I have no chemistry skills past HS, so what would be in the gas? edited to add; appreciate any thoughts
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Argon be all, "What am I -- chopped liver!?!?"Nitrogen and oxygen. The kalkwasser, depending on how efficient the air/kalkwasser mixing is, will pull all of the CO2 out of the air that's bubbled through the solution. That's why kalkwasser solutions that are left to stand for a period of time will develop a thin skin of precipitated calcium carbonate on the surface.
Ha! Well, true, I didn't count the noble gases nor the trace amounts of radon from radioactive decay, but I figured we could ignore those since they're such a small percentage.Argon be all, "What am I -- chopped liver!?!?"
What are those rigs called where a jar has a lid and a pipe that extends into the liquid and you draw the air from the top? (the air gap between the surface and the lid)? So whatever that thing is called, I was thinking I could feed my skimmer that air from the top of my semi hermetically sealed Kalk res.....assuming you could even rig a skimmer to have enough draw to pull some gas through a liquid ...Nitrogen and oxygen. The kalkwasser, depending on how efficient the air/kalkwasser mixing is, will pull all of the CO2 out of the air that's bubbled through the solution. That's why kalkwasser solutions that are left to stand for a period of time will develop a thin skin of precipitated calcium carbonate on the surface.
But, argon is in greater concentration than CO2, which you did decide to mention.
Slow down a minute, there, sparky! In aqueous solution, that is correct, but we're talking about CO2 concentration in air, where "PPM" has a different meaning. When describing gasses, "PPM" is referring to a mole fraction (PPMV), not mg/L. The average molar mass of air is 28.96 g/mol, and the density of air can be taken as 1.292 g/L, so each liter of air contains only 1.292 / 28.96 = 0.0446 moles of air, of which only 400 / 1,000,000 is CO2, so that's 0.0446 * 0.0004 = 0.00001784 moles of CO2 per liter of air. The weight of that CO2 is 0.00001784 * 44 = 0.000785 grams, or 0.785 mg. The assumption you made put that value at 400 mg, so the actual adsorbing capacity of the kalk (in terms of the number of liters of air that can be "scrubbed") is around 500 times your estimate, I believe. Reference for the air molar mass and density numbers is here: https://www.engineeringtoolbox.com/molecular-mass-air-d_679.htmlSince 400 ppm is 400 mg/L
What are those rigs called where a jar has a lid and a pipe that extends into the liquid and you draw the air from the top?
So, if someone is using your more concentrated 2-part based on sodium hydroxide instead of sodium carbonate for dosing, then they could get the benefit of CO2 scrubbing of their skimmer intake, without adversely affecting the alkalinity of the 2-part (since we know that adding CO2 to a solution affects pH, but not carbonate alkalinity), unless the Na2CO3 concentration reaches saturation, yes?This will work to some extent, but I might just use a sodium hydroxide solution. Far more concentrated (so faster acting on CO2 entering it), needs no stirring, and probably cheaper.
Slow down a minute, there, sparky! In aqueous solution, that is correct, but we're talking about CO2 concentration in air, where "PPM" has a different meaning. When describing gasses, "PPM" is referring to a mole fraction (PPMV), not mg/L. The average molar mass of air is 28.96 g/mol, and the density of air can be taken as 1.292 g/L, so each liter of air contains only 1.292 / 28.96 = 0.0446 moles of air, of which only 400 / 1,000,000 is CO2, so that's 0.0446 * 0.0004 = 0.00001784 moles of CO2 per liter of air. The weight of that CO2 is 0.00001784 * 44 = 0.000785 grams, or 0.785 mg. The assumption you made put that value at 400 mg, so the actual adsorbing capacity of the kalk (in terms of the number of liters of air that can be "scrubbed") is around 500 times your estimate, I believe. Reference for the air molar mass and density numbers is here: https://www.engineeringtoolbox.com/molecular-mass-air-d_679.html
So, if someone is using your more concentrated 2-part based on sodium hydroxide instead of sodium carbonate for dosing, then they could get the benefit of CO2 scrubbing of their skimmer intake, without adversely affecting the alkalinity of the 2-part (since we know that adding CO2 to a solution affects pH, but not carbonate alkalinity), unless the Na2CO3 concentration reaches saturation, yes?
EDIT: I did the math, and even when using the higher-pH 2-part recipe at 1.5 times, or B-Ionic, strength, and even if all of the hydroxide got converted to carbonate, the Na2CO3 concentration would still be only around 50% of a saturated solution at room temperature.
EDIT2: But, then it dawns on me that a tank running like this would see a nice increase in pH whenever the alk portion of the 2-part was refilled, that would then drop continuously as both the CO2 adsorbing capacity of the solution decreased, and also as the OH / CO3 ratio of the solution being dosed drops. Probably not a good idea to do this. I'll show myself out now.
That means that 0.023 moles of CO2 will be taken up per liter of kalkwasser solution, which is 44 g/mol * 0.023 mol/L = 1 gram of CO2 per liter of solution.
Exactly what I was looking for,,, appreciate it.....yeah I strongly suspected 10tsp of kalk would be limited in CO2 absorption capacity but wasn’t sure how to figure it out.....otoh lime & water is also very cheap and easy to source and implement,,, but again had no clue if practical
edited to add; if I'm figuring this right then $3 worth of Ms.Wages (450grams) makes about 300 liters of Kalk and removes about 300 grams of CO2
...I went ahead and scaled it up to 5 gal just to see ... also since it’s bubbling I’m wondering if it works exceeding 2tsp /gal ...
it’s Sat morn nothing else to do
I guess sometimes there are very good reasons why professionals do the things that they do the way that they do them....we arrive back at the solid soda-lime absorbent solution to the problem....