Pulling air through saturated kalk

[Dkeller_nc]

I guess sometimes there are very good reasons why professionals do the things that they do the way that they do them.

Yeah, the only thing I haven't been able to puzzle out is the reaction chemistry that occurs to make carbon monoxide in these systems if you don't have moisture in the canister. If you happen to know why this is, I'm all ears. Maybe "SleepyDoc" could shed some light on it, since he's an anesthesiologist, and as I understand it, CO2 scrubbing is part of the deal with anesthesia.

 

[Dkeller_nc]

....jumping to the end, I saw 30 sumthin lbs of the dry/air use stuff on eBay for like $100 ... not sure if at that price it is cheaper than aqueous solution of sodium hydroxide but probably easier....
...Anytime there is a chance we can skip the lab/pharmaceutical grade stuff and use cheap off the shelf solution bears a lil exploration
-- So where does cost vs. practical intersect? ... I was sorta hoping for chemical nirvana; cheap and easy; dump half a bag of pickling lime in a 5g bucket, hook a skimmer inlet to the top and voila, no more CO2...come back every 48-72 hrs and recharge for $1.50

Well, after Jim corrected my goof from this morning, it seems a lot more worth messing with, though I think I'd fall over if someone said I'd have to do a maintenance task on my reef that involved hefting a 5 gallon bucket every 48 hours.

There's been a fair amount of discussion about where to get the soda lime absorbent in bulk for cheap; it seems there's a lot of sources that sell it for veterinary anesthesia purposes - here's one such source. Another purpose is for scuba rebreathers, but it appears that the material sold for that purpose is non-indicating, as the indicator isn't allowed by Navy dive specifications.

 

[JimWelsh]

Yeah, the only thing I haven't been able to puzzle out is the reaction chemistry that occurs to make carbon monoxide in these systems if you don't have moisture in the canister. If you happen to know why this is, I'm all ears. Maybe "SleepyDoc" could shed some light on it, since he's an anesthesiologist, and as I understand it, CO2 scrubbing is part of the deal with anesthesia.

I found this, which suggests that perhaps that's only an issue in the presence of "halogenated anesthetics" (like @Sleepydoc's avatar)? I'll keep looking.

 

[JimWelsh]

Another.

 

[JimWelsh]

Jackpot!!!

 

[JimWelsh]

And still more paydirt. Tagging @Sleepydoc again.

 

[Dkeller_nc]

After reading these, the carbon monoxide production makes a lot more sense. It was hard for me to imagine that CO2 in the breathing circuit could be reduced to CO, much less be affected by the presence of water vapor. I do know that really strong reducing agents like lithium aluminum hydride can do this; the reduction of CO2 fire extinguishers and subsequent deflagration of the hydrogen given off is quite spectacular. But I wouldn't think that simple hydroxide radical would be anywhere near enough to reduce CO2.

 

[Sleepydoc]

Wow - who know all that stuff I read in textbooks would actually be useful! Thanks for digging up the articles, Jim. I knew that anesthetics could react with desiccated CO2 absorbents to make CO, but I'd never actually seen the chemical reactions. What's kind of scary is that hydrofluoric acid is one of the byproducts. That's nasty stuff! Regardless, the reaction requires a halogenated anesthetic, so unless you're anesthetizing your fish, you're probably safe!

 

[Sleepydoc]

Argon be all, "What am I -- chopped liver!?!?"

Well, if you’re in to noble gases, Xenon can be used as an anesthetic..