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Posts: 12
Registered: 6-5-2019
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Preparing Tetrasodium Pyrophosphate from Disodium Phosphate?
I am trying to replicate a procedure on generating a manganese phosphate coating for steel, and often the steel's surface is washed with a manganese
salt and sodium pyrophosphate. This step provides a much finer manganese phosphate coating later, which is more resistant to corrosion. However, I do
not have any tetrasodium pyrophosphate, and I'd rather not buy a couple hundred grams of something I only need a couple grams of.
It seems it would be easy enough to produce by first reacting phosphoric acid with sodium carbonate to yield disodium phosphate, which is then dried
and heated to around 450C.
I'm looking for some advice on how to heat this material to that temperature. I don't have a kiln, and haven't done anything that hot. I considered
maybe putting the powder (probably some 5-10g) in a small steel cup, covering with a steel coffee can, and placing it inside a charcoal grill. I could
use a blower or something if that's required. I've seen contradictory information on how hot charcoal is. Alternatively I could heat the vessel
directly with a propane torch.
Would a steel vessel be appropriate for this? I don't have one, but it wouldn't be too expensive to buy a small porcelain crucible.
I don't think there should be too much of a concern of decomposing the salt, considering it melts at 1000C.
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Bedlasky
International Hazard
Posts: 1239
Registered: 15-4-2019
Location: Period 5, group 6
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I did it in a stainless steel can without an issue.
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