What are your thoughts on that "New material (that) steals oxygen from air"

[dberry]

OK, my late reply to a very old thread... My own research field isn't very far removed from the subject of this article about the "oxygen stealing material", and I just took the time to read the original article. It's a nice piece of science, BUT you folks should realize something before planning new scuba gear based on this cobalt complex. The compound holds about 3-6% it's weight in oxygen. In other words, you'd need ca. 20x the mass of compound for a given mass of O2.
Using very rough calculations: A standard Al80 @ 3000psi carries about 6 pounds of air, which is about 1.2 lbs of O2. That means you'd need ~24 lbs of the cobalt compound to store the O2 in 1 AL80. That's excluding the hardware needed to heat the stuff to release the O2. Since a an Al80 weighs ~31 lbs, it's not obvious you're going to save much weight. And if you use cave fills the savings are even less. Finally, it would take about 33lbs of the stuff to store the equivalent of a 19cf bottle of 100% O2 (again without equipment to get the O2 back out.)

Like I said, it's a neat bit of science, and there are certain novel aspects to the work from a scientific standpoint, but the technological utility is a bit oversold in the paper (which is actually quite normal when you need to secure future funding.)

PS In case any science-minded (or non-American) folks were wondering about a chemistry prof giving results in lbs, I translated the values to imperial units for the convenience of the non-metric readers. The 'murican way of designating cylinder is almost too stupid for words, but that's another battle.

 

[REVAN]

Thanks for the mass calculations, dberry. Are you pretty sure you got the numbers about right? Some of the articles around this subject have made it sound much more O2 dense than what you are saying here.

I'd say that it doesn't actually need to hold as much O2 as a standard 80 to be useful. If you can store and release enough O2 to to give you 5 to 7 minutes of submerged time and then surface to recharge the O2 in the same amount of time or less, it would still be enormously useful, especially if the equipment were small (like a 13 cubic foot pony bottle small). Truth is, we don't really need to be down for an hour at a time. If we could operate like a freediver with some equipment that allows for mimicking the capability of an inhumanly long breath hold, it could be a real game changer; like the end of recreational scuba as we know it kind of game changer.

However, from what I have read, it doesn't sound like this material is likely to be able to function like this in a practical machine. If you need to heat and cool it to activate the modes, that may not make for a practical machine for operation in the ocean. Any thoughts?

PS - On reflection, this would not be a pressure vessel like an air tank. It could be volumetrically larger than a 13 without being more cumbersome than a 13 just by changing the shape of the container to be conformal to a diver. We would need to start thinking outside of the cylinder, so to speak.

 

[Steve_C]

Hmmm. Mixing hydrogen and oxygen. Helium is pretty inert. Hydrogen is much less so.

 

[REVAN]

Hmmm. Mixing hydrogen and oxygen. Helium is pretty inert. Hydrogen is much less so.

It's been done before, but it is explosive in the wrong ratios (or right ratios depending on your perspective). It would only work for really deep dives where the O2 content is too low to support combustion, but the total pressures are high enough to create a life sustaining PPO2. Shallow you would have to use nitrogen or some other diluent that will not burn explosively like H2 in the presence of near stoichiometric amounts of O2.

 

[dberry]

Thanks for the mass calculations, dberry. Are you pretty sure you got the numbers about right? Some of the articles around this subject have made it sound much more O2 dense than what you are saying here.

Are my numbers about right? I think so. If anything I was trying to be generous. There is a plot in the original paper showing how they can repeatedly absorb and release O2 by varying the temperature from 30 C (86 degF) to 140 C (338 F). A sample of complex starts out fully loaded with O2; call that mass "100%". Heat it to 140C and the mass drops to 95.5% of the original, or a loss of 4.5%. However, that is not all O2, as they authors explain it's also losing a bit of solvent and water the first time. After cooling back to 30C under O2 the mass goes back up, but not quite to 100%, only to 99% (because the solvent / water isn't being replaced.) So in truth, only 3.5% of the original mass was due to bound O2 being released. They repeat the temperature cycling 9 more times and the 3.5% O2 (by mass) is fairly consistent after the 1st run.

Now the mass % of O2 theoretically possible can be calculated from the molecular formulas of the various cobalt compounds they prepared - they're all very similar, but with different anions in the structure. I used a value of 5% in the calculations I posted mainly for convenience (5% means 1/20th of the mass is O2), but the actual numbers for their compounds are worse. For example the best case compound they report has a molecular weight of 1870 Dalton (after removing all the water) and contains two molecules of O2 (32 Dalton each). 64 / 1870 = 3.4%.

OK, so my 5% was actually much too generous. Let's call it 3.3%, which means you need 30 times the amount of compound for a given mass of O2 (not 20x). It seems from the paper that O2 loss kicks in a little below 100 C for some of the derivatives, so you'd need to have a way to heat the stuff to ca. 200 deg F (while underwater). Oh, and don't forget a power supply (batteries) for the heater.

Another issue: the release of O2 at even 100 C was almost certainly measured under a flow of N2 (or He or Ar). It's not at all clear what kind of equilibrium pressure of pure O2 you could build up without a flow of diluent. Maybe not a problem with a CCR (where you keep most of the N2 and/or He around), but picture some poor open-circuit diver sucking like crazy on the (200 deg F) device for dear life to get little sips of O2. An old saying about "sucking the chrome off a trailer hitch" is popping into my head for some reason

I'd say that it doesn't actually need to hold as much O2 as a standard 80 to be useful. If you can store and release enough O2 to to give you 5 to 7 minutes of submerged time and then surface to recharge the O2 in the same amount of time or less, it would still be enormously useful, especially if the equipment were small (like a 13 cubic foot pony bottle small). Truth is, we don't really need to be down for an hour at a time. If we could operate like a freediver with some equipment that allows for mimicking the capability of an inhumanly long breath hold, it could be a real game changer; like the end of recreational scuba as we know it kind of game changer.

However, from what I have read, it doesn't sound like this material is likely to be able to function like this in a practical machine. If you need to heat and cool it to activate the modes, that may not make for a practical machine for operation in the ocean. Any thoughts?

I'll need to think about this a bit more; I hate to be a spoil-sport / nay-sayer, but I'm not optimistic.
-Don Berry

 

[uranylcation]

OK, my late reply to a very old thread... My own research field isn't very far removed from the subject of this article about the "oxygen stealing material", and I just took the time to read the original article. It's a nice piece of science, BUT you folks should realize something before planning new scuba gear based on this cobalt complex. The compound holds about 3-6% it's weight in oxygen. In other words, you'd need ca. 20x the mass of compound for a given mass of O2.
Using very rough calculations: A standard Al80 @ 3000psi carries about 6 pounds of air, which is about 1.2 lbs of O2. That means you'd need ~24 lbs of the cobalt compound to store the O2 in 1 AL80. That's excluding the hardware needed to heat the stuff to release the O2. Since a an Al80 weighs ~31 lbs, it's not obvious you're going to save much weight. And if you use cave fills the savings are even less. Finally, it would take about 33lbs of the stuff to store the equivalent of a 19cf bottle of 100% O2 (again without equipment to get the O2 back out.)

Like I said, it's a neat bit of science, and there are certain novel aspects to the work from a scientific standpoint, but the technological utility is a bit oversold in the paper (which is actually quite normal when you need to secure future funding.)

PS In case any science-minded (or non-American) folks were wondering about a chemistry prof giving results in lbs, I translated the values to imperial units for the convenience of the non-metric readers. The 'murican way of designating cylinder is almost too stupid for words, but that's another battle.

Very well said. Have worked on crystal engeering/porous materials/coordination chemistry...for years, I would say this kind of selective absorption is neat but not that unusual. Do not have access to full paper right now, but if I understand it correctly, structural resolvation of the adsorption/desorption process at molecular level is of more academic interests and value. And I can't agree more how researchers would try to 'sale' their results for better acceptance and/or future funding. During the years I have synthiszied materials able to decompose water pollutents under sunlight, or to recycle uranium from spent nuclear fuels, although the possibility to utilize them in real life is rather remote to be most optimistic, those functions are still the major 'sale point' for them to be accepted in scientific journals and to secure fundings for my professors. Hopefully those publications will not give anyone outside of academic circle any false impression that water pollution or nuclear wastes or any other issues are not global problems anymore...