White Yeti
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Oxygen generating reactions
We've all heard of oxygen scavengers, many of them sulphur compounds. They are used as corrosion inhibitors for pipelines and cisterns.
I was wondering if the opposite of an oxygen scavenger exists, a kind of "water oxygenator" that slowly releases oxygen gas when dissolved in water.
I've searched all over the place and found nothing except hydrogen peroxide and peroxide compounds. Either I have not done enough research, or such a
compound does not exist.
You might be wondering why on Earth I would want to oxygenate water with chemicals, so here's the reason why:
I've built aluminium air batteries that use oxygen as an oxidant via the following half reaction:
2H2O + O2 + 4e- ----> 4OH- +.40V
The problem is that oxygen diffuses very slowly into water, even if it's kept ice cold. The only oxygen that participates in the reaction is the
dissolved oxygen, not the oxygen in the air. A typical cell thus produces a fair amount of current when the water has just been taken from a tap, but
the current drops sharply after all the oxygen has been used up. I would like to improve performance by constantly replenishing the dissolved oxygen
in the electrolyte.
Setting aside the classic oxygen generating reactions such as NaClO + H2O2, KClO3 +catalyst, H2O2 +MnO2 and the like, I'd be interested to know about
other oxygen releasing compounds and reactions.
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LHcheM
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How about barium ferrate in acid solution? Or chromium peroxide (CrO5)??
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Endimion17
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Try playing with different forms of your setup, and see if any plants can be incorporated. By plants I mean any photosynthetic organism.
I'm not saying you should dunk some wildgrass into the electrolyte  , just play
with the setup.
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White Yeti
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Quote: Originally posted by Endimion17  | Try playing with different forms of your setup, and see if any plants can be incorporated. By plants I mean any photosynthetic organism.
I'm not saying you should dunk some wildgrass into the electrolyte , just play
with the setup. |
I actually thought about doing that, but the problem is that the reaction would be dependent on sunlight. Don't forget that plants will use oxygen
when no sunlight is available. When the plant decomposes, you're in a heap of trouble because bacteria would drain all the oxygen out of the water.
Good idea though.
I've played with the setup, but it just gets nowhere. I've tried a flat design with a high surface area, I've tried permeable membranes and hydrogen
peroxide, but nothing seems to be doing the trick. Hydrogen peroxide just make a foamy mess. This is basically my last resort before dissolving oxygen
manually via balloons :\
"Ja, Kalzium, das ist alles!" -Otto Loewi
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Endimion17
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That's why you shouldn't connect the electrolyte and the water in which the plant lives. 
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DJF90
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Have you tried sodium percarbonate or sodium perborate? They're hydrogen peroxide "adducts" (for lack of a better word) typically used as cleaning
agents in laundry. Also, UHP (urea-hydrogen peroxide clathrate) may find application in your cell.
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symboom
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bleach and hydrogen peroxide is one of the cheapest
and heating sodium chlorate to decomposition
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