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?Gammatron - 9-9-2022 at 14:58
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.Rainwater - 9-9-2022 at 18:23
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 problemskaaskonijn - 10-9-2022 at 04:34
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? Rainwater - 10-9-2022 at 15:13
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
I am going to use the NaOH to make sodium silicate as a refractroy cement
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
