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Synthisis Of Potassium Perchlorate


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#31 sasman

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Posted 02 December 2004 - 10:59 PM

Has anyone made any KCLO4 or NH4CLO4 ? here on the forum?....I would like further info on destroying the CLO3?....whats best to use Sulphite?,acid's?..This question was asked many moons ago..


Rob

#32 Pretty green flames

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Posted 03 February 2005 - 06:39 PM

http://www.logicsout...stuff/kclo4.txt


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I read that it can be adjusted to produce just chlorates. How would this be done
Any ideas anyone

#33 sasman

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Posted 03 February 2005 - 11:34 PM

I have seen this textfile somewhere else on the net..and would take its advice with a large pinch of salt :D ..From what i have read you "CANNOT" use carbon anodes to produce perchlorate..(It does work but very Very very ineffcient).

.The method he describes would work to produce Chlorate, but i cant see how it would produce Perchlorate at all..Using the sodium chloride / potassium chloride sounds good but what would actually happen?..

As soon as the chlorate forms it would start to precipitate potassium chlorate....Potassium chlorate solubility at 40 C is about 15g per 100grams water..The sodium chloride concentration is to high for perchlorate to form its easier for the cell to produce chlorate rather than perchlorate....so more chlorate would form which would precipitate out of solution..

I think this text file came from some crap jolly ro**r cook book crap...Also remember you must have a method of chemically destroying any residual chlorate..and then Testing the sample to make sure there is none left!..

I am a few weeks orso away from Medium Scale ClO3/ClO4 production using Both Platinium and Lead dioxide anodes..I am trying to perfect my lead Dioxide anodes..I have tried Electroplating 13mm Carbon Gouging rods but not had much success..The anodes must perform flawless for months at a time ..

So i have got some nice 10mm X 500mm Fine grained Graphite Anodes .(Altho if these dont work well ill go the Tantallium route) These will hopefully accept the lead dioxide coating better than the carbon rods..
. I am hoping to have a cell running at around 75 to 100 amps.

I've got all the chemicals for destroying and testing for chlorate..What i would like is that once i have made a large batch of ClO3,ClO4 i would like to have it tested by some laboratory?? to see how pure the product is ,but i dont know if that would be very expensive..

Edited by sasman, 15 March 2005 - 05:49 PM.


#34 Pretty green flames

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Posted 12 February 2005 - 08:20 AM

1 question.

I have 25 kg of Not so pure KCl (Around 80% pure) Will this effect the final product.

Please keep in mind that i am only making KCLO3 for a start.
The procedure is, that the KCl(aq) is electrolysed to yield KCLO3.

Edit: Can pure lead anode be used in place of PbO2 Anode.

Edited by Pretty green flames, 12 February 2005 - 02:26 PM.


#35 alany

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Posted 13 February 2005 - 02:32 PM

I finally got around to writing this up, I've been slowly rewriting my site's CMS:

http://www.vk2zay.net/article.php/63

More to come, thermal decomposition of Calcium Hypochlorite, Platinum/Iridium electrode test, microfiltration of anode mud, and a few other experences. I am still learning of course, much work to be done before I can make Perchlorates, but I am getting there.

#36 Pretty green flames

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Posted 13 February 2005 - 03:25 PM

This is nice.

Any Chromates or Dichromates in your solution to increase efficiency.

Correct me if i'm wrond but there was roughly 145grams of KCl dissolved in water to make 600ml of solution and you got 55grams of pure KCLO3 after purifications.
So you got a yield of 37.9%.

Would effiniency increase if you were to use a Titanium Anode and Stainless steel cathode.

Anyone have any idea +how many % would Chormates or Dichromates give.

Also how did you maintain the temperature at 65C(+/-5C)

Edited by Pretty green flames, 13 February 2005 - 03:29 PM.


#37 sasman

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Posted 13 February 2005 - 03:51 PM

Alany you mention that the solution started to wick up the graphite ?..Now My graphite anodes electrical connections are made via screwing threaded stainless steel rod into the graphite anode...

What distance would you recomend the electrical connection be from the surface of liquid??..
How high do you think the solution would wick up the graphite?...This is my only concern in making good anodes..I would rather make direct electrical connections to the graphite.. Rather than the lead dioxide which require slivered connections to avoid the over heating problems..

The test cell i tried used platiunium electrode mesh and i used silicon sealer to protect the connections but it still corroded.. i am thinking of using those small polystyrene balls(the one used to fill bean bags?) to float on the surface liquid to limit evoporation and reduce the corrosive spray..just not sure if the polystrene will dissolve in the solution..

#38 alany

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Posted 13 February 2005 - 05:58 PM

Any Chromates or Dichromates in your solution to increase efficiency.


Nope, just straight saturated KCl solution.

Correct me if i'm wrond but there was roughly 145grams of KCl dissolved in water to make 600ml of solution and you got 55grams of pure KCLO3 after purifications.
So you got a yield of 37.9%.


Remember that those 55 g were extracted from 1/2 of the electrolyte volume and the cell only ran for 1000 Ah before it went open circuit due to anode support structure corrosion.

I finally got the mud out of the other half of the electrolyte - the secret - two filter papers and lots of dilution so I could do it luke warm. I wasted about half (of the muddy half) trying to filter it through bran and rice husks, it picked up too many organics for my liking so I disposed of it. The remaining quarter is now crystal clear and probably has 25 g or so of chlorate in it. I think I'll just concentrate it and recycle it back into the next run.

Would effiniency increase if you were to use a Titanium Anode and Stainless steel cathode.


Perhaps, mainly from the better conductivity of the electrode substrate. The graphite isn't as good a conductor as Titanium and Steel and would waste less power in I^2R losses. I doubt the electrochemical efficiency would be much better unless I controlled the pH.

Also how did you maintain the temperature at 65C(+/-5C)


Passive cooling. That was the temperature it stabilized at. The PSU was delivering about 20 Watts to the cell, most of that ends up as heat. The cells geometry, enviroment and materials determine its thermal properties. I just had it sitting on the window sill in the kitchen for two weeks.

What distance would you recomend the electrical connection be from the surface of liquid??


Well mine were about 1" out of the solution before the lid, so a lot more than that is all I can really say.

The spray from the gas production is pretty fine and will float all over the place, you can't really stop it. I'd suggest Titanium for your anode connections, it will protect itself as long as you keep the voltage on it below about 10 V (its oxide breakdown voltage - Niobium goes to about 20 V which is why it is prefered for Perchlorate electrode substrates). If I had gouging rods for electrodes I'd run them right through the cell lid and seal both sides of the penetration with sealant, then make my connection to the graphite outside the cell in the dry. I just happened to have two commercial rectangular prism graphite electrodes with brass posts in them so I used them, rods would be easier to make water and gas tight seals with the lid.

I doubt the styrene will dissolve in the solution, but the wet chlorine may react with it. Not sure if that would steal chlorine from your cell or not. Not sure you'd need them as long as everything exposed to the spray is either bound to the cathode or is made of a Titanium or Platinum group metal.

#39 Pretty green flames

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Posted 14 February 2005 - 03:38 PM

May i ask

What was the full running time of your cell.

EDIT: Found a supplier for Titanium bars for EU and Worldwide
http://www.flexistep...anium_Bars.html

Edited by Pretty green flames, 14 February 2005 - 04:23 PM.


#40 alany

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Posted 14 February 2005 - 05:14 PM

What was the full running time of your cell.


335 hours, almost exactly two weeks near as I can figure, the cell was cold when I found it failed, so it may have been a day or so less worst case. Either way 1000 Ah is pretty close. If you do the math something is clearly wrong, maybe the current meter on my PSU was playing tricks on me:

One mole of electrons, or a Faraday, contains 6.0221415e23 electons(Avogadro's Number, /Na/) and a Coloumb is 6.241506e18 (one Ampere-Second) of electrons passing by. So a Faraday is 96485.4 Coloumbs or 26.8 Ampere-hours.

It takes 6 moles of electrons to make one mole of KClO3 at 100% efficiency. So you need 160.8 Ampere-hours to make one mole under ideal conditions. One mole of KClO3 weighs 122.549 g and one mole of KCl is 74.551 g/mol.

I had a starting saturation of around 400g/l as I never really allowed my saturated solution to cool right down and stabilise at room temperature. That means my cell had about 240 g or 3.3 moles of KCl to start with. If I had converted all of it I would have got a yield of almost 395 g of chlorate and it would have taken at least 530.64 Ah to do it.

At 55% efficiency 1000 Ah should have been roughly sufficient to convert everything in the cell. That might explain the heavy erosion of my electrodes, but it doesn't explain why I was only able to get 55 g of pure crystals out, I was probably too conservative with my recrystalisation efforts. There must be a lot left in the rest that's sitting in the jar outside.

Looks like I need to check the PSU meter calibration and redo the experiment more carefully. One thing I didn't consider until now is that the PSU might have been tripping out. It has thermal protection circuits, so it may not have been powering the cell all the time. It didn't really like operating in the cell load very much, so I guess all bets are off on the supply, I'll use a multimeter next time.

#41 Pretty green flames

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Posted 15 February 2005 - 07:48 AM

Hmm.....
just a thought

Instead of Using KCl and waiting a full 2 weeks for it to change to KCLO3, Why not use Regular salt (NaCl) and change it to NaClO3. After the electrolysis has ended purrify the product. Then make a boiling solution of NaClO3 and add 75g of KCl for every 58g of NaClO3 you have in the solution. KClO3 would just fall out of the solution.

This is also less time consuming

#42 alany

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Posted 15 February 2005 - 09:47 AM

This is also less time consuming


Not really. If all you want is KClO3 then starting with KCl is quite easy and expedient.

The KClO3 will crystalise out as you run the cell, so if your using "insoluable" electrodes all you need to do at the end of the run is just let it cool and wash the crystals to remove any KCl. You can recystalise it if you want to be really sure you've got pure KClO3.

However, if you want KClO4 then you need to start with NaCl because the solubility of KClO3 is too low to make a practical ClO4 cell with it.

The big advantage of making KClO3 directly from KCl is there is no Na in there at all. That makes it very clean for colour production. You don't need to purify and wash the product as carefully to get all the Na out.

The only disadvantage of making KClO3 directly from KCl I can see is if your electrodes aren't very good you'll need to filter the solution hot, which can be very tough on the filter paper. You can boil the solution first to convert the hypochlorite and hydroxide and then dilute it a bit to stop it crystalising out in the filter too much which helps. Then you might want to concentrate it a bit by boiling before letting it crystalise out.

If you filter the electrolyte straight out of the cell it will eat cheap filter paper, check out this unbleached coffee filter that was bleached by the hypochlorite out of a cell that ran for only an hour:

http://nexus.cable.n...ched-filter.jpg

#43 Pretty green flames

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Posted 15 February 2005 - 09:51 AM

I see

Anyway I'll try both methods and post the results.
But first i got to order some electrodes

#44 Old1953

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Posted 17 February 2005 - 04:23 AM

Has anyone tried tantalum as the cathode/anode material? It is used in some of the DSA type anodes.

The wire and other forms are readily available, either from suppliers (ouch) as surplus or by taking old capacitors apart.

#45 sasman

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Posted 17 February 2005 - 08:51 AM

Tantalium sounds like the next best thing to platinium but its still very expensive...If i cant get a decent coating of lead dioxide on these graphite rods i have ill try tantalium wire...if you read the Patents it makes a very good substrate for lead dioxide coating..




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