For decades, soda lime has been used to capture and neutralize CO2 gas. For example, soda lime is used in air purification systems in submarines etc. to remove the buildup of CO2.
1) Soda lime is a mixture of mostly Ca(OH)2 and small amounts of either NaOH or KOH or both. (See notes below.) When exposed to CO2 and H2O, as in human exhalation, soda lime reacts with CO2 to form Ca(HCO3)2 (bicarbonate of calcium) and ultimately CaCO3 (carbonate of calcium).
2) Soda lime is cheap, but it's also dangerously caustic and corrosive. The soda lime charge can be used only once; when it reaches its reaction limit with CO2, it must be properly discarded and then replaced with a fresh soda lime charge. These factors increase its cost, usability, and desirability.
3) For amine cost, I defer to maddogs. Dr. Sayari cites a "low cost" for his wonder amine, to coin a term. I do recall seeing MEA, the amine used in 75-year old liquid-amine acid-gas capture, priced at US$1.10 per lb. or only $0.19 per ton of CO2 captured. Given that California proposes a tax of $20/ton of CO2 generated, the cost of MEA is negligible. Even the messy liquid amine soup can be recycled.
4) As to capacity of CO2 adsorption (adsorption is capture of the gas on the surface of the substrate as opposed to absorption), Sayari states that his wonder amine grafted on nano-porous silica beats all other typical CO2 adsorbents. He writes: "The adsorption isotherms, at very low partial pressure of CO2, showed one of the highest equilibrium capacities compared to other typical CO2 adsorbents such as zeolites, activated carbon and MOFs (metal-organic frameworks)."
(ed. Sayari's advance over recently touted metal-organic frameworks is especially noteworthy. MOFs are said to increase the capacity of a given pressurized hydrogen tank of a hydrogen-powered car by 300%. A pinch of a MOF contains the surface area of a football field!)
5) Sayari's dry amine structure can reportedly be "regenerated hundreds of times."
Notes:
CaO is called lime or quicklime. In the making of soda lime, H20 can be added to water to produce the majority Ca(OH)2 component. The mixture heats up real good (exothermic)! The resultant is called "slaked" lime, Ca(OH)2. Slake means quench with water as in slaking one's thirst.
Hydroxides of sodium (Natrium) NaOH and potassium (Kalium) KOH are extremely useful but dangerously caustic and corrosive. NaOH is soda lye used in making soap by adding it to oil or fat. Drano is mostly NaOH. Handle with care!
Given eons and pressure, deposits of calcinaceous diatoms and sea shells form CaCO3 or limestone. Marble is limestone that has been melted under pressure in the earth and then has cooled.
CTGI/CTUM/CCTI/LTC
These are my opinions and sentiments only. Take them for what they're worth. Do your DD. Buying stocks is risky!
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