Sciencemadness Discussion Board

Increasing oxidation rate by bubbling air into water - pressurize system?

RogueRose - 28-10-2016 at 14:53

I read that water isn't capable of retaining all of the O2 that is bubbled through it (say in a 5 gal bucket with 1cfm air per minute). Percentages were hard to pinpoint but some said .5% dissolved O2 was max in water so when pumping 21% O2 through, much is wasted in the scenario above.

I'd like to figure out a way, if possible, to increase the amount of dissolve O2 in the water and I suspect that putting all of this under pressure may be a solution to getting more dissolved. I was thinking of pressures of 45-90 PSI as these pressures can be handled by a standard air compressor.

My theory is that if the amount of O2 being absorbed is linear then 45psi should =~2% and 90psi about 3.5% (each ATM = .5% and STP = .5%).

If the above correct then even though the volume being injected is less, the amount of O2 should be the same, but the amount absorbed is much greater.

The point of this is to be able to replace H2O2 for some reactions where oxidation is needed and can be done in water (or possibly other liquids that will dissolve O2).

I'm also looking into what role temperature plays in this and if that can be used to increase amount of dissolved O2.. --NOTE edited/added - I found a paper on O2 vs temp and it looks to be a pretty linear correlation as the temp rises, O2 levels drop. From 0-45C there is about a 60% decrease in the dissolved O2 per L which is already a pretty small amount. This is why I think pressure could be such a good option for increasing dissolved O2.

Does anyone have any knowledge about this topic that can help solve this issue?

Dissolved O2 and CO2 Paper





dissolvedair2.jpg - 88kB

[Edited on 28-10-2016 by RogueRose]

[Edited on 28-10-2016 by RogueRose]

Meltonium - 29-10-2016 at 04:15

For many gasses, if you increase the pressure and drop the temperature, they stay in solution better. You are likely to have more O2 dissolved in a warm, pressurized container than if you had an unpressurized colder solvent.

[Edited on 29-10-2016 by Meltonium]

zed - 31-10-2016 at 15:43

Ummm. As I recall, regarding gases; Henry's law states: Double the pressure...and you double the solubility.

Unaware of the exact parameters, but the trout tell us that there is more dissolved oxygen in cold water. The colder the better. Trout don't make it in warm water.