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APO
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Sorry I meant the apparatus was classified, I didn't want people to ask about that. Sorry for the miscommunication. The method uses Li-7 hydroxide
monohydrate, Li-6 will be better for helium yield but worse D2O yield and vice versa. The resulting neutrons from the reaction, usually hit the
protium and turn it into deuterium. So it's a bit more like D2O synthesis, than enrichment. I was just mentioning that particular reaction, I'm
looking for more info on the enrichment of D2O.
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IrC
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That is something all can discuss. Yet I fear you are still going to hit the wall of the incredible amount of water in need of processing not to
mention the insane electric bills. Info on enrichment along these lines is plentiful, info on new high yield ways is not. Nor on methods of synthesis.
I buy D2O to use with Li metal to create both the Deuterides as well as Deuterium gas for Fusor experiments. I have to say considering the expense of
concentrating your own best to bite the bullet and just buy it. U.N. is an expensive way to go however. As far as I know the cheapest place on earth
to obtain it is in Canada, although China may now be out doing them in production. Start investigating industrial suppliers, preferably ones that sell
research quantities. Believe me I wish I knew of a cheap route to owning large quantities of a very interesting chemical for amateur science. Almost
as fun for me as my Iridium Carbide.
"Science is the belief in the ignorance of the experts" Richard Feynman
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APO
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What if I use solar power?
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APO
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Also sorry IrC ,I just metioned a new method I was working for making D2O because that is similiar to enriching it. I'm also just registered on this
forum a couple days ago. Please tell me how to talk, I don't mean to piss people off.
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IrC
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You are not really pissing anyone off, I'm sure it was more me being too zealous than you doing anything incorrect. What you were describing sounded
so much like yet another amazing but never to be seen in the real world invention. I cannot tell anyone how to talk here I'm just another member like
anyone else. From being interested in many of the outside of conventional areas and watching how they operated I imagine one develops an attitude. Or
at least I did. Virtually all of them claim so much yet never allow you to see the wizard behind the curtain. Gets so irritating after a while.
To give an example, I studied the Testatika Machine for a while hoping there may be some new discovery involved. This colony claims it provides the
power for their retreat or whatever it is they call it. Then I started hearing their claim that the world was not ready for free energy so they must
keep it secret. Right there is all the proof of a sham required. If one assumes fossil fuels are killing the earth, would they then refuse to divulge
or at least market wholesale a thing which could save the planet, including their own future generations. Think about it. Because man is not ready for
their so called new technology they would condemn themselves along with everyone else to a hot polluted slow demise. In other words this is code for
the fact that they are completely full of crap and pay for their gas and electricity just like everyone else. This illustrates what I mean by lack of
logic in this area.
I can imagine two guys out cutting wood, one who invented a new artery patch. "Hey my chainsaw broke and I'm bleeding out my neck!" "Go get that new
patch you just invented it can save you!" "No I'm afraid the world will learn how it works see you on the other side" "Don't you mean in the next
dimension?"
Or something like that. No one tells you how to talk here or anywhere, no one is the boss of you. Unless your married of course, but I digress.
Solar? A really big setup if you plan to make much, again think of the many gallons of water you would have to go through. Each quantity is only going
to yield so much, requiring a new quantity of water over and over. Unless you know how to build this device you described yourself. In which case make
two, how much for the other?
[Edited on 12-31-2012 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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watson.fawkes
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Quote: Originally posted by APO  | | The method I am interested in is electrolysis, H2O splits at 1.48v and D2O splits slightly higher, if I use exactly 1.48v the H2O will hopefully split
leaving the D2O in soulution,then I would add more water to the slightly enriched soulution, and repeat the process. Any more ideas?
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Yeah. Learn some statistical mechanics. Dissociation voltages are averages, not exact figures for each
molecule. Exact voltages depend upon the specific thermal excitation of the molecule, and there's a distribution of these thermal energies. The effect
of this is to broaden what's otherwise a cliff. The result for isotope separation is that for every voltage and temperature there a ratio of isotopes
that will split. Per-pass separation isn't what you think it is.
And it's a complete newbie mistake to assume that you're going to find much D2O in nature. Almost all of it is DHO.
Chemical exchange is more energy efficient, and it's still very energy-intensive. The best known is the GS process, which uses D-H exchange between H2S and H2O. Note that the cited page mentions a 340:1 input water to output
water ratio for one such plant. There's also an ammonia exchange process, but I don't know much about it.
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ScienceSquirrel
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Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
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The Girdler sulfide process is probably the cheapest and most efficient way but you are going to need some serious engineering plus a lot of power and
water.
Really your ideal set up could be small water mill driving a turbine for power and the stream providing the water in the middle of nowhere so no need
to worry about upsetting the neighbours if your hydrgen sulfide leaks.
Even a tiny Girdler plant will need tonnes of water and hundreds of kW hours to produce a useful yield so if you have to take them from a metered
public supply your utility bill will be huge and it will excite interest from all sorts of parties
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APO
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Hmm... Norsk Hydro made it sound easy. I'm a pretty good engineer though. Maybe I could use a solar setup, and a rain collector, so that I could leave
it for several months to get a slight yield. Anyone know the exact voltage that water splits at?
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Metacelsus
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1.48 is the theoretical minimum. However, your electrode overvoltage will cause the practical voltage to be higher.
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phlogiston
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It's good to see we are back to a real discussion on the experimental details of some mad scientist experiment, in this case deuterium enrichment.
Behind that simple question 'what is the exact voltage' lies a world of complexity you appear to have no notion of.
It is dependend on pressure, temperature, electrode material, etc. Actual cell voltage drop will also include, for instance, the drop across the ohmic
resistance of the cell and the reactions taking place at the cathode.
Your questions suggest that your train of thought is that if you could hit the exact voltage where H2O splits and D2O doesn't yet, you'll end up with
a much enriched residue of D2O / DHO.
Dissapointingly, it won't work to the extent that you may be hoping for. A very small fraction of enrichment in each step of electrolysis is
realistic. Perhaps you can sell the vast quantities of hydrogen and oxygen to recover some of the cost, or use a fuel cell to recover the increasingly
enriched fractions as D2O for input to subequent steps while cutting down on electricity costs.
Deuterium enrichment has been studied extensively and it is unlikely (but never impossible) that you will find a better way than the established
methods. In a small lab setting, I think you should go for whatever process yields the best enrichment per step, regardless of energy/materials costs,
which, as has been mentioned, seems to be the Girdler sulfide process (at least, of the methods published so far).
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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kristofvagyok
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Long ago I also thought about deuterium purification and I ended up that there is no such cost effective way than buying it, but there is always
someone who want to make it free, so here are my ideas:
As we know heavy isotopes form stronger covalent bonds than their lighter counterparts; for example, a carbon-deuterium bond is stronger than a
carbon-hydrogen bond, this is why CDCl3 forms from CHCl3 in D2O.
Some D2O, cheers 
So the only effective separation could work with a method what uses something else also than water. The Gilder process works, the deuterium forms a
stronger bond with the sulfur so it could be enriched.
A version could be that acidic water is boiled with an organic substance in it what will get fully deuterated with time... E.G.: deuterobenzene-d6 is
made simply by adding benzene to D2O and D2SO4, simply boil it a bit and distill down the pure benzene-d6. Sound easy? Yes!
The problem: a lot energy is needed to boil that amount of water and getting out the deuterium from an organic compound is also not a really easy
thing .
Another idea could be (this was my long ago thought idea) that as we know hydrogen and deuterium (and tritium) is a special thing, it could be passed
into palladium forming an unstable interstitial hydride. The only problem is if we use a palladium "window" for the separation of hydrogen, it will
work perfectly, but it will also let through deuterium (not as well as hydrogen, but it will let it pass also). If someone is really good in material
science than it would worth to look up an alloy what readily adsorbs hydrogen, but not as good the deuterium.
And a third idea is also here: as we know UH3 is a really special hydride, because it adsorbs hydrogen at low temperatures, but is releases it at
elevated temperatures. I just looked up that what is known about UD3: almost nothing. It is mentioned (according to reaxys) in 3 article and they did
not checked that what temperature it gives off the deuterium (or just I didn't find it).
The idea would be that that pass hydrogen/deuterium in a heated steel tube what contains uranium granulates at that temperature where the UH3 fully
decomposes, but the UD3 not yet.
[Edited on 2-1-2013 by kristofvagyok]
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IrC
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Just a thought but edge effects on the electrodes could be reduced by using spheres or partial spheres not completely immersed. This I think would
allow for a more controlled potential if combined with the proper regulation scheme in the associated power source. If there is a critical yet narrow
window for the proper voltage it seems this might be a useful approach. Of course they must be extremely smooth.
"Science is the belief in the ignorance of the experts" Richard Feynman
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watson.fawkes
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| Quote: Originally posted by IrC | | Just a thought but edge effects on the electrodes could be reduced by using spheres or partial spheres not completely immersed. This I think would
allow for a more controlled potential if combined with the proper regulation scheme in the associated power source. |
This is in the right spirit of how to get consistency, but I don't think it's the right geometry. Any good analysis of this issue
needs an account of the electric field within the electrolyte. Edge effects in electrodes come from fringing fields, and eliminating them is
what's wanted. The most important aspect of this is to minimize the gap between electrodes. This leads to looking at parallel plates. I would consider
putting a plate electrode within a non-conducting frame, so that the edge of the conductor was not at the edge of the plate. This would eliminate most
of the field component in directions along the plane of the plate. In addition, with a small gap, you'd likely need active pumping of the electrolyte,
no small complication if you have high pH electrolyte (typically using KOH) to increase conductivity.
The other thing necessary to get this kind of thing right is to use a potentiostat with a sense electrode. This kind of supply changes the voltage
drop across the main, high-current electrodes in order to keep the voltage between one main electrode and the sense electrode constant. The current
required to sense voltage can be minuscule, down in the nA range, in order to minimize resistance error in the sense electrode, required if you need
to accurate sense in single mV so that you can regulate to 10 mV.
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AJKOER
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Here is a general idea that you may find useful.
1. Separate out (via electrolysis) the oxygen. Left with H2 and D2.
2. Combine with compound X, so you now have, say, HX and DX.
3. Select element/compound X so as to maximize a difference in a physical property that can be used in separating HX from DX. For example, you started
this thread focusing on the voltage at which the H2O and D2O split occurs.
The logic here is that the element Oxygen may not be the best choice.
The fact may be it doesn't materially matter what the element X is, or you do not have the necessary data to know.
[Edited on 2-1-2013 by AJKOER]
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kristofvagyok
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Just and idea, but HF has a boiling point: 19.4 °C and DF has a boiling point 18.66 °C.
Who is enough brave to try it out?
I have a blog where I post my pictures from my work: http://labphoto.tumblr.com/
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