Calcium Hack Thread

[DirtMechanic]

No. I'm wondering what the pH of the calcium acetate solution would/should be when the eggshells are finished dissolving and the vinegar is completely used up or converted over to acetate. I thought that was what you were referring to in post #3.

All I have is a soil stick. I will be curious to know myself.

 

[YumYum]

All I have is a soil stick. I will be curious to know myself.

Well I can let you know what my liquid comes up to. I have phenol red and bromothymol blue reagents so as long as it is in the 6.2-7.8 range. Mine is on day 2 and still bubbling.

 

[DirtMechanic]

Well I can let you know what my liquid comes up to. I have phenol red and bromothymol blue reagents so as long as it is in the 6.2-7.8 range. Mine is on day 2 and still bubbling.

I am kinda thinking that dangerous super dry lime might work well here. Quicklime? The one that gets hot when you add water?

 

[YumYum]

I am kinda thinking that dangerous super dry lime might work well here. Quicklime? The one that gets hot when you add water?

Bound to get some kind of reaction with calcium hydroxide and vinegar. Probably would work if it doesn't blow up.

Or are you suggesting to just add water to it to get water soluble calcium? Sounds like you may have already been down this road.

 

[DirtMechanic]

Bound to get some kind of reaction with calcium hydroxide and vinegar. Probably would work if it doesn't blow up.

Or are you suggesting to just add water to it to get water soluble calcium? Sounds like you may have already been down this road.

No just fascinated by lime and its history. @zigs worked the old lime mortar ruins as a repair person and has neat observations. Not sure if it was he that pointed out to me that while they dry and cook the limestone, once you start adding water to the dehydrated result it works to become stone again. Maybe this proclivity is what the author was meaning about calcium becoming unavailable after it sits in the soil mix for a while. The chemistry of adding water has such an in rush it can produce a blistering heat so vinegar being mostly water may well do the same thing if, like you say, it does not blow up.

 

[Ruderunner]

Reactions between acids and bases always release energy. How much, how fast varies wildly. But the safe practice is to add acids slowly to bases. Apparently bases are less reactive.

 

[zigs]

No just fascinated by lime and its history. @zigs worked the old lime mortar ruins as a repair person and has neat observations. Not sure if it was he that pointed out to me that while they dry and cook the limestone, once you start adding water to the dehydrated result it works to become stone again. Maybe this proclivity is what the author was meaning about calcium becoming unavailable after it sits in the soil mix for a while. The chemistry of adding water has such an in rush it can produce a blistering heat so vinegar being mostly water may well do the same thing if, like you say, it does not blow up.

Yep, don't add water to calcium hydroxide unless you're wearing PPE and are good at running away, it boils pretty much straight away

 

[DirtMechanic]

Yep, don't add water to calcium hydroxide unless you're wearing PPE and are good at running away, it boils pretty much straight away

Thats nice, because I can see this event of water and calcium hydroxide fighting it out which should of course leave the now lonely and purified acetic acid to be blown onto me? Hopefully it can be enamored with the calcium instead of my skin.

 

[YumYum]

I put 50 g of crushed eggshells that where rinsed and microwaved for almost 2 min in a quart jar and added 500 g of 5% distilled white vinegar. I saw 10:1 was suggested so that is where I'm going to start. I think that is going to be too much vinegar and the final product will be acidic which means too much vinegar.

I let it sit for 14 days, swirling a couple times a day, strained the liquid. The pH of the liquid tests lower than 5.5. I don't have anything to check lower than that. The vinegar is clearly not used up and there are still a bunch of eggshells left so I assume more time is needed to soak but how much, years?. Even with the solution I have now, there is no telling the strength of the calcium acetate solution. I dont think it is very strong.

 

[DirtMechanic]

I let it sit for 14 days, swirling a couple times a day, strained the liquid. The pH of the liquid tests lower than 5.5. I don't have anything to check lower than that. The vinegar is clearly not used up and there are still a bunch of eggshells left so I assume more time is needed to soak but how much, years?. Even with the solution I have now, there is no telling the strength of the calcium acetate solution. I dont think it is very strong.

I found a government health pub saying eggshell has .38g (380mg) calcium per gram.
By weight, to match it you need to know the details on the acetic acid in the vinegar. Generally I think you need more eggshells.

 

[YumYum]

Eggshells are 94% calcium carbonate so they are 38% calcium which is what you said. There are other things like magnesium. I guess those dissolve too into something. Not really sure what.

Just guessing by looking but it appears at least half the eggshells are left so that really dilutes the final product. If you use more eggshells or less vinegar, it is going to take alot longer to dissolve the eggshells. No matter what it will still be a guess of the amount of calcium in it. I'm not really seeing this worth doing unless I'm missing something.

 

[DirtMechanic]

Just as far as understanding how to get a more neutral pH if that is even possible I weighed an eggshell at 8.32g. The offsetting amount of vinegar would balance against this number.

And no, I would also attempt to use a big volume bagged product like garden lime. Let compost be compost right?

What I notice about your effort is how the returns seem to dwindle as it acts. Like you say slowing to infinity.

The specific gravity of a 5% solution of acetic acid is 1.006 g\mL. Practically same as water at 1g\mL

Is it right to say you need 166.4mL of vineager to present my eggshell with 8.32 g acetic acid in a 5% vinegar. Thats a lot.

 

[YumYum]

What I notice about your effort is how the returns seem to dwindle as it acts. Like you say slowing to infinity.

Yes. Reaction seems fast at first then slows.

 

[YumYum]

Is it right to say you need 166.4mL of vineager to present my eggshell with 8.32 g acetic acid in a 5% vinegar. Thats a lot.

I don't know. Maybe one can work backwards from "100% Calcium Acetate" and figure that up. My brain hurts.

 

[YumYum]

Ok. I'm not 100% this is correct but this is what I came up with.

100% calcium acetate is 25% calcium and 75% acetate by weight.
So you need 3 times the weight of acetate as you do calcium.

100g of eggshells = 38g of calcium so you need 114g of acetate. (38 * 3 = 114)

Vinegar is 5% acetic acid which should equal 4.92% acetate. *Acetic acid has an extra hydrogen atom that has to be subtracted.
So you need 2,317g of vinegar per 100g of eggshells. (114g / 0.0492 = 2317)

So that is a 23:1 ratio of vinegar:eggshells by weight.

My experiment was 10:1 and was still acidic so it wasnt finished breaking down the eggshells which was evident by the eggshells leftover. More vinegar may work faster than less vinegar too but I suspect it will still take a long time to completely dissolve the eggshells to get the full benefit of calcium. If not you may only be extracting a few ppm of calcium and probably not worth the effort.