Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Synthesis of KOH
MrFormula
Harmless
*




Posts: 11
Registered: 2-10-2023
Member Is Offline


[*] posted on 29-4-2024 at 07:07
Synthesis of KOH


I am going to try to make activated charcoal and I found a patent numbered EP2982649B1 that has a manageable way of making it. However, I do need KOH to do it and have like 5lb of KCl so I was thinking I could do a double displacement with NaOH and KCl. From here though I am not sure how to separate the KOH, NaCl, and any leftover reactants. Any help would be much appreciated.

Just as a note I am fully aware that you can use electrolysis to make KOH but I really don't want to do this as I don't really have the equipment for it.

[Edited on 4-29-24 by MrFormula]
View user's profile View All Posts By User
fx-991ex
Hazard to Self
**




Posts: 86
Registered: 20-5-2023
Member Is Offline


[*] posted on 29-4-2024 at 08:10


both KCl and NaCl solubility are round 36g/100ml, KOH is slighly more soluble than NaOH. Double displacement wont be possible.

Also i tried to recrystalize KOH from a sln before and it etched the inside of the beaker and never crystallized, its extremely hygroscopic.
View user's profile View All Posts By User
Texium
Administrator
Thread Moved
29-4-2024 at 08:31
bnull
Hazard to Others
***




Posts: 276
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Offline

Mood: Sleepy (again)

[*] posted on 29-4-2024 at 08:59


Why not use NaOH? It is described in the patent.

How much KOH do you need?




Quod scripsi, scripsi.

B. N. Ull

P.S.: Did you know that we have a Library?
View user's profile View All Posts By User
MrFormula
Harmless
*




Posts: 11
Registered: 2-10-2023
Member Is Offline


[*] posted on 29-4-2024 at 09:10


Quote: Originally posted by bnull  
Why not use NaOH? It is described in the patent.

I want to follow experiment one as closely as possible to get the best results. I am making the activated charcoal for use in a homemade respirator. As of right now I do not intend actually use the respirator as ppe but I thought I would be fun to make my own filter cartridges.
View user's profile View All Posts By User
bnull
Hazard to Others
***




Posts: 276
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Offline

Mood: Sleepy (again)

[*] posted on 30-4-2024 at 05:12


Depending on the mass of KOH you need, you may try a double displacement with isopropanol as solvent. KOH is soluble in isopropanol, the other salts not so much. Just add NaOH and an excess of KCl to some tens of milliliters of isopropanol in a polypropylene bottle. Shake the mixture and then let it stand for some time (I don't know how long it will take; 20 minutes might be enough). Decant or filter the solids and boil off the isopropanol. Use a polypropylene bottle immersed in a water bath and connected to a condenser to crystallise the KOH and recover the alcohol.

[Edited on 30-4-2024 by bnull]




Quod scripsi, scripsi.

B. N. Ull

P.S.: Did you know that we have a Library?
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 2722
Registered: 3-11-2013
Member Is Offline

Mood: Big

[*] posted on 30-4-2024 at 06:10


You can get a very easy displacement as Ca(OH)2 + K2CO3 >> CaCO3 (s) + 2 KOH

And if lime is not available, then the displacement 2 NaOH + CaCl2 >> Ca(OH)2 (s) + 2 NaCl is also very simple.

I have my doubts about the displacement in isopropanol but it might work. The displacement of NaOH + KCl in water will definitely not work.




Quote: Originally posted by bnull  
you can always buy new equipment but can't buy new fingers.
View user's profile View All Posts By User
Texium
Administrator
********




Posts: 4544
Registered: 11-1-2014
Location: Salt Lake City
Member Is Offline

Mood: PhD candidate!

[*] posted on 30-4-2024 at 06:22


I know people don’t like to hear this, but… just buy it. Alkali hydroxides are not practical to make for the amateur. Yet, they are very cheap and readily available. Life’s too short to muck about with trying to make KOH.



Come check out the Official Sciencemadness Wiki
They're not really active right now, but here's my YouTube channel and my blog.
View user's profile Visit user's homepage View All Posts By User
fx-991ex
Hazard to Self
**




Posts: 86
Registered: 20-5-2023
Member Is Offline


[*] posted on 30-4-2024 at 08:06


Quote: Originally posted by bnull  
Depending on the mass of KOH you need, you may try a double displacement with isopropanol as solvent. KOH is soluble in isopropanol, the other salts not so much. Just add NaOH and an excess of KCl to some tens of milliliters of isopropanol in a polypropylene bottle. Shake the mixture and then let it stand for some time (I don't know how long it will take; 20 minutes might be enough). Decant or filter the solids and boil off the isopropanol. Use a polypropylene bottle immersed in a water bath and connected to a condenser to crystallise the KOH and recover the alcohol.

[Edited on 30-4-2024 by bnull]

I dont have solubility data for this but it may work only if NaOH and KCl is more soluble than NaCl in this solvent(isopropanol).(usually salt isnt very soluble in alcohol)

If not, your reactant NaOH/KCl will just crash out and nothing will happen.


[Edited on 30-4-2024 by fx-991ex]
View user's profile View All Posts By User
RU_KLO
Hazard to Others
***




Posts: 174
Registered: 12-10-2022
Location: Argentina
Member Is Offline


[*] posted on 30-4-2024 at 09:15


Quote: Originally posted by MrFormula  
I am going to try to make activated charcoal and I found a patent numbered EP2982649B1 that has a manageable way of making it. However, I do need KOH to do it and have like 5lb of KCl so I was thinking I could do a double displacement with NaOH and KCl. From here though I am not sure how to separate the KOH, NaCl, and any leftover reactants. Any help would be much appreciated.

Just as a note I am fully aware that you can use electrolysis to make KOH but I really don't want to do this as I don't really have the equipment for it.

[Edited on 4-29-24 by MrFormula]


Check Codi's video on acticated charcoal. I did not read the patent, its in german, but it seems that the correct process is to use superheated H2O vapor. Any other method using chemicals will not work.

https://www.youtube.com/watch?v=GNKeps6pIao&ab_channel=C...
https://www.youtube.com/watch?v=S5Ac8PIfBdY&ab_channel=C...




Go SAFE, because stupidity and bad Luck exist.
View user's profile View All Posts By User
bnull
Hazard to Others
***




Posts: 276
Registered: 15-1-2024
Location: Between the Atlantic and the Pacific Ocean
Member Is Offline

Mood: Sleepy (again)

[*] posted on 30-4-2024 at 09:26


Quote: Originally posted by fx-991ex  
I dont have solubility data for this but it may work only if NaOH and KCl is more soluble than NaCl in this solvent(isopropanol).(usually salt isnt very soluble in alcohol)

After searching futilely, it becomes apparent I don't have the data either because it is lost among the 2000 plus papers in the HD that I never bothered to rename. Crap.

@MrFormula: Oh, well. If you had potassium carbonate it would be trivial. My process may work but the odds are it'll be too slow with a crappy yield. You don't have equipment for electrolysis. There are two options: either you buy KOH or you exchange some of your KCl with a fellow chemist for KOH.

@RU_KLO: Here's the English version (I can barely read German): https://patents.google.com/patent/EP2982649B1/en

[Edited on 30-4-2024 by bnull]




Quod scripsi, scripsi.

B. N. Ull

P.S.: Did you know that we have a Library?
View user's profile View All Posts By User
Precipitates
Hazard to Self
**




Posts: 66
Registered: 4-12-2023
Location: SE Asia
Member Is Offline


[*] posted on 30-4-2024 at 18:38


Quote: Originally posted by fx-991ex  

I dont have solubility data for this but it may work only if NaOH and KCl is more soluble than NaCl in this solvent(isopropanol).(usually salt isnt very soluble in alcohol)

If not, your reactant NaOH/KCl will just crash out and nothing will happen.

[Edited on 30-4-2024 by fx-991ex]


KCl is practically insoluble in IPA.

Perhaps dissolve the reactants in water first and then crash out with alcohol - although I really have my doubts with this technique. It's just not that easy to produce KOH.
View user's profile View All Posts By User
MrFormula
Harmless
*




Posts: 11
Registered: 2-10-2023
Member Is Offline


[*] posted on 1-5-2024 at 04:02


Quote: Originally posted by RU_KLO  


Check Codi's video on acticated charcoal. I did not read the patent, its in german, but it seems that the correct process is to use superheated H2O vapor. Any other method using chemicals will not work.

https://www.youtube.com/watch?v=GNKeps6pIao&ab_channel=C...
https://www.youtube.com/watch?v=S5Ac8PIfBdY&ab_channel=C...


I have seen both of the videos but this method is slightly different from anything he tested. There are two methods to making activated carbon, chemical and physical. For physical you use super heated steam or oxygen. For chemical the method describe is creating a melt with the KOH and carbon(carbon remains solid). This requires substantially lower temperatures.
View user's profile View All Posts By User

  Go To Top