” is hemp – I’m not sure it is the proper word –
recently I saw an old building (middle age – with wooden pieces) restored with what they call “hemp concrete bricks” – and also it is used for inside walls –
try it – you can grow this plant – it is important – cheap and simple
EPA’s P3 Program: People, Prosperity and the Planet, they sell you any crap. Just ignore their BS.
Is interesting to compare the way the scientific community reacts
to non-climate related discoveries;
” the announcements should be made after submission to journals and vetting by expert referees. If there must be a press conference, hopefully the scientific community and the media will demand that it is accompanied by a complete set of documents, including details of the systematic analysis and sufficient data to enable objective verification.”
http://www.nature.com/news/big-bang-blunder-bursts-the-multiverse-bubble-1.15346
http://www.habitatnaturel.fr/Magazine/Voir-tous-les-produits.html
this is a magazine in natural materials for houses
(…) The tiles were then placed inside a miniature atmospheric chamber that the students built out of wood, Teflon and PVC piping.
The chamber was connected to a source of nitrogen oxides and a device that reads concentrations of nitrogen oxides. They used ultraviolet light to simulate sunlight, which activates the titanium dioxide and allows it to break down the nitrogen oxides.
…
Seriously, if you’re going to study a substance, then study just the substance.
Grab large test tube and a two hole stopper. Use long glass tube that almost reaches the bottom, coat outside with the substance. That’s the inlet. Other hole gets a short tube, that’s the outlet.
Purge the tube with nitrogen, then pump in the nitrogen oxides and any other atmospheric gases you think are important. Illuminate tube with ultraviolet light, measure intensity to check replication of test conditions. Test concentrations at outlet.
Simple.
The project, as done, seems more like something high school chem students could set up and perform, with help from the vo-tech students learning construction trades. And this is college work, that scored some EPA funds?
Curious. The title says “roof tiles”, and “Garfy” is posting links to French sites featuring building materials made from hemp.
Somewhere someone’s spam bots are suffering from a severe lack of proper context and content detection.
This is funny. He’s advising the US readers as well to grow hemp, which currently isn’t legal by federal law.
Let’s see what else gets posted.
when I say “hemp” I mean a different variety (you cannot smoke it) – and also obtain linen like with flax – and spread it under the tiles
Not such a novel idea actually. It’s been around since at least 2007 when Italcementi patented a TiO2 cement that converted nitrogen oxide to soluble nitrate. When used in concrete it is called a photocatalytic or self cleaning surface.
I wonder how much energy it takes to refine a tonne of titanium?
They should have removed a few tiles from roofs and tested them, to see if dust and sunlight had degraded their cleansing ability.
Sounds interesting.
Some questions.
1. How well do these things work in stagnant air once the NOx near the surface has been eshausted? If there were much wind, there probably wouldn’t be a smog problem/
2. I realize that there are a lot of tile roofs in coastal California, but are they really a good idea in earthquake country?
3. Like Louis says, what are the reaction products? N2 and O2?
4. Is there any chance of these things catalyzing unwanted reactions as well as the desired reactions?
Garfy said on June 5, 2014 at 2:53 am:
You need background info:
It’s easier to grow marijuana, in the states that have legalized it, than it is to grow hemp, which they banned when previously banning the growing of marijuana.
Yea, but NOx is not the problem! CO2 is! /sarc.
If we get rid of all the nitrous oxide, will there be less laughter in the world?