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Topic: Choice of Chemical for Scrubbing CO2  (Read 6695 times)

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Offline Sreeni

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Choice of Chemical for Scrubbing CO2
« on: June 07, 2010, 01:56:41 PM »
Which among the following is apt for scrubbing carbon dioxide considering all the below mentioned parameters...

       * cost
       * availability
       * dissociation constant
       * effectiveness in removal  - solubility
       * molecular mass - so that mass of a system may be minimised having optimum values for all other parameters


Chemicals : Lithium hydroxide, Sodium hydroxide or Calcium hydroxide

 :) :) :)
  

Offline skyjumper

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Re: Choice of Chemical for Scrubbing CO2
« Reply #1 on: June 08, 2010, 07:00:19 PM »
Sodium Hydroxide is the cheapest, and most available. Ca(OH)2 is not water soluble, and has a high molar mass.

Offline mevans

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Re: Choice of Chemical for Scrubbing CO2
« Reply #2 on: June 09, 2010, 06:51:58 PM »
I agree, sodium hydroxide is cheap and will scrub CO2. I tested this one time with a ph meter and CO2 produced from vinigar and baking soda. The reading on the ph meter dropped from 14 to 11 in around two minutes. This wasnt much but i was only using a .1M sodium hydroxide solution. I bet a 15+ molar solution would be a fantastic scrubber

Offline Sreeni

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Re: Choice of Chemical for Scrubbing CO2
« Reply #3 on: June 10, 2010, 01:04:46 PM »
What is the opinion about LiOH? Its also a strong base with lower molar mass and i found that it was used in spacecrafts for scrubbing..

Offline mevans

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Re: Choice of Chemical for Scrubbing CO2
« Reply #4 on: June 10, 2010, 03:43:26 PM »
This would probably work as well. But, lithium hydroxide is much more expensive than sodium hydroxide. and since sodium is more reactive than lithium, i would imagine that it would be more reactive towards the co2. if this is true, than you might consider trying potassium hydroxide becuase it is morre reactive than sodium hydroxide but it is slightly more expensive. And if you are somehow able to get ahold of caesium hydroxide, that would probably work the best but even if you mannage to find someone who is willing to sell it to you, it will be rediculously expensive.
Get someone to confirm that naoh would work better than lioh. Im 90% sure but not positive
Alternitavely, if you have a ph meter you could test a .1M solution of each. To do this you would need to but an equal ammount of vinigar in 3 flasks. each flask would need to have a 1 holed stopper with a peice of glass tubing on top. The tubing would need to be bent at a sharp angle so it could be submersed in a beaker. Put .1M solutions of lioh, naoh and caoh in 3 different beakers make sure the volume in each beaker is the same. Then, add an equal ammount of baking soda to each of the 3 flasks and put the 1 holled stopper on. each in each beaker, put the other end of the glass tubing in the base solution. the baking soda and vinigar reaction releases CO2 which travels through the glass tubing and into the base solution where it changes the hydroxide to a carbonate. Let the reactions run untill no more CO2 is produced and then take the pH of each solution. which ever one has a lower pH absorbed the most CO2 and therefore is the best CO2 scrubber. In order to get good ph reading though, you will need an electronic pH meter. 

Offline typhoon2028

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Re: Choice of Chemical for Scrubbing CO2
« Reply #5 on: June 10, 2010, 04:16:40 PM »
Can you use a packed column?  This would work better.  You would get better mass transfer.

Offline Sreeni

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Re: Choice of Chemical for Scrubbing CO2
« Reply #6 on: June 13, 2010, 02:19:58 AM »
Packed column will pose trouble. The carbonates formed will get precipitated and hence the flow will be affected.... More will be the pressure drop...

Offline typhoon2028

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Re: Choice of Chemical for Scrubbing CO2
« Reply #7 on: June 14, 2010, 09:33:40 AM »
Sodium Carbonate is soluble in water, but I am unsure of how soluable it is in NaOH. 

Slow bubbling through a diffuser or air stone the bottom of tall column of NaOH (aq) would be best.

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