Hermes_Trismegistus
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Photocatalysis via titanium dioxide (nitric acid)
is a topic of no small interest to me, being that titanium is OTC from any metals supply house and the dioxide is easily prepared using concentrated
sulfuric acid.
Also, using sunlight (or moonlight) to drive a reaction does seem vaguely sorcerous.
Today in lexture, my prof (a physical chemist) was babbling on excitedly about some new research that's taken place in Japan.
It involves using concrete structures to scrub the air of NOx by submerging titanium dioxide in cheap paints. The only problem being that TiO2 is such
a powerful oxidising catalyst, they had difficult keeping it from oxidising the paint itself.
A solution was to use a Calcium Carbonate based paint(cheap like borscht).
The one major stumbling block of the whole Hydrogen fuel thing is that Hydrogen (when burned directly) burns so damn hot it oxidises Nitrogen.
If we burned hydrogen in conventional combustion engines we would make the acid rain we have now, look like distilled water.
anyway....I digress...
When TiO2 is placed in a "paint" with calcium carbonate it oxidises airborne NOx into HNO3 which reacts with the Calcium Carbonate to
produce Calcium Nitrate, CO2 and H2O.
If it works out we might end up with dazzlingly bright titanium white highways.
This instantly caught my attention, however I was puzzled as to what was donating the proton to form HNO3
Forming nitric acid on the fly using NO or finally having a use for the NO or its dimer produced during reactions would really ring my bells.
Also, I am wondering what other Photocatalysis this magic substance might accomplish.
***I couldn't decide whether or not to place this into Nitric Acid or Titanium Dioxide. So I finally settled on neither***
Arguing on the internet is like running in the special olympics; even if you win: you\'re still retarded.
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Organikum
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TiO2
is what makes utmost ALL paint nowadays so bright white.
It oxidizes nothing.
I can buy this magical compound by the kilo in every paint store - it replaces widely the former used ZnO - which can also still be bought at these
stores.
The TiO2 used in catalytical processes is a hard to impossible to prepare nanoparticolous semiconductor compound.
The best one known is produced by DEGUSSA and not really cheap.
Your prof should stop drinking/ingesting halluzinogen compounds ASAP!
The problem of the high temperatures which can result from the use of hydrogen in combustion engines is no problem at all.
- First: before lots of nitrogen would get oxidized your motor would be burned out - he dislikes such high temperatures also.
- Second: Dragster racing. Here the problem of very high temperatures in combustion engines was known long before hydrogen was involved and was
solved. How? Water. Water injection to lower the temperatures is a old hat and not very hard to do - in special if your moror burns hydrogen to water,
condense this and inject it.
Yes, progress travels slowly on a canoe... 
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Hermes_Trismegistus
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sigh
Yes, after much searching, I did find the article that got him going and some funny stories that I'll post in whimsy.
http://www.newscientist.com/news/news.jsp?id=ns99994636
also, I did know of the water injection trick. It wasn't just used on dragsters it was used jury-rigged on mig fighters by the red's. The
Yankee fighter pilots were always astounded by how the the mig's used to pull away with great alacrity in dogfights in (korea, nam) and
unofficial games of chicken on the DMZ. Especially as airforce and navy "intelligence" always said their pilots were full of shit because
blueprints smuggled out from behind the curtain always showed the technologically simple mig's as having a lower top speed. Also the migs that
soviet bloc allies flew didn't have this capability. However the proof was there, the yank's saw the mig's just start outrunning their
missiles... out of the freaking blue....
when they finally got to a reasonably complete version that had crashed (many years later) they found the reason was a thin stream of water injected
into the jet intake.
It was meant more for power than the cooling effect. The mechanism was increased compression ratio. Water is pretty much incompressible, so five
ml's of water intook into a cylinder (or jet's combustion venturi) with 95 ml's of water compresses down to 5 ml's of water and 5
ml's of fuel/air mix in a cylinder designed for 10:1 compression ratio.
So the actual compression ratio experienced by that cylinder is 20:1, a definite (but dangerous) improvement in power.
the cooling effect didn't come into play in the cylinder itself (or in the jet engine at all) because the water remained a liquid until it exited
the cylinder (because of the super high pressure in the cylinder itself) so the cooling was actually experienced by the exhaust manifold where the
pressure dropped enough for the water to turn into steam. (which again raises the pressure enough to blow off your muffler.
so if you use this system you need an exhaust system cut-out in the form of a splitter with a straight pipe.
However, the biggest problew with the system is it's unpredictability. The strangest thing noticed by the yankee pilot's is that sometime
the mig would start to pull away and then just blow up for no reason. The engineers figured that little wrinkle out pretty quick (after it was
explained to them!) the problem was that the delivery system is not very good and the liquid can clump up and drive the compression ratio so high the
engine is trying to compress pure water. Hydraulic forces tear the engine apart.
or seize it in the case of piston engines.
I wouldn't advise using water injection unless someone is chasing you intent on murder (like in war.....or a routine traffic stop in Texas)
[Edited on 7-2-2004 by Hermes_Trismegistus]
Arguing on the internet is like running in the special olympics; even if you win: you\'re still retarded.
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Magpie
lab constructor
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Mood: Chemistry: the subtle science.
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photocatalysis with TiO2 substrate
Today in the mail I received an advertisement for a home air cleaner to be installed on the suction side of one's central air fan. As it was
claiming to rid one's home air of "ethanol, ozone, paint fumes, formaldehyde, NO2, and cleaning product fumes" I became very curious as
to what was in their $1200 box so I called. They said 3 components: HEPA filtration, electrostatic precipitator, and UV light with TiO2 catalyst.
He said this technology has been used for some time in hospitals.
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Saerynide
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Not really pertaining to chem, but....
| Quote: | Originally posted by Hermes_Trismegistus
When TiO2 is placed in a "paint" with calcium carbonate it oxidises airborne NOx into HNO3 which reacts with the Calcium Carbonate to
produce Calcium Nitrate, CO2 and H2O.
If it works out we might end up with dazzlingly bright titanium white highways.
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That might solve some of the acid rain problem, but itll contribute to the green house effect even more 
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Organikum
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ehem
Water is not in a liquid state insides a combustion engine combustion chamber but supercritical. So hydraulics dont apply here anymore.
Its mainly on the internal cooling effect, believe me and my LADA....
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