papaya
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LiOH from carbonate?
I need some LiOH for experiments, either in the dry state or a diluted solution of known concentration (~1%), and it must be free of carbonates,
noticeable amounts of other metal cations and anions, water soluble organics.
The big problem is that the suppliers I know don't have any hydroxide pellets left, instead they can offer me Li2CO3, which is available. Is there any
way to convert it into hydroxide without much pain ? (only Ca(OH)2 comes to mind, but it's pain).
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annaandherdad
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Offhand I think any way you try to make pure LiOH from Li2CO3 is going to involve pain, not to mention that LiOH once you get it will immediately
start absorbing CO2 from the air and becoming impure, unless you keep it from the air, which is also a pain.
If it were me I'd just buy it. There is plenty available on ebay including lab grade (I'm in the US) but it's not cheap.
Any other SF Bay chemists?
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Upsilon
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Easiest tried and true method is to react it with nitric acid (or displace with something like calcium nitrate), then decomposing at around 600C to
Li2O, then in turn reacting this with water.
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Texium
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What about reacting the lithium carbonate with calcium hydroxide to precipitate calcium carbonate and then filtering? If a solution is acceptable and
you use it shortly after making it, that should be pretty easy to do.
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Upsilon
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Quote: Originally posted by zts16  | | What about reacting the lithium carbonate with calcium hydroxide to precipitate calcium carbonate and then filtering? If a solution is acceptable and
you use it shortly after making it, that should be pretty easy to do. |
He mentioned that in the OP but said it was too much of a pain. Granted, calcinating LiNO3 isn't much better. It's good if you have a steady high heat
source, but he might not want to use calcium hydroxide since both lithium carbonate and calcium hydroxide are very poorly soluble, and you would have
a slurry of these undissolved substances mixed with calcium carbonate.
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Texium
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Hmm, yeah I hadn't realized that lithium carbonate had such low solubility. I had figured it would probably be similar to sodium carbonate, but
apparently it isn't. Though theoretically, the precipitation of calcium carbonate and removal of carbonate ions from solution should allow more of the
lithium carbonate to dissolve, and the removal of calcium ions should promote more calcium hydroxide going into solution.
Honestly I don't really know as it's all just speculation right now. But I do have both lithium carbonate and calcium hydroxide, so I think I'll give
it a try tomorrow and see how it goes.
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WGTR
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Hmmm...just throwing this out there; I haven't tried it myself...
How about mixing two ethanolic solutions of LiCl and NaOH? The NaCl would be insoluble, leaving the LiOH in solution. These are some solubility
figures that I came up with for ethanol:
LiCl: 5.77 mol/L
LiOH: 0.99 mol/L
NaOH: 3.5 mol/L
NaCl: 0.01 mol/L
As a bonus, here's a paper on the production and precipitation of Li2O2 from alcohol.
http://digitool.library.mcgill.ca/R/?func=dbin-jump-full&...
[Edited on 11-22-2015 by WGTR]
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papaya
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Hmm, LiNO3 route seems interesting, thank you, I didn't know that Li salt decomposes to Li2O instead of nitrite (like other alkalis), do you have any
information as how long should I heat it to go to completion ? Also, if I use gas burner to heat it put into SS cup for example, should I worry if it
reacts with combustion product CO2 to form again Li2CO3?
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CharlieA
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Robert Bruce Thompson of "Illustrated Guide to Home Chemistry Experiments" fame, , in his supplemental newsletter dated 30 October 2010, Made LiOH
from Li2CO3, and Ca(OH), in aqueous solution, using Li2CO3 obtained from a pottery supplier.
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Upsilon
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| Quote: Originally posted by papaya | | Hmm, LiNO3 route seems interesting, thank you, I didn't know that Li salt decomposes to Li2O instead of nitrite (like other alkalis), do you have any
information as how long should I heat it to go to completion ? Also, if I use gas burner to heat it put into SS cup for example, should I worry if it
reacts with combustion product CO2 to form again Li2CO3? |
Even nitrites will decompose into oxides at some temperature, so the result is the same regardless of whether or not there is a nitrite intermediate
step.
I have no idea how long you should heat it for. That would probably be something to experiment on. Titration would be very easy to determine the yield
of the decomposition since LiOH is a strong base.
Reaction with CO2 won't occur without some aqueous medium. Without water, first LiOH won't form. Second, no H2CO3 will form without water that would
be able to react with any LiOH. Solid LiOH left in air will slowly convert to Li2CO3 because LiOH is also very hygroscopic, absorbing enough water to
allow the reaction to occur.
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papaya
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I think alkali metal oxides can react with CO2 even in the total absence of water, how fast however is unknown. At least Me2O2 peroxides and MeO2
superoxides react with that and are/were used to recycle oxygen in places like submarines,space stations, etc.
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