Separating Hydrogen gas into protium and deuterium hydrogen molecules

[3bromopyr]

Given a volume of hydrogen gas (mixture of protium and deuterium hydrogen), how one might separate this into

only protium hydrogen?

Knudsen diffusion? (MW1/MW2)^^0.5

MW deuterium (H2) = 4.028

MW protium (H2)     = 2.0158

(4.028/2.0158) ^^0.5 = 2^^0.5 = 1.414

Separation factor of 1.41 is possible by diffusing through a membrane.

[Sensei]

If aim is to have Deuterium, search net how to make heavy water. Once you have heavy water you can just do electrolysis of water.

Typical source of Hydrogen in lab is electrolysis of water. Normal tap water has very little amount of Deuterium. Sea water has a bit more. Search net for "abundance of Deuterium". It is 1 per 6400. So there are three possible combinations H₂, DH and D₂. H₂ is the most abundant and D₂ is the least abundant. Similar situation is with water. There are three combinations H₂O, HDO and D₂O.

From normal water you make semiheavy water and then semiheavy water is enriched to heavy water.

https://en.m.wikipedia.org/wiki/Semiheavy_water

From more info read production of the heavy-water 

https://en.m.wikipedia.org/wiki/Heavy_water

 

Edited March 6, 2021 by Sensei

[3bromopyr]

Thank you Sensei for replying.

I am interested in removing the small amount of deuterium that is in tap water.

Yes, I could start with regular water (or deuterium depleted water) and then apply electrolysis. I would then have hydrogen gas (using DDW would give deuterium depleted hydrogen gas.) Could I not then separate the hydrogen gas produced further to reduce the deuterium content? The hydrogen gas produced would be a mixture of H₂, DH and D₂ (where H represents protium). Deuterium has different properties than protium. Would there be a way to separate the hydrogen molecules containing deuterium and those only containing protium? For example, by diffusion through a membrane?  

[John Cuthber]

You can buy deuterium depleted water.
 

On 3/6/2021 at 5:27 PM, 3bromopyr said:

Separation factor of 1.41 is possible by diffusing through a membrane.

Which means you start off with 0.0115% deuterium and get 0.00815 %  (or 0.01311% if you are trying to concentrate it.)

You need a lot of stages to get a good product.