making potassium (per) chlorate

[WSM]

In preparing to write part ten of my series on Homegrown Oxidizers, in which I turn raw sodium perchlorate into pyrotechnics grade potassium perchlorate, I'm studying the purification of the sodium perchlorate.

 

The first step is to destroy the residual chlorate. So far, the best method I've found follows Swede's technique using potassium metabisulfite as a sulfur dioxide source (sulfur dioxide breaks chlorate down to hypochlorite and chloride). Swede's method is for purifying his homemade potassium perchlorate and involves a lot of water and heating to get the less soluble potassium salts dissolved and reacted.

 

My understanding at this point is my sodium variation will be much simpler due to the highly soluble nature of most sodium salts. So the materials required are:

 

Raw sodium perchlorate solution

sodium metabisulfite solution

hydrochloric acid

sodium hydroxide solution

 

I'm hoping that by carefully preparing and using measured amounts of the last three items on the list, I can determine the starting concentration of the first list item.

 

My hope is that I'll be able to make chlorate-free sodium perchlorate from which I can make pure potassium perchlorate, which will immediately drop out of solution and be ready for vacuum filtration and pure water rinsing. After all this (and drying the final product) comes testing to prove (hopefully) the purity and quality of my final product.

 

I've looked forward to this experiment for a long time and I hope it'll turn out as expected.

 

WSM

Edited May 13, 2015 by WSM

[pex]

I cleaned up my sodium perchlorate only with sodium metabisulfite. Start with cold solution of perchlorate put in your sodium metabisulfite. And start heating. This will stink verry mush. Sow keep your distance and wat your ppm. After you solution starts to boil wait a few minutes. Take a smal sample and test it with indigo carmin. When there is still chlorate keft. Let it cool down. And do the same proses again. Till your testing chlorate free liquor. After this. You got perchlorate. With a.lot of metabisulfite in it. I first make a solution of kcl and put the two togetter. And let it stand a night over to Let it settle. The next day i Take out the kclo4 and rinse it with water. Just is long the smile of metabisulfite is gone. It's a verry easy proces but keep rinsing. Til you don't smell it annymore. It will Take a lot of water.

 

Pex

[WSM]

I cleaned up my sodium perchlorate only with sodium metabisulfite. Start with cold solution of perchlorate put in your sodium metabisulfite. And start heating. This will stink verry mush. Sow keep your distance and wat your ppm. After you solution starts to boil wait a few minutes. Take a smal sample and test it with indigo carmin. When there is still chlorate keft. Let it cool down. And do the same proses again. Till your testing chlorate free liquor. After this. You got perchlorate. With a.lot of metabisulfite in it. I first make a solution of kcl and put the two togetter. And let it stand a night over to Let it settle. The next day i Take out the kclo4 and rinse it with water. Just is long the smile of metabisulfite is gone. It's a verry easy proces but keep rinsing. Til you don't smell it annymore. It will Take a lot of water.

Pex

 

Hi Pex,

 

Thanks for sharing your technique for making potassium perchlorate from raw sodium perchlorate solution. It looks like it'll work for small batches, but I've thought it through and feel that for large batches or a continuous operation, controlling things by pH will be easier than boiling down large amounts of electrolyte.

 

I'm grateful for alternate suggestions. Even if it doesn't work for me, it may be just what someone else needs, and it's good to post it here.

 

WSM

[pex]

You don't have to boil it al down. Just heat it, and put your metabisulfite in the cold solution. After it starts to boil you can test it on left chlorate. It's a realy easy proses. I used it with 10 liters of elecrolite at once. And it workt fine for me 😊

 

Pex

Edited May 14, 2015 by pex

[THEONE]

If i had a chlorate free sodium perchlorate i should make some ammonium perchlorate.

[Arthur]

An important feature of the professional method will be limiting the amount of waste. It's most helpful if the finished liquor can be recycled into the chlorate cell without accumulating too many nasties.

[WSM]

If i had a chlorate free sodium perchlorate i should make some ammonium perchlorate.

 

I haven't seriously considered making ammonium perchlorate because I find the potassium salt much more useful. I believe the ammonium salt will be a lot more involved to process than the potassium salt (if trying to duplicate the commercial product).

 

WSM

Edited May 15, 2015 by WSM

[WSM]

An important feature of the professional method will be limiting the amount of waste. It's most helpful if the finished liquor can be recycled into the chlorate cell without accumulating too many nasties.

 

This is true.

 

From my few observations so far, it appears the LD anode does a better job of converting the sodium chlorate to sodium perchlorate. I suspect I may have very low amounts of chlorate contamination from that batch (which I hope to prove when I purify it), and the depleated liquor and wash water can be charged with sodium chloride and run in a sodium chlorate cell, as you've said. We'll see where all this takes us...

 

WSM

[WSM]

You don't have to boil it al down. Just heat it, and put your metabisulfite in the cold solution. After it starts to boil you can test it on left chlorate. It's a realy easy proses. I used it with 10 liters of elecrolite at once. And it workt fine for me

Pex

 

After I try the other method and see how it works, I may give your method a try. We'll see...

 

WSM

[WSM]

I've been giving thought to building a sodium chlorate cell, to produce feed stock for my sodium perchlorate experiments. I'm debating whether to use a large reservoir and circulate by pumping the liquor up to a reaction chamber, then overflow back to the reservoir. If it works the way i imagine it would, I could generate a huge amount of material for future experiments.

 

This is attractive because it's difficult to find sodium chlorate at an economical price in my area. Making sodium chlorate will be the next project after I make potassium perchlorate from my last runs.

 

WSM

[WSM]

I've been giving thought to building a sodium chlorate cell, to produce feed stock for my sodium perchlorate experiments. I'm debating whether to use a large reservoir and circulate by pumping the liquor up to a reaction chamber, then overflow back to the reservoir. If it works the way i imagine it would, I could generate a huge amount of material for future experiments.

This is attractive because it's difficult to find sodium chlorate at an economical price in my area. Making sodium chlorate will be the next project after I make potassium perchlorate from my last runs.

WSM

 

Has anyone here made sodium chlorate? Please share your experiences. Thanks.

 

WSM

[THEONE]

I have made some with homemade mno2 anode

[schroedinger]

I've done it. It's quite a bad job to do.

First you need to bring your cell up to i mean 600 g/L of Chlorate. Then you need to know how much chlorate is produced per hour. Add about 200 g / L of NaCl and run until you are down to about 100 g NaCl / L. Let your cell cool, so that the Chlorate can precipate out. Now run that cycle again.

[dangerousamateur]

Schroedinger, how pure was your NaClO3?

I found it impossible to produce pure enough, because it's solubility is the same like the chloride.

[WSM]

You don't have to boil it al down. Just heat it, and put your metabisulfite in the cold solution. After it starts to boil you can test it on left chlorate. It's a realy easy proses. I used it with 10 liters of elecrolite at once. And it workt fine for me

Pex

 

The method you describe (heating the solution with metabisulfite) would leave a lot of sodium sulfite in the solution.

Na₂S₂O₅ → Na₂SO₃ + SO₂

 

The method I'm considering (treating with HCl acid and metabisulfite) would yield sulfur dioxide, sodium chloride and water.

Na₂S₂O₅ + 2 HCl → 2 NaCl + H₂O + 2 SO₂

 

The answer is found in wikipedia under the heading of Sodium Metabisulfite.

 

WSM

[Arthur]

Which is important to get the waste tailings fit for recycling back to the chlorate cell.

 

Anyone with enough space to play chlorate production needs to consider where the effluent will go.

[WSM]

Which is important to get the waste tailings fit for recycling back to the chlorate cell.

Anyone with enough space to play chlorate production needs to consider where the effluent will go.

 

I think a few recyclings could be managed before the system would require heavy duty purging. I haven't studied the process well enough yet, to determine if there are simple methods of purifying the liquor of unwanted side products, allowing continual recycling of the mother liquor.

 

There is so much more to learn. Thanks to all who've posted links to useful electrochemical articles.

 

WSM

Edited May 17, 2015 by WSM

[WSM]

I think a few recyclings could be managed before the system would require heavy duty purging. I haven't studied the process well enough yet, to determine if there are simple methods of purifying the liquor of unwanted side products, allowing continual recycling of the mother liquor. There is so much more to learn. Thanks to all who've posted links to useful electrochemical articles.

WSM

 

To acidify and neutralize the raw sodium perchlorate, I made up a liter each of 3M HCl and 3M NaOH. I've also made up some sodium metabisulfite (Na₂S₂O₅) solution.

 

My plan is to:

 

1) acidify small samples of the perchlorate liquor to pH 3.0 with HCl

2) alternately apply small, measured doses of metabisulfite and test for chlorate till it tests negative

3) neutralize the acid with NaOH till it approaches pH 7.0

4) add measured doses of KCl till no more potassium perchlorate drops out of solution

5) vacuum filter the potassium perchlorate followed by rinsing with chilled distilled water

6) dry the potassium perchlorate and test for purity

 

I'll do this with samples of the raw sodium perchlorate from both test cells and observe and record the differences and similarities I see. The results of these efforts will be posted here plus be featured in part ten of my series on Homegrown Oxidizers in the PGI Bulletin.

 

The next effort will be trying to make pure sodium chlorate to use as feed stock for the perchlorate cells and recording the results (and the differences from reagent grade sodium chlorate used for the first runs of the two perchlorate cells).

 

WSM

Edited May 23, 2015 by WSM

[THEONE]

How you can purify NACLO3 to use it into perchlorate cell, and then purify NACLO4 for making NH4CLO4 ?

[WSM]

How you can purify NACLO3 to use it into perchlorate cell, and then purify NACLO4 for making NH4CLO4 ?

 

I haven't worked out purification processes for sodium chlorate (NaClO₃) yet, but it's on my "to do" list.

 

Items one through three of my "plan" above would seem to be a good start to making ammonium perchlorate. Be absolutely certain all chlorate is destroyed before any ammonium compound is added to the perchlorate mixture (any amount of ammonium chlorate present would make a bad day!).

 

WSM

Edited May 24, 2015 by WSM

[WSM]

I have made some with homemade mno2 anode

 

How did things go with your MnO₂ anode? Have you ever tried MMO, and if so, how do they compare?

 

WSM

[WSM]

 

The method I'm considering (treating with HCl acid and metabisulfite) would yield sulfur dioxide, sodium chloride and water.

Na₂S₂O₅ + 2 HCl → 2 NaCl + H₂O + 2 SO₂

 

(3SO₂+ 3H₂O → 3H₂SO₃

3H₂SO₃+ ClO₃^- → Cl^- + 3H₂SO₄)

 

One problem with re-using the filtrate and wash water after the potassium perchlorate has been filtered out is there'll be considerable sodium sulfate (Na₂SO₄) residue left over from the metabisulfite treatment of the raw sodium perchlorate solution.

 

3Na₂S₂O₅ + 3H₂O + 2NaClO₃ → 3Na₂SO₄ + 3H₂SO₄ + 2NaCl

 

Next treating the solution with sodium hydroxide to neutralize the acid produced:

 

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O and even more sodium sulfate is produced...

 

To remove all that sodium sulfate, I first considered using calcium hypochlorite which would drop out the sulfate as calcium sulfate and create sodium hypochlorite in the process (if it would work without further dissociation into chlorine gas , etc.). When I researched further, two problems appeared; 1) calcium hypochlorite isn't highly soluble, and 2) it's often mixed with other (undesireable) chemicals. Plus, even at best, the product of commerce (calcium hypochlorite) is not very pure.

 

It occurred to me, the solution to this problem is to use instead, calcium chloride (CaCl₂) sold in hardware stores as "Damp Rid".

 

Na₂SO₄ + CaCl₂→ CaSO₄↓ + 2NaCl

 

Calcium chloride is highly soluble and comes in fairly high purity, plus is widely available at a reasonable cost.

 

By this means I believe the sulfates produced by the destruction of chlorate in the raw sodium perchlorate solution, can be removed from the depleted liquor and wash water by filtration, before recharging the filtrate with more NaCl and using it in the sodium chlorate cell. This makes recycling the depleted sodium perchlorate liquor possible and eliminates a lot of waste.

 

WSM

Edited May 25, 2015 by WSM

[THEONE]

 

How did things go with your MnO₂ anode? Have you ever tried MMO, and if so, how do they compare?

 

WSM

I have never work with MMO. I am quite satisfied with Mno2 electrodes. They are good chlorate makers with almost no errosion. They can easily be made and heal them too. They can also be made from cheap and easily available materials. Edited May 25, 2015 by THEONE

[THEONE]

One idea. Is it possible that hydrated titanium (TiH2) produce chlorates or perc ?

 

Also hydrated titanium will oxidize with time to Ti oxide, like Ti metal does ?

Edited May 25, 2015 by THEONE

[WSM]

One idea. Is it possible that hydrated titanium (TiH2) produce chlorates or perc ?

Also hydrated titanium will oxidize with time to Ti oxide, like Ti metal does ?

 

I don't believe so. I don't think TiH₂ or TiO₂ alone are conductive enough to useful as an electrode. When mixed or blended with RuO₂ and/or IrO₂, MMO is formed and is conductive enough to make a good chlorate anode.

 

Try a Google search of the individual materials and see what I mean...

 

WSM