Making heavy water

[Gilded]

if you're trying to separate two components that have the exact same chemistry with only a slight difference in reaction rates its going to be very energy expensive to do. there isn't much of a way round this.

 

The slight difference isn't so slight with H vs. D as opposed to let's say U-238 vs. U-235. While basically every isotope enrichment process requires significant amounts of energy I'm pretty sure a gas centrifuge setup is less efficient than the Girdler setup in this case.

[Mr Skeptic]

Anybody remember years ago a high school student making heavy water for a science project? NASA had spent millions trying to figure it out and this kid did it in his mom's kitchen. Maybe about 25 years ago. Any info?

 

Another funny thing is how the US military spent many many millions trying to figure out how to make explosives, when Chinese chemists could make explosives thousands of years ago.

 

i would have went for electrolysis followed by a seperation of normal hydrogen from deuterium.

 

Me too, and then I would sell the hydrogen to make up for the cost of electrolysis. I figure the deuterium would be much easier to separate as a gas and without the heavy O atom.

 

It might be possible to create a biochemical separation process that would be extremely efficient, but not with current technology.

Edited October 22, 2008 by Mr Skeptic
multiple post merged

[John Cuthber]

A vertical column makes it easier since all three are less dense than air and will want to diffuse up.

 

Thanks for clarifying your expertise in this matter.

[insane_alien]

lol, i missed that bit. what a div.

[Gilded]

I figure the deuterium would be much easier to separate as a gas and without the heavy O atom.

 

The relatively heavy oxygen doesn't really matter that much in isotopic exchange though.

[Mr Skeptic]

The relatively heavy oxygen doesn't really matter that much in isotopic exchange though.

 

It would make the difference in weight much smaller as a percentage.

[Gilded]

It would make the difference in weight much smaller as a percentage.

 

The mass (and thus reaction rate) that matters is of deuterium vs. hydrogen. The "parent" atom (sulfur, oxygen...) doesn't seem to be as much of a concern in the process.

 

The more I read about this the more I'm convinced that initially chemical enrichment methods require actually significantly less energy than distillation or electrolysis. Of course eventually you will have to move on to (vacuum) distillation if you want a reasonably pure product.

 

Perhaps a bit weirdly, I've found no mention of gas centrifuge cascades similar to those used to enrich uranium. Distilling liquid hydrogen is possible (2.7K boiling point difference between H2 and D2), but that seems unfeasible compared to distillation of water.

[gary350]

How much heavy water do you want?

 

First you need to have a very long electical spark in the range of several million volts.

 

http://home.earthlink.net/~gary350/tc10-4.jpg

 

Next you have to direct the high voltage spark along a straight line with magnets along the path of the spark. Line up several magnets in opposite order along the path, N, S, N, S, N, S, N, S, N, S, etc. this removes all the electrons and protons from the spark leaving only the neutrons.

 

The neutrons are shot into water now you have to slow them down other wise they travel all the way through the water and out the other side. I have forgotton how to slow down neutrons but if I remember correctly I beleive you use a block or grafite or lead I can not remember.

 

After you saturate the water with neutrons you have heavy water.

 

NOW......what are you going to do with heavy water? You could build an atomic hand grenade and throw it across the back yard.

[insane_alien]

gary, you do know that sparks are entirely made of moving electrons right? there are no neutrons in a spark. me thinks you have been reading too many crackpot sites.

[gary350]

gary, you do know that sparks are entirely made of moving electrons right? there are no neutrons in a spark. me thinks you have been reading too many crackpot sites.

 

You may be right. It sure does seem logical. I remember a movie in high school science class where magnets were used along a long spark to remove the electrons and protons the neutrons continued on. Hay...........that was 44 years ago. Maybe I dreamed that one night when I was asleep. LOL.

[Imaginer1]

Really, "heavy" is an opinion. And really water DOES have a weight. Do you want to increase the weight of the water without changing space it takes? you may need to work with density. You could definitely go VERY FAR into this and get an A++ and maybe a national award if you increased the weight by making it not H2O, but H402. (and the probability is so far away from it not exploding after you make it)

[iNow]

Really, "heavy" is an opinion. And really water DOES have a weight. Do you want to increase the weight of the water without changing space it takes?

 

You act as if people here are talking about water that's eaten too many Krispy Kreme donuts, and it's clear you have no idea what heavy water is. Start here. Read. Ask questions when you don't understand.

 

http://en.wikipedia.org/wiki/Deuterium_oxide

[nitric]

the recomended way is to bubble HS through the water first then distill and thats how it was first isolated

[Flashman]

So umm, you wouldn't get anywhere by centrifuging water at 1C would you? Thermal diffusion still too great?

[Ultimate Geek]

Hello, I have found me a new useless project: making heavy water.

Q:Why? A:I dont know.

Q:What are you going to do with it? A:Posess it, or I will get the D of it.

 

Well, I have some questions about it, are there other ways than Electrolysis of Water? They told me: try distillation, but isn't it cheaper just to let water vapourise and safe the last bits of water and vapourise that again and again and again? I don't mean to heat the wather, just let it stand there till there is only 1/10 left.

 

will it work?

 

Your best bet for getting D2O is by using Electrolysis combined with weight analysis. Electrolise water and monitor its weight as you remove the gas. for every 7000 water molecules you remove you will have 1 D2O molecule. Once you see the weight reducing at 1/25 the rate of your original atrting weight loss add water and repeat. THIS WILL TAKE A LONG TIME!

[Mrl4]

heavy water and normal water have slightly different boiling point: heavy water boils at 101 degrees C, while normal water boils at 100. You should have a very precise heater. That way you can make the normal water evaporate, and get heavy water.

 

this is not fully reliable but you could always try...

Edited November 27, 2011 by Mrl4

[insane_alien]

heavy water and normal water have slightly different boiling point: heavy water boils at 101 degrees C, while normal water boils at 100. You should have a very precise heater. That way you can make the normal water evaporate, and get heavy water.

 

only if you have an awful lot of patience or are willing to build an extremely large distillation facility.

 

distillation loses effectiveness very rapidly as boiling points converge.

[mississippichem]

only if you have an awful lot of patience or are willing to build an extremely large distillation facility.

 

distillation loses effectiveness very rapidly as boiling points converge.

 

Yeah true. That might take a mile high fractional distillation column.

 

You can't get away with pressure swing distillation either because both components are essentially chemically identical.

[insane_alien]

Yeah true. That might take a mile high fractional distillation column.

 

You can't get away with pressure swing distillation either because both components are essentially chemically identical.

 

I calculated it (approximately) once. IIRC it came out at something like 30 km tall.

 

Of course that can be split to multiple smaller columns. but still.

[imatfaal]

!

Moderator Note

yojojo12 - your speculation regarding heavy water cold fusion was split off and moved to the speculations forum. Please try and keep on topic and ensure non-mainstream ideas/amswers are kept in speculations

[Suxamethonium]

Has anyone here ever tried a small scale system based on the Girdler Sulfide Process?

 

I figured that cascading would be resource consuming- but could always set it up in 'batches' and run through the set up repeatedly. Would also need to recover H2S which could prove irritating.

[Ducan]

Great, long-running topic!

 

I'm intrigued with heavy water too because of this post:

 

http://groups.google.com/group/can.general/msg/bcbbf27e09c8cc2e?pli=1

 

It's a story (anonymous, for reasons which will be obvious) about a man who claims to have made his own heavy water reactor. Gosh! If he can to it, why can't we have one in every county? And stop worrying about heating and AC bills, for starters! Everyman a part-time nuclear power plant operator.

 

Another video (this one more credible -- an MIT free-course lecture) says that the biggest expense in heavy water reactors is the cost of the heavy water -- $1billion plus. (????)

(Heavy water is discussed around minute 10, but the whole lecture is fascinating).

Question for the group: can you use the lower Freezing temperature of D2O to extract it from regular water? Freeze half the container, draw off the (presumably) higher D2O water, repeat.

 

For extra credit, how about centrifuging the water while freezing?

 

[JJR]

Question for the group: can you use the lower Freezing temperature of D2O to extract it from regular water? Freeze half the container, draw off the (presumably) higher D2O water, repeat.

 

 

The freezing point of D2O is actually 3.82 degrees C (38.876 degrees F), significantly higher than that of H2O. It is also about 10% denser. EDIT: Unfortunately it's also soluble in normal water, which means no amount of freezing or remelting is going to separate them.

Edited June 5, 2014 by JJR

[John Cuthber]

Sorry, but that won't work.

Heavy ice is soluble in ordinary water. This bit "a frozen sample of D2O will sink in normal water, and remain frozen so long as the water temperature is kept below ~38.9 degrees F." is wrong.

 

It's a bit like saying if I cool a mixture of salt and water below the melting point of salt (about 800 degrees C) the sale will freeze out.

Well, look at the oceans- that's not what happens.

In fact it's even worse.

When you cool salty water at least some of the salt might come out of solution as fairly clean salt.

 

If you cool a mixture of normal water and heavy water you get a mixed ice.

The ice is slightly richer in D2O than the original water, but it's nothing like pure.

[JJR]

Heavy ice is soluble in ordinary water. This bit "a frozen sample of D2O will sink in normal water, and remain frozen so long as the water temperature is kept below ~38.9 degrees F." is wrong.

 

Thank you for the correction. I clearly misunderstood the descriptions that I read and didn't realize it was soluble. Will edit my post.