DIY Oxygen Absorbers
 

DIY Oxygen Absorbers

Most commercial oxygen absorbers are nothing more than fine iron powder mixed with a polymer grain to allow air circulation thru the powder - the rusting of the iron powder does the oxygen scavenging of the containers contents. Its that simple. Its also very easy to replicate that process.


Materials;

*Steel Wool '0000' superfine (don't use "SOS" pads)

*Salt (table salt is fine)

*Paper towels

*Stapler (a cheap "TOT" kids stapler works too)


Pending on the container size take a wad of steel wool and lay it on a open paper towel, sprinkle table salt over the steel wool and work it into the fibers, fold the towel over and staple in an envelope shape. That's it !

The salt's acidity activates corrosion of the fine steel wool and the rusting of the steel absorbs oxygen in the container. Just leave a wad of steel wool outside overnight to see this process in fast forward ... you don't even need the salt for that experiment.

Keep all your unused DIY Oxygen Absorbers in air-tight freezer bags until you need them.




BTW, for 5 gallon containers I use two DIY Ox Absorbers the size of a fat legal letter envelope, one at the bottom and one on top of the contents. You can use paper lunch bags too, as long as they are porous - no waxed bags.

Make sure to use mylar bags in those buckets !



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Re: DIY Oxygen Absorbers
 

Thanks, that is a good tip.

Re: DIY Oxygen Absorbers
 

I'm not a chemist. So I don't know the answers to my questions. Perhaps you do.

First of all, I never heard anyone refer to salt as an acid, especially in the context of dry salt.

In the absence of water or any humidity, would this O2 absorber work? I know that if I leave steel wool outside overnight that it will rust -- condensation and all that.

But, in the presence of dehydrated food and the remaining air in your storage container, is there enough moisture to enable removal of all the oxygen in your preps?

Just asking. All you chemists out there, speak up :)

Re: DIY Oxygen Absorbers
 

The question is will it pull a tight vaccuum using mylar? If it does it should work fine in a pinch. I doubt I would ever do it that way unless O2 absorbers were no longer available, but still nice to know assuming it actually works.

Re: DIY Oxygen Absorbers
 

Salt absorbs moisture and increases conductivity of the ion exchange of iron/steel and water (moisture).

In the absence of water the standard reduced iron powder oxygen absorbers won't work either. That's why you need to keep them in a sealed container prior to use, the powder combines with the moisture in the air and starts the chemical reaction - RUST.

Corrosion occurs in the presence of moisture. For example when iron is exposed to moist air, it reacts with oxygen to form rust,

------------------------------------------------------------

Fe2O3 - X H2O

The amount of water complexed with the iron (III) oxide (ferric oxide) varies as indicated by the letter "X". The amount of water present also determines the color of rust, which may vary from black to yellow to orange brown. The formation of rust is a very complex process which is thought to begin with the oxidation of iron to ferrous (iron "+2") ions.

Fe -------> Fe+2 + 2 e-

Both water and oxygen are required for the next sequence of reactions. The iron (+2) ions are further oxidized to form ferric ions (iron "+3") ions.

Fe+2 ------------> Fe+3 + 1 e-

The electrons provided from both oxidation steps are used to reduce oxygen as shown.

O2 (g) + 2 H2O + 4e- ------> 4 OH-


- Wiki

Re: DIY Oxygen Absorbers
 

Well, when you put it like that anyone can understand it. :confused_ma::biggrin:

Re: DIY Oxygen Absorbers
 

Well, I understood it. I took high school chemistry, after all (45 years ago.) :36_1_34:

My only question is: if you're storing dehydrated foods, which have little to no moisture, is there enough humidity in the air inside the jar to absorb the oxygen contained in that air? But that question applies equally to commercial O2 absorbers.

Re: DIY Oxygen Absorbers
 

You want it powdered or in small chunks if possible as this massively increases the surface area, just like the real O2 absorbers.

I'd also use plastic bags, perforate those first then put the tissue envelope in. Just in case the tissue deteroriates over time and you end up with steel wool or particles all through your nice food. I'd use tape to make the envelope but that's just me...

Re: DIY Oxygen Absorbers
 

Not a chemist, but I'm pretty sure from memory that in chemistry basic salts were just referred to as salts. Dissolving a salt in water would create an ionic solution.

Table salt (ignore the iodine content):

NaCL = Na+ Cl- ions in solution.

Not exactly an acid, but something that can react with other elements or chemicals placed in solution. A corrosive effect does not necessarily make something an acid as far as I'm aware. Very basic solutions (alkaline) ones can cause massive damage and they are effectively the opposite to an acid.

Re: DIY Oxygen Absorbers
 

I think he means that salt increases conductivity of water and that increases ion exchange of the steel wool and moisture.

I'm sure it works on that same principals as the commercial units.






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Re: DIY Oxygen Absorbers
 

Concerning operation on dehydrated foods: Maybe a small drop of water placed on the absorber prior to packing with the food is prudent in order to start the chemical reaction? I would think that unless you are working super duper quick that the reaction will have begun from exposure to the moisture in the same air you're breathing and working in, though.

Re: DIY Oxygen Absorbers
 

Pat wrote" Keep all your unused DIY Oxygen Absorbers in air-tight freezer bags until you need them." NOOOOOOO. Normal freezer bags are just thin LDPE/HDPE (low/high density polyethylene), which just plain SUCKS as an oxygen barrier material. I guess it's better than nothing, but it's not much of a barrier. Ever notice how peanuts go rancid when stored in the normal grocery store "freezer bags"???? Even the nylon/LDPE laminate bags (Foodsaver, et al) are not anywhere near as good as mylar as oxygen barriers.

While this thread may be useful in a SHTF situation, where you happen to have plenty of degreased/oil-free steel wool pads, for now I'll stick to "real" oxygen absorbers. They're cheap enough through the ldscatalog.com where I don't feel any need to experiment with my food preps.

For now at least, there's no need to fiddle around with putting drops of water on your homemade oxygen absorbers. Use the real thing.

Re: DIY Oxygen Absorbers
 

I didn't realize this thread could go on forever ... its not that complex.

The steel wool is used for furniture restoration, like sandpaper, local hardware store variety, no grease or oil in it.

It "rusts" (oxidation) combines with oxygen.

Its not rocket science.