woelen
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How strong is the effect of sodium ions really?
I purchased a PbO2 anode and intend to make NaClO4 with these, by electrolysing a solution of NaClO3 (which I in turn make by electrolysing a solution
of NaCl with MMO). Making KClO4 from KCl directly is no option, because of the low solubility of KClO4 (it would clog the PbO2-anode and possibly lead
to mechanical strain on it, which may damage it).
So, I make NaClO4 and then by adding KCl to this, I let KClO4 precipitate and will make this more pure by recrystallizing from water. In the past I
have done that, and I obtained really snow-white products from a yellow solution, containing chromate and dichromate. But based on color, of course, I
cannot see how much sodium is still left in the product.
I want to use the KClO4 for color flame demos. I know that the presence of even small amounts of Na-ions in the mix spoils the flame colors of other
metals. By now I want to have more precise insight. What is "a small amount"? If I e.g. have 0.5% Na(+) ions and 99.5% K(+) ions in the final product,
how bad is that? Even the KCl, which I have is not really pure. According to its specification, it contains at most 0.7% NaCl and it is free of
detectable amounts of transition metals and calcium and magnesium. So, I am quite sure I will end up with a product, which will contain a few tenths
of percents of sodium ions.
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woelen
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Another option I have is making KClO3 from KCl, using MMO electrodes (I have done that in the past). But my KCl contains at most 0.7% NaCl.
I can buy KCl (99.9+ %), but that stuff is expensive. I do not want to spend much money on KCl. What if I use the KCl with the 0.7% NaCl? Can I remove
the Na(+) ions sufficiently in the final product, so that I do not have issues with flame color?
This KClO3-alternative, however, is not my favorite option, because of the higher risk of playing with KClO3 in flame mixes, so the option described
in the previous post is something I like more.
I have very little experience with flame colors and compositions for that, I assume that more pyrotechnics-oriented people can tell more about this
from personal experience and that I do not have to find out all of this with great experimental effort (keep in mind that I have no source of KClO3 or
KClO4 by simply buying it, I have to go through the quite laborious way of electrolysing and working up the impure product from that, making a few
tens of grams for these experiments).
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teodor
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Probably you can precipitate the traces of sodium by the pyroantimonate ion ([Sb(OH)6]-). The sodium salt is quite insoluble and potassium is soluble.
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clearly_not_atara
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This seems like a question for the "just try it" bucket. If you recrystallize it twice and you still don't get the right flame color, then you can get
creative.
[Edited on 04-20-1969 by clearly_not_atara]
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Dr.Bob
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There are a lot of people in the energetics group that make KClO4, so that may be the place to ask. The pyros know their perchlorates. But I think
0.5% Na may be too much for a clean color other than yellow.
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woelen
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Thread Moved
11-1-2024 at 06:27 |
woelen
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As suggested by Dr.Bob, moved thread to energetic materials section.
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