Sciencemadness Discussion Board - Sodium perchlorate synthesis issues

Sodium perchlorate synthesis issues

ManyInterests - 18-10-2025 at 19:17

I know what you're thinking: Didn't you use the search option? Well I did, and I didn't find what I was looking for, so I decided to make a thread about the matter.

My first foray into chemistry was making chlorates, I wasn't thinking about perchlorates at the time, but seeing how ammonium perchlorate is very useful in many applications, I wanted to expand into that. Back in 2022 I worked with Naruchan (AKA MysteriusBhoice) to make both sodium and potassium chlorate, and while my yields were not good, the results were fantastic. I made a good deal of extremely pure chlorates and I meticulously noted the processes, pH control, and everything. Then I wanted to get into perchlorate synthesis. I originally had a platinum electrode to use as an anode, but it failed half-way in the synthesis. I did succeed in making some perchlorates, but clearing it away from the remaining chlorate was very difficult, but I ultimately succeeded. I made some ammonium perchlorate with that and it did work in making things like iNAP which I have used, so I know it is at least 'good enough'.

After that I was just tired of chlorates and perchlorates and decided to move onto other things. I wanted to come back to the matter earlier this year, I even made my own PbO2 electrode from my no longer needed MMO electrode, but I did not use it. I instead opted to buy a PbO2 electrode, but my choice could have been better (I should have bought from Feanor Forges from Ebay, maybe I might end up doing that later).

So here was my setup: I used 550g of sodium chloride in a 2000ml 3.5g/l sodium persulfate (made from ammonium persulfate via double displacement) solution and I setup my electrodes 2.5cm apart. The PbO2 anode in the middle with the titanium on the sides. I used clamps (amateurish, I know, but MysteriusBhoice and I found that useful), I ran it for around 92 hours total with an temperature range between 45 and 58C and the voltage was never below 5.4, and the amperage peaked at 25, but did start to drop at the end. I replenished the liquid as it evaporated with more 3g/l sodium persulfate solution.

I decided to filter it from the corroded PbO2 metal and I added some Methylene blue, which should turn purple to indicate the presence of perchlorates, but no color change happened. It remained blue. I am lead to believe that I most probably have chlorate solution and not perchlorate. How pure are the chlorates? Not sure yet, but I still got plenty of sodium chlorate from the 2022 synthesis.

So now that I shared my experiences thus far, what can I do to improve things? I would really like to be 'good enough' at making perchlorates as I am chlorates. Where did I go wrong? Was the current too low?

Deathunter88 - 19-10-2025 at 16:55

Look up how to do the methylene blue test properly, you need to strongly acidify the solution with HCl first.

Radiums Lab - 19-10-2025 at 23:21

Why don't you use KCl? It is better at turning into KClO4. KClO4 is less hygroscopic too.

ManyInterests - 21-10-2025 at 16:14

Quote:

Look up how to do the methylene blue test properly, you need to strongly acidify the solution with HCl first.

I was not aware. Thank you for telling me about that. I am assuming that this link (http://www.chlorates.exrockets.com/tests.html) will have sufficient information? It does not mention HCl for perchlorates though.

Quote:

Why don't you use KCl? It is better at turning into KClO4. KClO4 is less hygroscopic too.

Because I remember making potassium chlorate and sodium chlorate... the sodium chlorate was so so so so much easier than potassium chlorate.I figured the same would be for perchlorates, and since the starting reagent for sodium chlorate and perchlorate is the much more easily and cheaply obtainable sodium chloride I figured I would go that route, and if I want or need potassium perchlorate, I can make some from sodium perchlorate via double displacement with KCl (and I have a good deal of KCl on hand). This is my interest in making sodium perchlorate. Because I want to turn it into ammonium perchlorate mostly.

But I need to mention a development in what happened... I dried all my stuff and I decided to do some simple burn tests. I made a 50:50 mixture with sugar and it ignited readily. the fire wasn't too strong or quick, and it did leave behind a lot of residue... but then I decided to do a different test. Since chlorate/sugar mixtures readily ignite when exposed to sulfuric acid, and I was told that sodium perchlorate/sugar mixtures do not, I decided to try... and I made another 1 gram mixture and put a few drops of sulfuric acid. I heard some crackling and spitting, but no fire. I then put on a few ml of sulfuric acid (pure stuff, not drain opener, BTW) and still no fire. It did crackle, turn a little yellow, and have a putrid, toxic smell (I had to turn on all ventillation to get rid of it and I felt it for a bit).

I did hear that added sulfuric acid to sodium perchlorate will result in sodium sulfate and perchloric acid. Am I correct? Maybe I DID succeed in making some sodium perchlorate? Or maybe it is all sodium perchlorate?

I need to know what tests I can do, and If a good deal of IS perchlorate, I need look up on http://www.chlorates.exrockets.com/chlorate.html to follow the steps to fully destroy all remaining chlorates that do exist so I can make some good pure ammonium perchlorate!

woelen - 21-10-2025 at 23:46

Based on the results of your test with H2SO4, I think that you have perchlorate, but with quite some chlorate impurity.

If you have pure perchlorate, then no yellow color is observed at all, when H2SO4 is added. The yellow color is due to formation of HClO3, which quickly decomposes, one of the decomposition products being the deep yellow ClO2.

Try adding a few drops of H2So4 to your powder, without any sugar in the mix. If it still turns yellow, then you certainly have chlorate in it.

The fact that it does not ignite immediately means that it is not mostly chlorate. The remainder most likely is perchlorate (or less likely, chloride).

Is your mix hygroscopic? NaClO4 is extremely hygroscopic, and obtaining dry crystals of this is very difficult.

Alkoholvergiftung - 22-10-2025 at 00:37

Couldn t you use the Aceton purification methode? Sodiumperchlorate is soluble in aceton chlorate not. If it disolve you can be sure its Perchlorate.

[Edited on 22-10-2025 by Alkoholvergiftung]

Radiums Lab - 22-10-2025 at 03:46

I always suggest you to make KClO4 because it's less hygroscopic and it's easy to store. The solubility at room temp is less but if you heat it enough it's pretty soluble, purification is easy and ion exchange reactions are pretty easy when KClO4 is used compared to NaClO4, advantage of NaClO4 is it's better solubility.

ManyInterests - 24-10-2025 at 16:06

Quote:

Based on the results of your test with H2SO4, I think that you have perchlorate, but with quite some chlorate impurity.

If you have pure perchlorate, then no yellow color is observed at all, when H2SO4 is added. The yellow color is due to formation of HClO3, which quickly decomposes, one of the decomposition products being the deep yellow ClO2.

Try adding a few drops of H2So4 to your powder, without any sugar in the mix. If it still turns yellow, then you certainly have chlorate in it.

The fact that it does not ignite immediately means that it is not mostly chlorate. The remainder most likely is perchlorate (or less likely, chloride).

Is your mix hygroscopic? NaClO4 is extremely hygroscopic, and obtaining dry crystals of this is very difficult.

I just did a test today. I put in 0.82g in a glass and I put in 4ml of sulfuric acid. There was both yellow and red in the liquid. I neutralized the liquid with bicarbonate solution (I should have poured in the solution instead of spraying! I had a small explosion But thankfully nothing got on me and nothing was damaged, even the glass.) So as you put it, it has perchlorate with a good deal of chlorate contamination. I will need to destroy the chlorate with HCl (and I must do very slowly because there will be a large amount of chlorate and chlorine gas is both dangerous and explosive) I assume.

Quote: Originally posted by Alkoholvergiftung

Couldn t you use the Aceton purification methode? Sodiumperchlorate is soluble in aceton chlorate not. If it disolve you can be sure its Perchlorate.

[Edited on 22-10-2025 by Alkoholvergiftung]

Not yet. But I will be doing that tomorrow and post again on the results. I will be grinding up what I have into a fine powder and weigh it before using the appropriate amount of warm acetone to see how much dissolves.

Quote:

I always suggest you to make KClO4 because it's less hygroscopic and it's easy to store. The solubility at room temp is less but if you heat it enough it's pretty soluble, purification is easy and ion exchange reactions are pretty easy when KClO4 is used compared to NaClO4, advantage of NaClO4 is it's better solubility.

Most documentation is about sodium perchlorate though... This makes me wonder. What about barium chlorate and perchlorate? The reason why I ask is that if I can make barium perchlorate, then using that to make ammonium perchlorate will be even easier... since if I use something like ammonium carbonate to do an ion exchange, the resulting barium carbonate is practically insoluble in water, meaning all what will be left in solution is ammonium perchlorate and excess ammonium carbonate, the latter is very easy to get rid of as it decomposes with even mild heating.

ManyInterests - 26-10-2025 at 18:50

Ok so I finally got to trying to dissolve some of my product... and I got something! I measured out 50g of finely powdered stuff and I used 200ml of acetone (an excess, as sodium perchlorate is around 50g per 100ml or so of acetone) and I heated it up to boiling. Then with strong stirring I added all the of the powder. Some of it definitely did dissolve. How much? I don't know. I am drying out the stuff that didn't dissolve so I can weigh it out, but at least I got something.

So I started a 2nd synthesis. This time I am using 600g of sodium chloride, 4g/l persulfate, an 2000ml of water. I put the electrodes MUCH closer (1cm) and the current is able to be much stronger. But my wires are burning out. I think I know why, but one problem is that I will need to halt the synthesis and cut out the corroded part of the wires and bring fresh wire on the electrodes, that does bring the current back up. Clamps are also necessary for a good connection. Electrical wire is no good as it appears to be burning due to the heat.

woelen - 27-10-2025 at 02:29

If you have red material on addition of conc. H2SO4, then you have considerable chlorate contamination. This red/orange material is highly concentrated ClO2 in liquid (dissolved) form, which is very unstable and easily explodes (as you have noticed). From here, I cannot tell how much perchlorate you have, but I am afraid that at best you have a few tens of percent of perchlorate, the rest being mainly chlorate (and possibly some chloride).

The connection at the electrodes with the wires is the most vulnerable part of an electrolysis cell. You need really thick wire and you must protect the wire from the droplets/mist, produced by the electrolysis cell, due to strong bubbling of H2. The mist is very corrosive and electrical wire with thin strands is quickly oxidized away to a dark goo. I used Feanor Forge's electrodes for making chlorate, with his plastic covers, using screw connections and a protective PTFE-like ring, which keeps away the corrosive mist from the connections quite well. Even with that I had issues and had to refresh the connections after a few days of running the cell.

[Edited on 27-10-25 by woelen]

ManyInterests - 27-10-2025 at 06:36

Quote: Originally posted by woelen

If you have red material on addition of conc. H2SO4, then you have considerable chlorate contamination. This red/orange material is highly concentrated ClO2 in liquid (dissolved) form, which is very unstable and easily explodes (as you have noticed). From here, I cannot tell how much perchlorate you have, but I am afraid that at best you have a few tens of percent of perchlorate, the rest being mainly chlorate (and possibly some chloride).

The connection at the electrodes with the wires is the most vulnerable part of an electrolysis cell. You need really thick wire and you must protect the wire from the droplets/mist, produced by the electrolysis cell, due to strong bubbling of H2. The mist is very corrosive and electrical wire with thin strands is quickly oxidized away to a dark goo. I used Feanor Forge's electrodes for making chlorate, with his plastic covers, using screw connections and a protective PTFE-like ring, which keeps away the corrosive mist from the connections quite well. Even with that I had issues and had to refresh the connections after a few days of running the cell.

[Edited on 27-10-25 by woelen]

the explosion was quite unnerving, I am glad I am OK and nothing got busted.

And seeing the contamination makes me wonder how to make best of a bad situation. Chlorates were challenge to me (and they were the first thing I did when I got into chemistry). I got the process down as best I can with what I have, but my yields were always terrible.

I have to cut the wires on a daily basis to ensure proper connection (right now when I woke up the current was 18a, but when I cut the wires it went up to 26.5a)

One other thing that I think I need is more run time. If you said I have a few ten percents then... well, like I said, that is indicative of me of a terrible run, and in my next attempt I need not only more current on average, but considerable longer run time. Chemgineer said he did a similar run (but with no persulfates and a higher concentration of chlorides) for 60 days at 10A and he has very little chlorate contamination. I kept my run for barely 4 days. My current run that has been going on for 1.5 days so far I will try to keep going for 14 days or a little more since the amperage will vary. So maybe 15 days total if I can, or maybe 3 weeks if possible?

He replenished his electrolyte with more chloride. I am doing it with more persulfate solution.

And Feanor Forge's setup is awesome! I legit wish I got his PbO2 setup instead of the crap that I have. In fact, maybe sometime next year I might buy one of his setups just for the hell of it. But for now I will have to make due with what I have.

Speaking of which, you said that I mostly have chlorates in my old batch with maybe some chloride? Many synthesis state to start with chlorate and not chloride. Perhaps I can make an electrolyte with that instead for another run?

Alkoholvergiftung - 27-10-2025 at 08:41

ManyInterests.
In old chemistry book they wrote for Perchlorate manufacture. They used Potassiumchlorate filled it in an sack and hang it in reaction fessel. It must be Chloride free if you have more than 5% Chloride contend no Perchlorate is formed. It must be under 27C. It must be neutral or acidic . They did it with an CO2 bubbler you can buy some diy bubbler on amazon. In alkalien conditions only at the beginning and only with high currents there are small amounts of Perchlorate formed. the Cathode must be only 40%to 45% survace era than the Anode because if you have an current of 150mA cm2 you have max efficency of 54% if you have an current of 190mA cm2 you have 85% (Cathode current). hope this helps
Anode was Platin and Cathode Titan because Nickle gets correded in Perchlorate cell.

[Edited on 27-10-2025 by Alkoholvergiftung]

[Edited on 27-10-2025 by Alkoholvergiftung]

ManyInterests - 27-10-2025 at 15:26

Quote: Originally posted by Alkoholvergiftung

ManyInterests.
In old chemistry book they wrote for Perchlorate manufacture. They used Potassiumchlorate filled it in an sack and hang it in reaction fessel. It must be Chloride free if you have more than 5% Chloride contend no Perchlorate is formed. It must be under 27C. It must be neutral or acidic . They did it with an CO2 bubbler you can buy some diy bubbler on amazon. In alkalien conditions only at the beginning and only with high currents there are small amounts of Perchlorate formed. the Cathode must be only 40%to 45% survace era than the Anode because if you have an current of 150mA cm2 you have max efficency of 54% if you have an current of 190mA cm2 you have 85% (Cathode current). hope this helps
Anode was Platin and Cathode Titan because Nickle gets correded in Perchlorate cell.

[Edited on 27-10-2025 by Alkoholvergiftung]

[Edited on 27-10-2025 by Alkoholvergiftung]

Thanks. I think I can make it work with my potassium chlorate supply. But the details are a bit scant. I am sure I can research it a bit more.

But again... for now I need to make sure my current run finishes OK. I need to cut a fuckload of wires since they are going to keep getting corroded. I am barely 48 hours in and it is being a pain. It isn't THAT bad, but still annoying.

I think I will replenish the electrolyte with persulfate and some sodium chloride going forward. If I do a third run after this (in a few weeks! I hope!) I will use the chlorate that resulted from the previous two runs.

Speaking of which, I would like to know... how can I separate my sodium chlorate from sodium chloride?

ManyInterests - 27-10-2025 at 16:39

I asked chatgpt (through duck.ai) about how to removed sodium chloride from chlorate. I will post it here... is it hallucinating or is it being factual?

Quote:

Selective Precipitation Using Magnesium Sulfate

Using magnesium sulfate (MgSO₄) to selectively precipitate sodium chloride (NaCl) from a mixture of sodium chloride and sodium chlorate can lead to the formation of the following salts:
Resulting Salts

Sodium Chloride Precipitation:
When magnesium sulfate is added to the solution, it reacts with sodium chloride to form magnesium chloride (MgCl₂), which remains soluble. The sodium chloride will precipitate out: MgSO4+2NaCl→MgCl2+Na2SO4(solution)
The precipitation of NaCl can also occur under certain conditions, primarily if there is sufficient concentration or if the ionic strength of the solution changes significantly.

Sodium Chlorate in Solution:
Sodium chlorate (NaClO₃) remains in solution and does not precipitate by this process since it is more soluble than sodium chloride.

Considerations

Stoichiometry:
From 100 g of the 50:50 mixture, there are 50 g of NaCl and 50 g of NaClO₃.
The molar masses are approximately:
NaCl: 58.44 g/mol
NaClO₃: 105.44 g/mol
Moles of each:
nNaCl=58.44g/mol50g≈0.856mol
nNaClO3=105.44g/mol50g≈0.474mol

Steps to Execute the Process

Dissolve Sodium Salts:
Properly dissolve your 100 g of the sodium salts (50 g NaCl and 50 g NaClO₃) in 500 mL of water.

Add Magnesium Sulfate:
Gradually add magnesium sulfate to this solution. The amount needed will depend on the equilibrium and precipitation observed.

Precipitate Formation:
Watch for NaCl precipitation during the process. Monitor the solution clarity and turbidity.

Filtration:
After allowing time for precipitation, filter the mixture. The sodium chloride should be captured on the filter paper.

Washing and Collection:
Wash the precipitated sodium chloride to remove adhering chlorate solution.

Resulting Solution:
The remaining solution should now contain the various soluble salts (mainly the magnesium sulfate and sodium chlorate).

Summary

By adding magnesium sulfate, sodium chloride will precipitate out while sodium chlorate remains in the aqueous phase. You’ll end up with solid NaCl and a solution containing NaClO₃ and dissolved magnesium sulfate (which may also precipitate out as MgSO₄·7H₂O upon cooling if sufficient quantities were added).

If you would like more information on any specific steps or dosages, let me know!

bnull - 27-10-2025 at 18:17

Quote:

When magnesium sulfate is added to the solution, it reacts with sodium chloride to form magnesium chloride (MgCl₂), which remains soluble. The sodium chloride will precipitate out:

Does it make any sense to you? If you were introducing more chloride ions by using magnesium chloride, then yeah, there's the common ion, NaCl is the less soluble of whatever is in solution and would fall to the bottom. But adding magnesium sulfate, where magnesium chloride and chlorate are soluble and sodium sulfate is soluble too, amounts to nothing.

No matter how you ask AI, chances are it will mess up its responses. It has facts and information, not knowledge. ChatGPT is good with translations and finding literature. Don't trust it for the rest. For these things we have articles and books and people.

Alkoholvergiftung - 27-10-2025 at 20:01

I think they used first Potassiumchlorate because it is easyier to clean (recrystallize) than sodiumchlorate.
With lead dioxide it should be possible to go in one run but i think the elektrolysis takes much longer because i ve read when 50% of chloride is conferted to chlorate the rate drops and it goes slower on slower so you need much more time to convert the last 5% than you needed for the first 50%. Thats why they put an bag of chlorate inside the reaction vessle so it holds the chlorate level constant.

woelen - 28-10-2025 at 04:58

I recently made a lot of KClO3, using Feanor Forge's MMO electrodes with the plastic lid. A web page will come about that in due time. Yield is quite good. I used plain KCl, with a little K2S2O8 added. In each run I took appr. 500 grams of KCl and a small teaspoon full of K2S2O8. When the liquid level dropped a few cm, I added more solution of KCl and a pinch of K2S2O8, a little amount on the tip of a big screw driver.
I think I now have appr. 1000 grams of KClO3, recrystallized from distilled water to make it really pure. During the electrolysis I had to take out solid KClO3. I also used a long narrow flower vase to assure that the electrodes did not get stuck in the solid crystal mass. That is a disadvantage of using KCl instead of KClO3, but the great advantage is that you very conveniently can get solid KClO3 totally free from sodium ions. Recrystallizing KClO3 from water also works like a charm. It is really pure (only the slightest opalescence with silver nitrate) after recrystallization, but taking the crystals out of the vase and just briefly rinsing with ice cold water and pressing dry in a coffee filter with paper tissue around it already gives quite a good product (I think better than 99%, some opalescence with silver nitrate, but no real precipitate).

My next experiment will be to make perchlorate. For that I will first use MMO to make a concentrated solution of NaClO3 (with maybe 10% chloride left) and then I'll use that to make NaClO4 with a PbO2 anode (also from Feanor Forge). Run times must be sufficiently long.
One mole of electrons is almost 100000 Ampere-seconds of charge (actually, a little bit less, but there always will be some losses, so in practice this 100000 Ampere-seconds is a good approximation and is convenient for hand-calculations). For one mole of KClO3 you'll need 8 to 10 mole of electrons in a simple home-made cell. I needed well over 1 week running at 10 A, using a CC/CV power supply, limited at 10A/4.5V. Cell voltage started at 3.3 volts or so. I switched it off, when cell voltage went well over 4.1 volts.

For th NaCl cell, I simply will run it for well over a week at 10A. There will be no visual feedback, as NaClO3 is much more soluble in water. After that, I'll switch to PbO2 and run for another two days, maybe 3 days. Going from NaClO3 to NaClO4 only requires 2 electrons per ion. On Feanor Forge's website I read about issues with cells, working perfectly fine up to the NaClO3 stage and then stopping at that point, giving no NaClO4. I hope I will not be one of those people. I have the impression that making perchlorate is a matter of art, some luck, and maybe a little science

markx - 28-10-2025 at 10:19

Perchlorates can be finnicky stuff and sometimes the synthesis halts or delays itself for no obvious reasons.....I've had my fair share of adventures with it. But usually given enough time and keeping things from extremes (cell voltages, currents, additive package) it will complete itself at some point and produce a nice batch of product. Even if things seem not to progress good at all starting off.
I've even managed to witness the direct formation of KClO4 on a Pt coated anode in saturated KClO3 solution. It formed as a loose layer of cristals that flaked off and collected as a pile under the anode. Quite a sight it was, as all the sources at that time pointed towards this kind of process being impossible

https://www.youtube.com/watch?v=zD9PlBT1laM

Alkoholvergiftung - 28-10-2025 at 10:57

Sometimes is the imposible possible. Sometimes Perchlorate emerge in alkalien cells. they think if the bubbles of gas on the anode and cathode mix and stir together it can be formed there also (as an example). But an direct conversion on pt anode is an feat.

[Edited on 28-10-2025 by Alkoholvergiftung]

ManyInterests - 28-10-2025 at 16:22

Quote:

Does it make any sense to you? If you were introducing more chloride ions by using magnesium chloride, then yeah, there's the common ion, NaCl is the less soluble of whatever is in solution and would fall to the bottom. But adding magnesium sulfate, where magnesium chloride and chlorate are soluble and sodium sulfate is soluble too, amounts to nothing.

No matter how you ask AI, chances are it will mess up its responses. It has facts and information, not knowledge. ChatGPT is good with translations and finding literature. Don't trust it for the rest. For these things we have articles and books and people.

Now that I think about it I feel like an idiot... yeah, this isn't going to work. I'm going to try to coax it for sources and other information... maybe it might accidentally tell me what I need to do. Speaking of which what can I do about sodium chloride left over?

Quote:

I recently made a lot of KClO3, using Feanor Forge's MMO electrodes with the plastic lid. A web page will come about that in due time. Yield is quite good. I used plain KCl, with a little K2S2O8 added. In each run I took appr. 500 grams of KCl and a small teaspoon full of K2S2O8. When the liquid level dropped a few cm, I added more solution of KCl and a pinch of K2S2O8, a little amount on the tip of a big screw driver.
I think I now have appr. 1000 grams of KClO3, recrystallized from distilled water to make it really pure. During the electrolysis I had to take out solid KClO3. I also used a long narrow flower vase to assure that the electrodes did not get stuck in the solid crystal mass. That is a disadvantage of using KCl instead of KClO3, but the great advantage is that you very conveniently can get solid KClO3 totally free from sodium ions. Recrystallizing KClO3 from water also works like a charm. It is really pure (only the slightest opalescence with silver nitrate) after recrystallization, but taking the crystals out of the vase and just briefly rinsing with ice cold water and pressing dry in a coffee filter with paper tissue around it already gives quite a good product (I think better than 99%, some opalescence with silver nitrate, but no real precipitate).

My next experiment will be to make perchlorate. For that I will first use MMO to make a concentrated solution of NaClO3 (with maybe 10% chloride left) and then I'll use that to make NaClO4 with a PbO2 anode (also from Feanor Forge). Run times must be sufficiently long.
One mole of electrons is almost 100000 Ampere-seconds of charge (actually, a little bit less, but there always will be some losses, so in practice this 100000 Ampere-seconds is a good approximation and is convenient for hand-calculations). For one mole of KClO3 you'll need 8 to 10 mole of electrons in a simple home-made cell. I needed well over 1 week running at 10 A, using a CC/CV power supply, limited at 10A/4.5V. Cell voltage started at 3.3 volts or so. I switched it off, when cell voltage went well over 4.1 volts.

For th NaCl cell, I simply will run it for well over a week at 10A. There will be no visual feedback, as NaClO3 is much more soluble in water. After that, I'll switch to PbO2 and run for another two days, maybe 3 days. Going from NaClO3 to NaClO4 only requires 2 electrons per ion. On Feanor Forge's website I read about issues with cells, working perfectly fine up to the NaClO3 stage and then stopping at that point, giving no NaClO4. I hope I will not be one of those people. I have the impression that making perchlorate is a matter of art, some luck, and maybe a little science

I might as well make more sodium chlorate. I mean the previous run that I can reuse them, after all, there is probably plenty of chlorate in there to be turned into perchlorate.

Right now, I am going to see how long I can keep it going. I am not sure if I can accomplish my intended goal of 3 weeks, but I can definitely do it for a week and a day at least. I will still do my best to make it go 2 weeks. If a longer run time will make more perchlorate.

bnull - 29-10-2025 at 03:30

Quote:

Speaking of which what can I do about sodium chloride left over?

I was preparing a perchlorate (or was it chlorate) cell the other day but didn't have a power supply that would work with the electrodes I was going to use. I'll look into it and see what I can find.

Alkoholvergiftung - 29-10-2025 at 06:56

Now i found the artikel its in german and from the Chedde Company. They write Perchlorate form at ph10 too.

Attachment: Perchlorate5_1.pdf (314kB)
This file has been downloaded 116 times

ManyInterests - 29-10-2025 at 16:36

Quote: Originally posted by Alkoholvergiftung

Now i found the artikel its in german and from the Chedde Company. They write Perchlorate form at ph10 too.

Thank you! I will use the miracle of translation software to make it English and see what I can learn! Also makes me wish I spent a little more time learning German!

Quote: Originally posted by bnull

Quote:

Speaking of which what can I do about sodium chloride left over?

I was preparing a perchlorate (or was it chlorate) cell the other day but didn't have a power supply that would work with the electrodes I was going to use. I'll look into it and see what I can find.

You made me forget... I think if worst comes to comes to worst, I will pull out my IR-TI MMO (using a stainless steel ruler for a cathode) and make a setup to allow for conversion of all chloride into chlorate, and then switch to the PbO2 setup. I am starting to think that the whole starting from chloride thing is a giant mistake. I am assuming that if I have a mixture of chloride, chlorate, and perchlorate, the perchlorate and chlorate will be unaffected by that.

Also I seriously am considering shelling out another 200$ in a few months on Feanor Forge's setup. But like I said, I want to run this one to its logical course before buying anything.

markx - 30-10-2025 at 17:06

Quote: Originally posted by Alkoholvergiftung

Sometimes is the imposible possible. Sometimes Perchlorate emerge in alkalien cells. they think if the bubbles of gas on the anode and cathode mix and stir together it can be formed there also (as an example). But an direct conversion on pt anode is an feat.

[Edited on 28-10-2025 by Alkoholvergiftung]

It quite consistently forms in alkaline cells according to my experience....I've done numerous direct full conversions of Cl- to ClO4- in single runs with Pt coated Ti anode and Ti cathodes. No additives or pH corrections at any stage, just let it tick along at a minimum cell voltage which still enables reasonable current flow (less than 5V), top up with water as required (or chlorate solution) and it usually works out just fine. The solution after the ClO3- stage is quite alkaline, but it seems to pose no obstacle for further ClO4- formation. Nor does the residual Cl- content, since it reaches an equilibrium concentration parallelly forming during perchlorate synthesis stage anyways (even if one was to start out with pure chlorate solution). I've had no sudden passivation or other destructive events happening at the chlorate formation stage end. It just passes gradually over to perchlorate synthesis and keeps on going. But as the ClO3- is depleted and the run nears the full conversion limit, the passivation can set in quite suddenly and the anode gives up it's ghost. The same is true if one pushes the cell voltage past 5V. It steeply raises the anode polarisation and intensifies competitive reactions (passivation or degradation due to excessive O2 formation e.g.).

Patience and time are your allies in this game....don't fiddle with the system nor push the cell to the limits and just give it time to do it's thing. A month of constant running was about my realistic and repeatable pace for a full conversion of a 3l cell starting from chloride. Apart from adding electrolyte to top off the lost volume I basically ran it unsupervised and it worked like a charm.
Just accept the fact that any anode beside a solid chunk of Pt is pretty much expendable when a near full conversion of ClO4- is required. One can halt sooner and use selective precipitation and further purification to harvest the perchlorate and push a bit more life out of the anode, but eventually it shall passivate or disintegrate (in a few runs). The conditions are way harsher than during chlorate formation which can be run seemingly indefinitely with a MMO and some common sense.

Alkoholvergiftung - 31-10-2025 at 10:05

oh than i always did the fals voltage for perchlorates. literature wrote 5,5V-6,5V

markx - 31-10-2025 at 11:19

Quote: Originally posted by Alkoholvergiftung

oh than i always did the fals voltage for perchlorates. literature wrote 5,5V-6,5V

Not that it is false to use higher voltages, but unduly harsh on the anodes in my experience. The industry aims for max yields and productivity and hence perhaps the high voltages are advocated and have settled in the model as a dogmatic element. I also got the strong theoretical pre-experimental impression from literature that one needs above 5V of cell voltage to even enable the formation of perchlorates....does not seem like it really after the experiments I ran and the yields I got.
The practical approach that I took after burning some anodes real quick at high potentials was to limit the cell voltage to the minimum that still enables reasonable current flow through the system. Reasonable being on the order of about 7-10A for a 3L cell at the perchlorate stage in my case. This was achievable below 5V. The simplified reasoning being that if side reactions that occur on lower anode polarisation levels (lower current density due to lower cell voltage) hinder the formation of perchlorate synthesis then at higher polarisation they shall be further increased and thus not much shall change except the electrode wears quicker due to new side reactions being called to life. Hence if reasonable current flow is enabled then one has no need to push it further. Seemed to work for my purposes, but I do not claim that this is "THE RIGHT WAY"

Everyone has got a different setup and different nuances....whatever seems to work in any particular case is fine. All that I'm advocating is that "what works" might have a broader reach of parameters than that being claimed in many mainstream references.

ManyInterests - 31-10-2025 at 18:23

Quote: Originally posted by markx

Quote: Originally posted by Alkoholvergiftung

[Edited on 28-10-2025 by Alkoholvergiftung]

Your mention of patience is my take away. I think I've managed to stabilize my setup for now. Sure the current is far from ideal, but it is probably the best given the circumstances. I will try to keep it running for a few weeks if I can to see if I can turn what I have mostly into perchlorate, or at least have a decent amount of perchlorate in my run. I've recently been replenishing with both persulfate and additional chloride.

ManyInterests - 2-11-2025 at 18:34

I wanted to put this in an edit, but I couldn't. I want to put the results of my old run into the current run when replenishing the electrolyte. I will obviously need more run time, but I am OK with that.

ManyInterests - 9-11-2025 at 15:54

I had to move my setup indoors with proper ventilation to protect it from the increasing cold outside. I realize that this does mean I can keep it running for a good long time. So 30 days or more is not out of the question! I added all my previous run days ago and will just replenish with sodium persulfate solution (I had added 225g of sodium chloride previously. I don't want to add any more).

bnull - 13-11-2025 at 17:30

Quote: Originally posted by bnull

Quote:

Speaking of which what can I do about sodium chloride left over?

I was preparing a perchlorate (or was it chlorate) cell the other day but didn't have a power supply that would work with the electrodes I was going to use. I'll look into it and see what I can find.

Quite late but...

Attachment: chlorates_and_perchlorates.pdf (3MB)
This file has been downloaded 64 times

ManyInterests - 16-11-2025 at 18:37

Thanks for the PDF. I will download and review later.

One thing I remember about removing chlorides is a lesson I learned from 2022... just hook up an electrolysis of with my solid IR-TU MMA (one that has produced a lot of excellent chlorates and has a near 100% converstion) and just give it a run for a while, it'll turn the chlorides into chlorates, which then can be put on the PbO2 setup to turn them into perchlorates.

Right now moving my setup indoors has done well to keep the temperature up and I worked to fix the corroding connections (and there is a lot of salt creep developing) that is reducing the current. I was able to get the amperage up from a low 5-12 back to 21-17. Which should help things.

So far I have been running this cell for more than 3 weeks. I plan on at least 5 weeks now. I just hope that I will have mostly perchlorate by them (or all perchlorates). I really want this to work.

My total run would include 725g of chloride + 480g of my previous run (a mix of chloride and chlorates with only a little perchlorate). I am replenishing my electrolyte only with persulfate solution, not just distilled water. Or maybe I should be using just distilled water at this point?

ManyInterests - 27-11-2025 at 16:23

I am almost at my 5th week and I will be halting the synthesis this Saturday (November 29th). The amount of salt creep on the beaker and in the container I put it in is unbelievable. Probably due to the mist that came out due to the heat, and that is what makes me want to get this done with. I don't know if that stuff is chlorate or perchlorate (I am hoping the latter) which is why I intend to pour out the contents and filter out the PbO2 stuff that came out before boiling it. I will then dissolve the salt creep and filter out any insolubles before boiling that stuff down, too.

The electrolyte has been a lot clearer than before, too. I really hope I have a good amount of perchlorate at this stage, and I hope the salt creep didn't result in too much loss. Keeping this indoors (there are no odors at all coming out right now) has done a lot to keep the temperature high, which does help to encourage synthesis, but probably isn't doing my anode any favors.

ManyInterests - 12-12-2025 at 13:58

OK, so after halting everything and evaporating the water fully and grinding it up (there was a smell of chlorine as I did so, but it is gone now), and I ended up with a yield of around 1240g. The burn rate is slow and with little residue, and I did three methylene blue tests. All used 1g of my powder. The first was the least impressive and worst. I added too much water (30ml) and I used concentrated methylene blue and I only added an acid (in this case 10% vinegar) in the end. Yes I was using an LLM and it was stupid. It did turn a strong violet though.

The second test was better, I added a few drops of sulfuric acid to 10ml of water with the powder in it, then another drop of of concentrated meythlene blue. I also got a strong violet color that very slowly turned blue over 24 hours.

the third test had the same setup, except I diluted the methylene blue in 10ml of water (one drop in 10 ml) before adding a few drops of that into another acidific solution, and this time it did dissipate purple slightly and it turned blue and remained that way for 24 hours.

Did I succeed? Do I have plenty of sodium perchlorate?

Mister Double U - 12-12-2025 at 18:49

Hello ManyInterests,

When I made Sodium Perchlorate many years ago, I was using roughly this route (has been 10+ years, so cut me some slack here):

Step 1: Electrolyze NaCl to make NaClO3.
I had a MMO anode capable of generating Oxygen - the ones which do not passivate.
I think I went to ~130% of the calculated run time and conversion was almost complete (explain in next step why I think that).

I also like to add the Faraday equation for calculating run time:

I * t = n * Z * F

I: Current [A]
t: Time [s]
n: Molar Amount [mol]
Z: Number of electrons needed for the reaction [e-]
F: Faraday Constant 96485[C/mol]

If you divide the equation by 'I' you get:
t = (n * Z * F) / I

Step 2: Boil down the cell liquor to a little bit more than saturation (I remember NaClO3 was very difficult to crystallize). Back then this was done in a ceramic plated cooking pot. Boil the solution down to the point that a skin forms on the surface when blowing air on it and then maybe a little bit more. If you stop too early, nothing crystallizes and if you get it right, a lot crystallizes. These 2 points are very close together (that was very weird to me). Then place the solution in a freezer which goes to at least -10C. NaClO3 forms nice big cubic crystals. Some of them were measuring ~4mm on the edges.
Anyway, I do not think there was much NaCl left at the time, because none crystallized out at any time in the boiling down phase.
Lastly, I did the crystallization to purify the intermediate product. I was using self-made PbO2 electrodes at the time and I remember them being quite sensitive to Cl[-] and [OH-].

Step 3: I ran the ClO3[-] to ClO4[-] conversion. PbO2 anode performed well without any brown stuff in the liquor - just some bigger pieces broken off and at the bottom of the cell.
When conversion comes close to the end you will start to smell Ozone.
After that you let it run a day longer and take a small sample of the cell liquor and mix it with conc. HCL. Then heat it to boiling point. If sample turns yellow, you let the cell run another day. After a couple of days the Ozone smell is really strong and the HCl test does not turn yellow anymore -> Then you have an almost pure solution of NaClO4 :-).
As a side note, I believe the conversion from Chlorate to Perchlorate took about 3x the calculated run time.

Btw. I did not use any cell additives for any of the steps at this time (Later on, I used CaCl2 addition to form a diaphragm on the cathode when I made Chlorates). I saw the addition of persulfates being mentioned a couple times, but I will admit, that I do not understand how these work in a Chlorate cell - maybe someone can give me a hint.

Hope that helps & friendly greetings!

[Edited on 13-12-2025 by Mister Double U]

Alkoholvergiftung - 12-12-2025 at 23:54

Manyinterests. You can desolve your Sodiumperchlorate in Aceton. Sodiumchlorate is insoluble. So you can purify and see how much Perchlorate you have.

ManyInterests - 14-12-2025 at 12:18

Thank you guys,

Quote:

Hello ManyInterests,

When I made Sodium Perchlorate many years ago, I was using roughly this route (has been 10+ years, so cut me some slack here):

Step 1: Electrolyze NaCl to make NaClO3.
I had a MMO anode capable of generating Oxygen - the ones which do not passivate.
I think I went to ~130% of the calculated run time and conversion was almost complete (explain in next step why I think that).

I also like to add the Faraday equation for calculating run time:

I * t = n * Z * F

I: Current [A]
t: Time [s]
n: Molar Amount [mol]
Z: Number of electrons needed for the reaction [e-]
F: Faraday Constant 96485[C/mol]

If you divide the equation by 'I' you get:
t = (n * Z * F) / I

Step 2: Boil down the cell liquor to a little bit more than saturation (I remember NaClO3 was very difficult to crystallize). Back then this was done in a ceramic plated cooking pot. Boil the solution down to the point that a skin forms on the surface when blowing air on it and then maybe a little bit more. If you stop too early, nothing crystallizes and if you get it right, a lot crystallizes. These 2 points are very close together (that was very weird to me). Then place the solution in a freezer which goes to at least -10C. NaClO3 forms nice big cubic crystals. Some of them were measuring ~4mm on the edges.
Anyway, I do not think there was much NaCl left at the time, because none crystallized out at any time in the boiling down phase.
Lastly, I did the crystallization to purify the intermediate product. I was using self-made PbO2 electrodes at the time and I remember them being quite sensitive to Cl[-] and [OH-].

Step 3: I ran the ClO3[-] to ClO4[-] conversion. PbO2 anode performed well without any brown stuff in the liquor - just some bigger pieces broken off and at the bottom of the cell.
When conversion comes close to the end you will start to smell Ozone.
After that you let it run a day longer and take a small sample of the cell liquor and mix it with conc. HCL. Then heat it to boiling point. If sample turns yellow, you let the cell run another day. After a couple of days the Ozone smell is really strong and the HCl test does not turn yellow anymore -> Then you have an almost pure solution of NaClO4 :-).
As a side note, I believe the conversion from Chlorate to Perchlorate took about 3x the calculated run time.

Btw. I did not use any cell additives for any of the steps at this time (Later on, I used CaCl2 addition to form a diaphragm on the cathode when I made Chlorates). I saw the addition of persulfates being mentioned a couple times, but I will admit, that I do not understand how these work in a Chlorate cell - maybe someone can give me a hint.

Hope that helps & friendly greetings!

Thank you for that information. Yes you seem to have done better than me with it, and maybe I will try again next time using my own home made PbO2 anode (I did make one from an old MMO anode I don't want anymore, I used lead nitrate as coating. I saw a video on doing it and followed it). But at this point I am more interested in purifying what I have from any chlorate.

Quote:

Manyinterests. You can desolve your Sodiumperchlorate in Aceton. Sodiumchlorate is insoluble. So you can purify and see how much Perchlorate you have.

That does work, but it still needs HCl purification. There must be no chlorate in it in order to safely make ammonium perchlorate.