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Author: Subject: Sulfuric acid from gypsum using diaphragm cell
Fulmen
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[*] posted on 12-10-2018 at 08:40


OK, I now have 4 samples ranging from 60 to 100mg/cm^2 of PVA/borate. It's probably far thicker than it needs to be, so I'll prepare a couple of tests using wet-strong paper towel.



We're not banging rocks together here. We know how to put a man back together.
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Jackson
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[*] posted on 12-10-2018 at 08:41


Is it PVA glue?

Is the membrane better or worse than a clay flowerpot?

[Edited on 10/12/2018 by Jackson]
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madcedar
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[*] posted on 12-10-2018 at 15:12


Yes it's PVA glue that he is talking about, the white stuff everyone uses at home. It can be set with a 4% solution of borax in water.
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mysteriusbhoice
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[*] posted on 16-10-2018 at 00:02


From production of sulfuric acid to creating homemade IEM one thing does lead to another after all
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mysteriusbhoice
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[*] posted on 20-11-2018 at 09:59


Guys update to this project:
if you add a 3rd small compartment where the cathode goes with holes at the bottom where the alkaline liquid will collect then you can discard it every 12 hours after which you keep adding more Na2SO4 into it to continiously drop the PH on the anode side until you have a fairly concentrated solution of H2SO4.
and to get Na2SO4 you could start with CaSO4 and react it with NaOH on the stove and the liquid obtained can be used as the new electrolyte but keeping the CaSO4 slurry barrier around the paper will help improve collection.

also I am currently producing HCl using this method by adding only some sulfate ions in the initial run and instead of filling Na2SO4 into the cathode compartment after flusing out the NaOH produced I fill it with NaCl which reacts with the H2SO4 on the anode side to produce HCl.

Where I live even HCl is restricted so I have to come up with these crazy solutions to produce them.
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MrHomeScientist
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[*] posted on 21-11-2018 at 12:17


I'm quite surprised this works. How is sulfuric acid made, when calcium sulfate is so insoluble? It seems unlikely that CaSO4 would be attacked by aqueous NaOH. Are you sure you aren't just electrolyzing the sodium sulfate you started with?
Is it required that you start with hydroxide solution in the inner container and acid in the outer container?
If this does indeed make sulfuric acid straight from gypsum, that's very cool and tremendously useful since gypsum is so common.
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Swinfi2
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[*] posted on 21-11-2018 at 12:52


When i did this with CaSO4 i did notice the solution started to cloud where it came into contact with the air but it wasn't so easy to tell if it had gone to completion as one whiteish powder looks a lot like another. I switched over to converting MgSO4 into Na2SO4 with NaOH in a seperate step.
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mysteriusbhoice
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[*] posted on 21-11-2018 at 21:57


Quote: Originally posted by MrHomeScientist  
I'm quite surprised this works. How is sulfuric acid made, when calcium sulfate is so insoluble? It seems unlikely that CaSO4 would be attacked by aqueous NaOH. Are you sure you aren't just electrolyzing the sodium sulfate you started with?
Is it required that you start with hydroxide solution in the inner container and acid in the outer container?
If this does indeed make sulfuric acid straight from gypsum, that's very cool and tremendously useful since gypsum is so common.

At high temperature it reacts with the NaOH accumulating in the cathode compartment and I made my Na2SO4 by reacting NaOH in a cooking pot with gypsum so the NaOH in the cell attacks more CaSO4 eventually producing Ca(OH)2
This video below shows that you can make Na2SO4 from a hot solution of NaOH
https://m.youtube.com/watch?v=_R9atKBUS8M
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mysteriusbhoice
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[*] posted on 21-11-2018 at 22:02


Quote: Originally posted by Swinfi2  
When i did this with CaSO4 i did notice the solution started to cloud where it came into contact with the air but it wasn't so easy to tell if it had gone to completion as one whiteish powder looks a lot like another. I switched over to converting MgSO4 into Na2SO4 with NaOH in a seperate step.

I have a new cell design that is for totally liquid reactants using Na2SO4 and no CaSO4 needed.
This cell has a cathode compartment filled with liquid and uses a porous barrier made from sand and the cathode is drained every 12 hours after the NaOH accumulates then the cathode liquor is frozen to precipitate Na2SO4 and the precipitate is put into the anode compartment to be recycled.
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mysteriusbhoice
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[*] posted on 21-11-2018 at 22:08


As for making IEMs out of PVA glue it works but I cannot use paper to hold the polymer.
I will try those really usable fiber bags next
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