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See the link for a description of an oxygen generator that
combines hydrogen with atmospheric oxygen, and then uses
electrolysis to separate the pure oxygen.
While the other method will work, there is a significant
regarding its overall energy efficiency. So, the goal here is to
consider some other chemical reactions. Just for fun, let's
with the element mercury.
It happens that you can heat mercury in air, and it will form an
oxide. It also happens that if you heat the oxide, it will
decompose back into mercury and oxygen. That sounds pretty
simple, doesn't it? Just do the first thing in part of the overall
device, move the resulting oxide to another part of the device,
and then obtain pure oxygen just by heating (presumably
electrically) --and return the mercury to the first part of the
Of course that particular system will have a problem in that
mercury vaporizes fairly easily, which means the person
the oxygen is likely to get poisoned by the mercury. So, what
It happens that gold oxide also decomposes with heat, and gold
not going to yield dangerous vapors like mercury. But making
gold oxide is not a simple task, alas. So, what else is there?
How about natural hemoglobin? This iron compound is such that
the lungs, oxygen latches onto it easily, and elsewhere in the
body, oxygen can be removed from it easily (both events at
temperature). I'd stop right here if I knew the stuff was stable
enough for what we might call "small scale industrial use",
shoved around in an endless loop inside a home oxygen
But what if it isn't that stable?
So, what I'd like to suggest is some molecular engineering,
starting with thinking about the hemoglobin molecule, which is
fairly complex combination of proteins that apparently
an iron atom in a way that lets it attract oxygen without
strong chemical bond with the oxygen. Our goal is to build a
different container (perhaps something as simple as a
that can do the same sort of thing, without being vulnerable to
such things as bacteria eating hemoglobin. Of course we want
to be nicely stable in terms of thermal and mechanical
manipulations, as well.
We might even do the above with some atom other than iron.
mollusc family of organisms uses a copper-based compound
oxygen transport. And who knows, perhaps if a mercury atom
appropriately surrounded, it could still work, and the weight of
the surrounding molecules would keep it from escaping the
generator, and poisoning someone.
As mentioned in the main text. [Vernon, Jan 22 2016]
Commercial Oxygen gnerators
This gets to 95% using a zeolite system. They have "portable" medical ones as well. It only takes 4 people to carry it. [scad mientist, Jan 22 2016]
When hot, combines with oxygen; when hotter, decomposes. Palladium is not volatile like mercury. Kind of expensive, though. [Vernon, Jan 27 2016]
||In my high school (or maybe Jr. high) chemistry class we
did a conservation of mass experiment where we heated
iron filings in open air to create iron oxide. We verified
that the mass had increased. Then we re-heated the iron
oxide to release the oxygen, but put a lid on it while it
cooled so very little oxygen would recombine with the
iron. After that the mass returned to the original value.
||Of course it's possible I'm remembering that wrong or
there were additional undesirable reactions occurring,
but if not, it seems to me we could just use straight iron
without having to worry about a fancy unstable
hemoglobin molecule. Of course hemoglobin would allow
this to work at lower temperatures. I think I remember
that for this experiment we had to use something hotter
than our alcohol burners.
||I guess with all that heat it would probably not be
considered energy efficient unless we had a very good
heat exchange mechanism.
||I don't understand this whatsoeveratall.
||You seem to be describing systems that can absorb
oxygen and then release it on demand, but how do
they generate oxygen?
||[MaxwellBuchanan], there exist things called "oxygen
concentrators", which were discussed in the linked/older
Idea. In both Ideas the goal is pure oxygen, not partly-
concentrated oxygen. The "releasing" method in both is
equivalent to "generation". How is that not clear?
||So this is an oxygen concentrator.
||[Vernon], interesting thoughts.
||I have no idea of the energy efficiency involved, but how about: electrolysis of water to produce H2 and pure O2.
||Run the H2 through a fuel cell that combines it with diffuse atmospheric oxygen.
||Use the power produced by the fuel cell to partially offset the power consumed by the electrolysis of water, and run the exhaust water back to the electrolysis stage.
||// How is that not clear?//
||Ah, right, so by "generation" you mean "purification".
||An oxygen generator would actually generate oxygen,
for instance by electrolysis.
||[TIB], see the linked "Old Idea".
||[MaxwellBuchanan], if heating gold oxide cause it to
decompose and release oxygen, as mentioned in the main
text, how is that not "generating" oxygen?
||//how is that not "generating" oxygen?//
||Well, yes, I guess. But I think what you're aiming at
is better described as "purifying oxygen from air". No
||Re semantics I agree with Max. You are using the device to purify oxygen out of the impure mix that is air.
||Re iron I like the idea of using plain iron. Hemoglobin works lots of jiggery pokery to side step the fact that you cant get iron that hot in an organism. But heat /cool in a machine would work fine. You could do it with induction.
||The trick here is to maximally reuse the heat, ideally keeping the iron hot enough that you can push it forward and back thru oxidize / deoxidize. If waste heat could somehow be used to drive the evacuation of the chamber to receive the oxygen that would be slick.
||//Hemoglobin works lots of jiggery pokery//
||Yes and no. At high concentrations, oxygen binds to
haemoglobin; and at low concentrations, it's
released. So it works a bit like a sponge transferring
water from a puddle to a dry paper towel.
||However, there is quite a lot of cleverness to ensure
that the dissociation curve is very steep, for efficient
||I suppose compared to something like the Krebs cycle hemoglobin is pretty straightforward.
||//compared to something like the Krebs cycle
hemoglobin is pretty straightforward.//
||There's no such thing as the Krebs cycle, not in isolation
anyhow. Especially when, for convenience, it gets
separated from the electron transport chain. Succinate
dehydrogenase is a functional component of complex II in
the electron transport chain so it all gets a bit
interconnected, and a lot of it will happily run
backwards. This morning's discovery is that humans would
probably be a bit more heart-attack proof if aconitase
wasn't so fussy about H2O2.