Are you sure you can use carbon rods for the ClO3- -> ClO4- cell? I know you can for Cl- -> ClO3 .... but I was under the impression that the current required is too high for carbon electrodes and would errode too quickly? I dont know I'll have to look later.

 

I have notion that it would still have amounts of KClO3.... Aspirin, again what is your contamination roughly? Is it like half and half? Or is there trace amounts you're trying to get rid of? This changes your approach. If there are large quantities of KClO3 one could approach it with an electrochemical cell; if they're trace, one would probally further clean it up with solubility differences. Check the numbers I put on the first page... you'll probally need to find more numbers for KClO4 (if worst comes to worst you can find them yourself empirically?). Example of how I'd approach this.... If there was a 10% contamination - for a 100 gram sample you put it in a bit more boiling water than what is required for dissolving 10 grams of KClO3 at ... say 10oC. Bring the temperature down and a lot of precipitate will come out... majority KClO3. You're losing some KClO4 in the process since it stays suspended with the KClO3.... just less of it. In fact ... do the math, you might find that between the two piles of powder you make one is quite pure KClO4 and the other is fairly pure KClO3? You might have to look into the temperatures some for optimization.

 

EDIT:

Here's a good resource for what YT was talking about.

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/chlorate.html It also has some good solubility charts comparing the different salts.

you need not translate my answers. you appear to be ineffective in doing so

Carbon rods will indeed work perfectly well.

and current isn`t really the issue, it`s maintaining the correct voltage that counts, having suficient current in reserve to maintain this. but on a small scale (non industrial) it`s not a significant issue

 

the key to this more than else is the ability to WAIT patiently

Guys. If you do electrolysis of NaCL under 40 Celsius' degrees, you will create sodium hypochlorate(NaCLO). If you do it over 40 Celsius' degrees, you will create sodium chlorate(NaCLO3). I want to answer something. Can anybody give the perfect voltafe and the type of electrodes to make this electrolysis?

Add 20% concentrated hydrochloric acid. It will reduce all the chlorate to chloride, giving off chlorine gas, while leaving the perchlorate alone.

 

KClO3 + (6)HCl --> KCl + (3)H2O + (3)Cl2

 

Despite having one more oxygen atom, perchloric acid, at least under 70% concentrated, is suprisingly inert from an oxidative point of view. It will not even be reduced by its reaction with zinc metal, whereas nitric acid is.