onurtosun - 20-3-2018 at 00:07
Hello everyone,
I have a solution of potassium carbonate and sodium chloride. Is it possible to seperate them with analytical methods?
Note 1: Lots of ethanol can be used according to the diffirent solubilities of these salts in ethanol but propesed way must be applied to the
industry scale so I' m not sure that will be economical.
Note 2: An evaporation can be performed at the beginning of the seperation. K2CO3 and NaCl can be obtained by solid-solid phase. Would that
benefit to make the seperation easier?
Thanks in advence for your helps.
RawWork - 20-3-2018 at 05:00
I can't tell you exactly what to do, because you didn't tell exactly what you have, how much, etc. So theoretically:
- use parameter which has biggest difference between these two compounds or these two elements if you only want to separate Na from K, regardless of
anions, for example their chlorides or elemental form has enough difference so it can be distilled normally, perhaps using lower pressure to avoid
high temp.
- when working with solutions (organic or aqueous) always some compound will precipitate first, so you can precipitate it in small amounts and test
each amount for purity, until you start detecting that another compound started to contaminate the precipitate, if purity is important for you, more
than yield or mass
I will demonstrate this for all elements and compounds when I become successful enough, hopefully soon.
AJKOER - 21-3-2018 at 16:53
Careful, this experiment may be more complex that one would expect.
First, note:
K2CO3 + 2 NaCl = Na2CO3 + 2 KCl
Next, there is at least one study of the molten salt structure of NaCl-Na2CO3 and the KCl-K2CO3 systems, see https://www.jim.or.jp/journal/e/pdf3/48/05/1034.pdf . So, I would not be surprised if related water based mixed salts also exist. For example, see
"Liquid-solid equilibrium for the NaCl-NaHCO3-Na2CO3-H2O system at 45°C. Validation of mixed solvent electrolyte model" at https://link.springer.com/article/10.2478%2Fs11696-013-0364-... . Also, see Sytniewski, A. (1998), "Regression analysis of the salts solubility of
the NaCl — NaHCO3 — H2O,.."
Another example is Northupite, Na2CO3.MgCO3.NaCl, which occurs naturally as a mineral, which can be prepared artificially by heating sodium chloride,
sodium carbonate, magnesium chloride, and water in a closed flask for eight hours at 100° C (see http://magnesium.atomistry.com/northupite.html ).
[Edited on 22-3-2018 by AJKOER]
Melgar - 21-3-2018 at 20:09
You're going to get sodium carbonate as the first thing to precipitate out from water. It has the lowest solubility by quite a lot.
I take it you're not trying to reclaim NaCl, because that's so cheap there's no point, so I'm assuming you're trying to reclaim K2CO3. If that's the
case, you might want to consider a small-scale implementation of the Solvay process. That'd give you sodium and potassium carbonate salts, which
would be far easier to separate via their solubilities:
https://en.wikipedia.org/wiki/Solvay_process
onurtosun - 21-12-2018 at 03:04
Thanks for all answers. Actually, I want to purify technical grade carboxymethyl cellulose (~%70 active matter content) with 70% ethyl alcohol. In
this process the by-products of sodium chloride and sodium glycolate(which are belong to etherification reaction while manufacturing of sodium
carboxymethyl celluolose (NaCMC)) are dissolved in 70% ethyl alcohol and >95% purified NaCMC can be obtained. Because of the high costs of
distillation, I tried to use salt out technique with potassium carbonate to enrichment of ethyl alcohol to the desired percantage. Everything works
great but if i could seperate these salts from each other, I can use the potassium carbonate for several times in this process.
Thanks in advence for your answers.
AJKOER - 23-12-2018 at 17:56
Per this source https://www.researchgate.net/publication/231541490_Phase_Equ... , to quote:
"potassium and sodium carbonate double salt (K2CO3·Na2CO3·12H2O)"
where the Na2CO3 could form via:
K2CO3 + 2 NaCl = Na2CO3 + 2 KCl