kaaskonijn
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Platinum coated electrode in alkaline solution
I am wanting to make sodium hydroxide at home by membrane electrolysis (I know it is way cheaper and easier to just buy it). I got the membrane and
cathode working well, but I still need an anode that doesn't degrade. I was thinking of buying a MMO electrode, but they are hard to get and I really
don't want anything to do with things like lead oxides. So I have been looking at platinum coated anodes, but I have seen some datasheets of
professional platinum electrodes that they should not be used in electrolytes with a PH of higher than 12. But I can find almost noting about why it
would degrade them. Does anyone know if there could be problems with using a platinum coated electrode in a strongly alkaline solution, or is there
little to worry about? And does anyone know of any trustworthy sellers of platinum coated electrodes in Europe?
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Gammatron
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There are lots of MMO electrodes on eBay and Ali Express. I've purchased 3 from eBay relatively cheap and had no problem using them in a chlorate
cell. There is a seller on eBay in Germany if that makes shipping any easier for you.
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Rainwater
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I wouldn't think it would be a problem.
Just tested the ph in my setup, the cathode is +12 and the anode is between 8~9. The anode looks good and has been running for over 60 days.
I use a pt anode in a membrane cell to make NaOH from NaHCO3. Lead built up a crust I had to physically remove once a week. And I didn't want to deal
with Cl2 gas
Been running for a few months with no problems
"You can't do that" - challenge accepted
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kaaskonijn
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Rainwater, good to hear that it is possible with platinum electrodes. What do you mean by lead building up a crust? And do you know where you bought
your platinum electrode?
Gammatron, do you know how much of the oxides erode off? I am going to use the NaOH to make sodium silicate as a refractroy cement and I don't want
the hassle of having (little amounts of) toxic metal compounts in my furnaces. Do you know if it is something to worry about or not?
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Rainwater
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Best I could tell it was either lead carbonate or baking soda buildup, maybe a mix of both
Tested with hcl and it releases co2. Heat a sample it, it outgases and turns brown/black.
I got mine off amazon. 3 tries before I got a legitimate one.
Let me dig up a link..
Tested with magnet, h2o2. Basically followed nerdrage's instructions.
TWL PLANODE2X3 Platinized Titanium Anode 2"x3" https://a.co/d/b6LkwUH
Ive got 6 from this seller. No issues. But that was early 2021
Edit:
Ditto, I boil the NaOH solution down to about 40% salt by weight then use a modified pressure cooker. 50psi 250~300c for about 4 hours. Use the pot in
a pot method or your pressure chamber will get attacked.
I tried direct heating without pressure, with very poor results.
Know the dangers, take precautions.
Good luck and be safe.
Hot NaOH is dangerous at any scale
[Edited on 11-9-2022 by Rainwater]
"You can't do that" - challenge accepted
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Mateo_swe
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Be aware that there are very much fake platinum anodes for sale online.
If the price is low and it seems almost too good to be true, its fake.
Check for sellers with good comments on previous sold anodes.
I bought a nice Platinum Mesh Anode & Titanium Mesh Cathode Set from a seller called "gallium_guy" on ebay.
I also bought a MMO set from him and both the Platinum and MMO anodes are the real stuff.
I previously bought a Platinum Mesh Anode on ebay from china and its fake and unusable.
All those cheap platinum anodes from china is fake, all of them.
Good luck
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Texium
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Thread Moved
14-9-2023 at 12:02 |
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