bluamine
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Can I use Ca(OH)2 to produce Al₂O₃?
Hi guys (or girls though I think they don't exist here yet lol)
I would like to make some alumina so I need to make some aluminium hydroxide before. I want forum experts to tell me what is the possibility to use
calcium hydroxide instead of sodium hydroxide.
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ave369
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They do exist here.
I don't think calcium hydroxide will work. But it can be used to make sodium hydroxide. Make limewater and add sodium carbonate. A precipitate of
calcium carbonate will fall, and you will have a solution of sodium hydroxide which can be used to make alumina.
Smells like ammonia....
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blogfast25
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Mixing a slurry of Ca(OH)2 with the solution of an Al salt should work:
3 Ca(OH)2(s,aq) + 2 AlCl3(aq) === >3 CaCl2(aq) + 2 Al(OH)3(s)
It works because Al(OH)3 is far more insoluble than Ca(OH)2 (which has some solubility). Then filter off the CaCl2 and wash the filter cake
thoroughly.
I'm not claiming this is a particularly practical method but in principle it should work with any Al salt provided the Ca equivalent is water soluble.
An excess of Ca(OH)2 would lead to some aluminate formation and thus product losses.
[Edited on 8-10-2015 by blogfast25]
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bluamine
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Quote: Originally posted by ave369  | They do exist here.
I don't think calcium hydroxide will work. But it can be used to make sodium hydroxide. Make limewater and add sodium carbonate. A precipitate of
calcium carbonate will fall, and you will have a solution of sodium hydroxide which can be used to make alumina. |
well I tried that but didn't get an important amount of NaOH
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bluamine
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| Quote: Originally posted by blogfast25 |
I'm not claiming this is a particularly practical method but in principle it should work with any Al salt provided the Ca equivalent is water soluble.
An excess of Ca(OH)2 would lead to some aluminate formation and thus product losses.
[Edited on 8-10-2015 by blogfast25] |
Of course it is not.. provided that I need to heat CaCO3 at 1000° temp.. So I'd better wait until I have my mercury cell to make that
[Edited on 8-10-2015 by bluamine]
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Bert
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Thread Moved
8-10-2015 at 15:36 |
bluamine
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By the way, can anyone explain to me why does aluminum chloride have two different colours in the picture on the link below:
https://en.wikipedia.org/wiki/Aluminium_chloride
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gdflp
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Wildly off-topic, but it's because the yellow one is
contaminated with iron(III) chloride.
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Artemus Gordon
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| Quote: Originally posted by bluamine | | Quote: Originally posted by ave369 | They do exist here.
I don't think calcium hydroxide will work. But it can be used to make sodium hydroxide. Make limewater and add sodium carbonate. A precipitate of
calcium carbonate will fall, and you will have a solution of sodium hydroxide which can be used to make alumina. |
well I tried that but didn't get an important amount of NaOH |
You would need a large quantity of water. I have made limewater a number of times and I find that much less than a teaspoonful of lime will saturate a
liter of distilled water. So you would need to make maybe a hundred liters of limewater to obtain more than a few grams of Sodium Hydroxide.
BTW, don't try to use lab filter paper to catch the excess lime, it clogs the paper and your flow rate is ridiculously slow. I find that a #2 coffee
filter held in one of those cup-top plastic cones works great.
[Edited on 11-10-2015 by Artemus Gordon]
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