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Hi there,
We have a N2 tap in our chemical hood so that’s great! However, I am not a chemist and have no experience with degassing solutions. Could you explain for us biologist in more detail how the procedures look like. What to do and which steps. Thanks!
Ahoy,
The process is often referred to as “nitrogen stripping”, on the fly I found this useful publication on the matter.
https://www.sciencedirect.com/science/article/pii/S1388248119300980#f0005
How long and how much depend on flow, bubble size etc. As far as I am aware this is usually done for an excessively long time, so that oxygen presence is likely to be low or otherwise in the presence of an oxygen probe so that one actually knows when enough is enough.
However for your purpose I would simply let the N2 bubble through the water column for 30 minutes. I think the even more beneficial effect you would get from having nitrogen rather than air in the round bottom flask during the synthesis process.
For this I would use a three neck flask with one neck for the drip feed one neck for the N2 inflow and one neck partially but not fully blocked (idially with a valve) so that N2 accumulates but does not build up pressure within the system.
We have had a lot of scientists come back to us that did not remove oxygen, yet encountered no issues whereas others seem to encounter oxidation problems no matter what. Dissolved oxygen levels vary hugely depending on parameters surch as the water source, the surrounding pressure (altitude) and most of all temperature. Unless you have the means to really control and measure all aspects of this semi precise wet chemistry approach I would suggest empirical testing and simply trying it as best as is feasible.
The longer you bubble N2 through the system the less O2..
The hotter the liquid the less O2 ..
The less O2 is present during the vigorous stirring the less will diffuse into the liquid ..
But when is it enough? Unfortunately I have no idea.
And one more thing, maybe even more important than going over board on the de-oxygenation front is the quality of your iron sources. If the F2 is already oxidised further (and isn’t actually F2 any more) then you are in a way actively adding the Oxygen you are trying to avoid. The FeCl2 should be white to green (depending on H2O amount) with little to no hint of orange.
I hope this has helped, even just a little.Cheers
Tim M
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