Info Reusable Covalent Oxide Framework (COF) for removing CO2 from industrial exhaust (and maybe divers?)

[missionmtb]

Carbon dioxide capture from open air using covalent oxide frameworks (Yaghi, Nature)

This study is mostly focused on industrial exhaust with CO2 contents of ~20% (where the moolah is) but they allude to human breath with experiments showing efficient capture at 4% CO2. What's cool about this stuff is you can remove the CO2 from it and use it again (at elevated temps and/or vacuum conditions I think). This is great for industrial applications for sequestration, or maybe for us in having a reusable scrubber!

I did some initial math using google numbers and looks like it has about the same weight vs. CO2 absorption as sofnolime (could be totally wrong here). If so it wouldn't be smaller/lighter but at least not consumable.

Just like sodalime it works better with moist air, like our breath.

Pretty exciting stuff.

-M

 

[Johnoly]

I don't think testing concentrations have been done on humans in a closed loop configuration. COF-999 contains amine which is formed from ammonia. Depending on PPM's of all those different components can be pretty dangerous at 200ft deep and well back in a cave, and unable to surface immediately. Most of the scubadiver's {general} equipment and prototypes have been previously tested by the Navy. If they aren't using COF-999, then nobody in public diving is going to take a chance on it either.

 

[missionmtb]

I don't think testing concentrations have been done on humans in a closed loop configuration. COF-999 contains amine which is formed from ammonia. Depending on PPM's of all those different components can be pretty dangerous at 200ft deep and well back in a cave, and unable to surface immediately. Most of the scubadiver's {general} equipment and prototypes have been previously tested by the Navy. If they aren't using COF-999, then nobody in public diving is going to take a chance on it either.

I agree this material certainly hasn't been tested in a diving application as the paper is aiming, I think, more at flue gas CO2 sequestration. Thanks for reiterating.

In the paper the material is exposed to most of the gases you would see in a scuba breathing application (I don't see helium though, for example) without degradation of the material, so not sure we'd see ammonia evolve from it just from exposure to breath. Interestingly, it states that it is highly selective for absorption of CO2, suggesting it doesn't much interact with say oxygen for example. The paper also states the material is thermally stable up to pretty high temperatures during desorption (100C!) without degraded performance over 1000 cycles, suggesting the amine groups are at least pretty thermally stable as well. You might be right though as there are other conditions in a diving application that may present challenges (elevated ambient pressure, exposure to sea water, etc.). I also wonder if any other materials typically present in a rebreather breathing loop (polyisoprene, POM, SST, silicone, aluminum etc.) would have an interaction with COF-999? In any event, looking quickly at amine exposure to respiratory systems it doesn't look quite as bad as, say, sodium hydroxide though should a caustic cocktail-like flood occur.

I think it would be really cool if NEDU (or one of the many other dive technologists out there, looking at you Stone Aerospace) considered testing a prototype incorporating this! As with most research like this it's probably years away from practical applications, let alone recreational ones. A boy can dream...

 

[DerTaucher]

As a chemist I'm really interested in seeing what these new materials could do for rebreathing diving. I'm not rebreather certified, but the caustic cocktail issue worries me and I believe there has be a better solution. The paper on COF-999 shows a promising material for CO2 adsorption and would be nice if rebreather companies started funding research toward new scrubber materials.