Making your own ultra low oxygen CO2

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Bilsch
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Making your own ultra low oxygen CO2

Postby Bilsch » Fri Sep 09, 2016 8:03 pm

It might be possible to make one’s own, essentially oxygen free, carbon dioxide by simply placing some form of oxygen scavenger into a pressure capable container such as the ubiquitous corny keg and filling to max pressure with commercial grades of CO2. Theoretically all free oxygen should be scavenged given enough time. First thought was off the shelf oxygen packets but the idea of iron and salts possibly contaminating the gas or causing corrosion in the stainless pressure vessel are worrisome. Also the iron oxide forming reaction might not proceed to low enough percentages before coming to a halt.

So why not just use our old friend metabisulfite in solution. I would think it would not require more than a liter of water and maybe 5 grams of either Na or Kmeta, just enough to get a decent contact area. The CO2 pressure in the container should just speed up this process. The release of SO2 might be of concern however one could add an amount of sodium carbonate that would combine with the SO2 forming more sodium bisulfite and CO2 under the reaction: SO2 + Na2CO3 --> Na2SO3 + CO2. Although I’m uncertain how this would be effected by the carbonic acid formed from CO2 in solution. The exhaustion of scavenging capacity would be signaled by evolution of SO2. Certainly some SO2 in the vessel would keep stray biological organisms from making a home and one should be able to re-pressurize the container many times before exhausting its ability to get the oxygen.

The volume of gas you could process at a time would be small in comparison to what you can tap off a standard CO2 cylinder. A simple way increase the volume of course is to employ a larger keg, possibly one that has been repaired or has unsanitary welds since that would not matter for this use and be cheaper to boot.

This is all just theory at this point but I welcome any opinions on the idea.
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bensonledbetter
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Re: Making your own ultra low oxygen CO2

Postby bensonledbetter » Tue Sep 13, 2016 1:59 pm

This is an interesting concept. Here's another idea. What if you simply passed your CO2 through a diffusion stone in a keg half filled with a water and Kmeta? You could use a carbonating lid like this....

https://www.morebeer.com/products/carbo ... g-lid.html

The viability of this concept would be entirely dependent on the rate of reaction. But if it worked, all you would need to do would be install a keg between your CO2 supply and the kegs you're trying to carbonate. You really don't even need to have this special lid if you slip a hose over the tip of your liquid out and put the diffusion stone on the hose. But attaching the liquid out to a CO2 supply makes some people nervous.

Downside, you'd have to replace the water periodically.
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Bilsch
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Re: Making your own ultra low oxygen CO2

Postby Bilsch » Tue Sep 13, 2016 7:58 pm

I like your idea better to equip the keg with the carbonation cap. One could prep ~5.5 gal of water similarly to treating for mashing by boiling, cooling somewhat then adding a big dose of Xmeta. This water then transferred to the keg and tipping and overflowing it out gas in line to flush most/all of the air. You could then pressurize the keg with CO2 and force say 3/4 gallon back out of the liquid post to give a reasonable head space in your new oxygen stripping vessel. Keep the flow low and it theoretically should work with no waiting.
I'd still use some K or Na2CO3 in the solution to suppress evolution of SO2.
bjanat
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Re: Making your own ultra low oxygen CO2

Postby bjanat » Wed Sep 28, 2016 7:18 am

I have a friend who works with water degassing for offshore installations, and talked to him about making an ultrasound device with parts they have lying around. It would be interesting to have a sonotrode for homebrewing, it was mentioned in the PDF.


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