Lithium Hypochlorite Chemistry

[TreeFiter]

I've been thinking about Lithium Hypochlorite, and I'm wondering why it doesn't have any of the negative side effects we see from Calcium Hypochlorite. I realize there is a difference between Lithium and Calcium, but shouldn't there be a risk of forming Lithium Carbonate once the water becomes saturated with Lithium?

 

[JoyfulNoise]

Yes, but the solubility of lithium carbonate is much much greater than calcium carbonate -

CaCO3 solubility = 0.013 g/L at 25C

Li2CO3 solubility = 12.9 g/L at 25C

So the solubility difference is a factor of 1000!


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[TreeFiter]

Yes, but the solubility of lithium carbonate is much much greater than calcium carbonate -

CaCO3 solubility = 0.013 g/L at 25C

Li2CO3 solubility = 12.9 g/L at 25C

So the solubility difference is a factor of 1000!


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Interesting. I did a quick google search on Lithium Carbonate, and the descriptions I found made it sound like it was not very soluble. I guess relative to Calcium Carbonate it is.

So does this mean that it is possible to cloud the water with Lithium Carbonate, but very unlikely because of how much Lithium would be needed to do so?

 

[chem geek]

Very, very unlikely, as in you will never see it happen. At usual pool pH and TA calcium carbonate saturation occurs with the CH at roughly 300 ppm. With lithium carbonate being 1000 times more soluble, you'd have to get your lithium levels to the 300,000 ppm range (in calcium carbonate weight units) and as you know even using chlorinating liquid or bleach for years doesn't get the salt level anywhere near that high.

You need to think of lithium more like sodium than calcium. Compare the solubilities and solubility products in this link where I list the carbonates in order of least to most soluble (sometimes solubility is higher than the solubility product implies due to ion pairs):

Mercury(I) Carbonate 0.000045 g/L solubility; K_SP 9.52x10^-15
Lead(II) Carbonate 0.0011 g/L solubility; K_SP 7.4x10^-14
Cobalt Carbonate K_SP 1.4x10^-13
Manganese(II) Carbonate K_SP 1.8x10^-11
Iron(II) Carbonate K_SP 3.2x10^-11
Copper(II) Carbonate K_SP 1.4x10^-10
Nickel(II) Carbonate K_SP 6.6x10^-9
Strontium Carbonate 0.01 g/L solubility; K_SP 4.59x10^-9
Zinc Carbonate 0.01 g/L solubility; K_SP 1.4x10^-11
Calcium Carbonate 0.014 g/L solubility; K_SP 2.8x10^-9
Barium Carbonate 0.02g/L solubility; K_SP 1.03x10^-8
Silver Carbonate 0.033 g/L solubility; K_SP 8.1x10^-12
Magnesium Carbonate 0.106 g/L solubility; K_SP 3.5x10^-8
Lithium Carbonate 15.4 g/L solubility; K_SP 2.5x10^-2
Sodium Carbonate 211 g/L solubility; K_SP 1.2
Potassium Carbonate 1120g/L solubility; K_SP 2130
Ammonium Carbonate 1000g/L solubility; K_SP 4520

You can see that magnesium carbonate is around 7-8 times more soluble than calcium carbonate which is why with most hard water you see calcium carbonate scale first. It's possible to have water high in magnesium and not calcium in which case you could get magnesium carbonate scale but that is unusual. You can see the very large jump in solubility going from magnesium to lithium. For practical purposes, you can consider lithium, sodium, and potassium carbonates to be very soluble in pool water at concentrations you could have in such pool water. You can also see that there are many metals that can precipitate with carbonate including zinc, nickel, copper, iron, manganese and cobalt, but metal ion concentrations are far lower so in practice you don't see zinc carbonate and for the other metals you're more likely to see oxides-hydroxides of those that are less soluble than the carbonates.

 

[JoyfulNoise]

I think your bigger concern is the cost premium. Based on Leslie's web prices -

24lbs of Li-hypo (35% available chlorine) is $130

24lbs of Cal-hypo (73% available chlorine) is $105

($130/$105) x (0.73/0.35) = 2.56

So your paying more than 2-1/2 times as much for the same amount of chlorine. That's awfully high premium to pay just to avoid managing calcium scale.


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[TreeFiter]

I think your bigger concern is the cost premium. Based on Leslie's web prices -

24lbs of Li-hypo (35% available chlorine) is $130

24lbs of Cal-hypo (73% available chlorine) is $105

($130/$105) x (0.73/0.35) = 2.56

So your paying more than 2-1/2 times as much for the same amount of chlorine. That's awfully high premium to pay just to avoid managing calcium scale.


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The cost is certainly a drawback. The only reason I'm considering it is because I've started to see Calcium cause problems in some pools. Its not so much a scale issue as it is a cloudy water problem. Of course my other option would be Liquid Chlorine, but its difficult to carry around in the quantities I would need.

In my situation the cost isn't necessarily a problem for me, but I'm sure there will be some push back from customers when they see they are paying twice as much for chlorine. It would only be used occasionally, assuming we are doing things right.

 

[JoyfulNoise]

The cost is certainly a drawback. The only reason I'm considering it is because I've started to see Calcium cause problems in some pools. Its not so much a scale issue as it is a cloudy water problem. Of course my other option would be Liquid Chlorine, but its difficult to carry around in the quantities I would need.

In my situation the cost isn't necessarily a problem for me, but I'm sure there will be some push back from customers when they see they are paying twice as much for chlorine. It would only be used occasionally, assuming we are doing things right.

Well, your other option is to get SCBA certified and start offering chlorine gas injection service. Nothing beats pure chlorine gas!


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[TreeFiter]

Well, your other option is to get SCBA certified and start offering chlorine gas injection service. Nothing beats pure chlorine gas!


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Scary stuff! I'll stick with really expensive grannulars.

 

[n240sxguy]

Well, your other option is to get SCBA certified and start offering chlorine gas injection service. Nothing beats pure chlorine gas!


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I've wondered what kind of PPE the pool companies use when they mess with chlorine gas. We use it at work, and you don't want to be around it without protection.


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[JoyfulNoise]

I've wondered what kind of PPE the pool companies use when they mess with chlorine gas. We use it at work, and you don't want to be around it without protection.


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Yeah, tell me about. I used to work with Excimer lasers (KrF and XeCl) and all halogen gasses had to be stored and used inside fully automated gas cabinets with double-walled stainless steel tubing going out to the equipment. There were also chemical gas sensors in the room that had to be tested monthly. When we changed cylinders out, the gas cabinet purged and sealed all the lines BUT we still had to wear SCBA equipment and be fully trained.

I see the Pima Chemical trucks around here all the time with their chlorine and CO2 cylinders in the back. I drive 200ft behind them


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