dann2
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Sodium Persulphate from Ammonium Persulphate
Hello,
Have Ammonium Persulphate. Want Sodium Persulphate.
Can I make the Na Persulphate by adding Sodium Carbonate to the Ammonium Persulphate (in water) and boiling untill all Ammonia and CO2 are gone?
TIA,
Dann2
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len1
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I for one cant see why not. Still better is to use NaOH as its more readily available and the pH is 2-3 higher - which means the ammonium impurity in
the final product will be 2-3 orders of magnitude lower. Persulphate decomposes around 150C I think (giving O2) but it can definitely stand up to
100C as I use it in PCB baths
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garage chemist
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No, you can't boil persulfate solutions, they'll decompose into oxygen.
You need to use NaOH instead of Na2CO3. React stochiometric amounts of NaOH and ammonium persulfate in a small amount of water under cooling, expell
the ammonia by bubbling in air and dry out the solution in a warm place, or preferrably in a desiccator.
That's the way industry makes sodium persulfate, they have to make ammonium persulfate first because its solubility is low enough to allow
crystallization from the electrolyte by cooling.
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len1
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| Quote: | Originally posted by garage chemist
No, you can't boil persulfate solutions, they'll decompose into oxygen. |
I regularly use persulphate for etching PCBs and I have never seen anything but a few bubbles evolved if you get the temperature near boiling. These
solutions are pretty concentrated so there would be huge frothing if anything like a stoichiometric amount of oxygen were to be evolved. So my
question is, are you sure about this?
The second option is boil the water away under 12mm - that will surely work.
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garage chemist
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I've worked with persulfate as well, and got a strong smell of ozone when heating its solutions to boiling.
Also, the NaOH might further catalyze the decomposition.
Yes, vacuum would be very good for removing both the ammonia and water in one step.
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dann2
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Hello,
Thanks for replys. I do not need to isolate the solid. The Na Persulphate in solution will do fine.
Cheers,
Dann2
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