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Old 02-12-2011, 04:03 AM
cody cody is offline
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Join Date: Jun 2008
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Quote:
What is a good practical method of removing CO2 from distilled water that will not effect the functioning of the cell ?
mikrovolt,

I had brought this up in the other thread. This is what i initially believed was running these cells, water and CO2 forming carbonic acid H2CO3 and thereby creating a galvanic reaction between the dissimilar metals. The temperature findings John B has brought to light make me question my initial theory that it was galvanic. But regardless of what it is, if you are using water, you will be dealing with CO2 and corroding metal from the carbonic acid. This is what i found when researching this: Water absorbs CO2 from the air through a process called diffusion. Basically the air will have a higher concentration of CO2 than pure distilled water, so the CO2 diffuses to the area of less concentration in the water. If your cell is open to the air, i dont see how you could avoid this from happening. So basically you would need to remove the CO2 and then seal the cell off from the air to keep it out. Removing CO2, or other gasses for that matter, is called degassing. There are a number of commercial degassing systems available. But the easiest and cheapest way i can think of is what we did in chem class, boil it. That should get a good amount of it out, maybe not as good as other methods though.

Oddly enough, as fresh water tends to be slightly acidic from CO2, sea water however is slightly basic. But then of course your dealing with the salt corroding your metals.

Maybe there are chemicals that would help, maybe Johns alum is doing this, i dont know. I would just degas the water and then just seal the water off from the air somehow while trying not to effect the function of the cell. Or of course find materials that dont corrode.



Cody
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Last edited by cody; 02-12-2011 at 04:15 AM.
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