Sodium chlorate cell questions.

[THEONE]

I got few questions about sodium chlorate production. Its likely that my questions would already be answered in the big (per)chlorate topic but it will take my whole life to read it.

 

I am planning to make sodium chlorate and then transfer it to another cell for perchlorate. I recently learn that NaCLO4 is soluble in acetone while NaCLO3 is not. That is a really good way to separate NaCLO3 from NaCLO4 but i really can not find any way to separate NaCLO3 from NaCL. I guess with their solubility differences can be separated but always will be some NaCL right? destroying your anode.

 

I read also that you can actually run your cell till NaClO3 start to ppt out. At first looks like a good way to separate them but after waching Nurdrage video about his KCLO3 production, he claims that CLO3 CAN BE REDUCED at the cathode, that is why he used a small cathode to minimise the surface area. To be honest, first time i hear something like this. Is that true? And how much does it actually affect the cell efficiency? If that is true, is there any posobility that a saturated NaCLO3 solution wont produce more CLO3 due to this effect ?

 

 

P.S. I want to comment something with my homemade MNO2 anode. DO NOT ever bother with MNO2 anode cause their production and efficiency is crap. I have now a new MMO anode and i will try again with that one. Hopefully everything will go fine.

 

Thanks.

Edited November 11, 2019 by THEONE

[Arthur]

If you start with a saturated solution of NaCl then you can electrolyse that to about a 40% saturated solution of NaClO_3. The solubility if the sodium perchlorate is greater than the solubility of the sodium perchlorate, which is again greater than the solubility of the sodium chloride. Only when you convert to the Potassium perchlorate do solubilities prefer the precipitation of the wanted product -perc. The temperature and rate of addition of the KCl determines the size mix of the perc powder grains.

 

There is a reason why industry uses platinum and lead dioxide for the perc cell -they are the only ones that work even though platinum is expensive and lead dioxide needs careful manufacture and careful handling.

 

For the chlorate cell MMO is easily available and very economical. Always run electrodes a bit below rated current, it seriously improves their life.

[Arthur]

If you are not willing to read the threads and do some outside research then it's unlikely that those who are part of the (per)chlorate and Bucket cell threads will spoon feed you with the details just as you want them.

[THEONE]

Arthur i did not mention the potassium salts because i am not going to use them. I am interested in sodium because sodium can be changed to any other salt like potassium or ammonium. I have already plenty of knowledge about the subject, as i said before, i have already done it but with homemade MNO2 electrodes but i have never seen a good way to separate NaCLO3 from NaCL.

 

In addition, the reduction of CLO3 at the cathode is something that i hear it for 1st time and i am not really sure how it actually affects the efficiency or whatever. It is well known that the rule of thumb is to keep the surface are of the 2 electrodes at 1:1 BUT if the above fact is true then the cathode should have a smaller surface area than the anode.

 

I have read most part of (per)chlorate and Bucket cell threads in the past but i did not see any information about the above questions.

Edited November 11, 2019 by THEONE

[Arthur]

The simple fact is that both chloride and chlorate are soluble so it's hard to remove one from the other with good accuracy and yield. That's why the potassium salt is added to force the oxidised salt to precipitate before the unoxidised salt.

[THEONE]

With potassium salts its a lot easier but you are restricted to potassium salts, while with sodium salts you can make anything with metathesis reaction. I am not going to use potassium at all.

[WSM]

There's no need to read the whole (per)chlorate thread. Most of my posts about sodium chlorate cells are in just the past four years or so. Before that, most of my discussions were about potassium salts, I think.

 

My interest in making sodium chlorate came from my perchlorate experiments and (for me) the lack of availability of commercial sodium chlorate.

 

Before I ventured into making sodium chlorate, I knew practically nothing about it, but have since learned a great deal through practice.

 

WSM

[WSM]

I looked back through the (per)chlorate thread and believe my sodium chlorate research began with post 3628, in late 2015, if I'm not mistaken.

 

See if any of that helps.

 

Good luck!

 

WSM

[Arthur]

Currently the only long term process for chlorates and perchlorates involves electrolysing sodium chloride solution in a warm to hot solution -producing the sodium salt. However this liquor is very hard to separate out without the process of making potassium salts. If you don't want the potassium salt then you have to sort out how to separate the perc from the chlorate from the chloride.

[WSM]

If you don't want the potassium salt then you have to sort out how to separate the perc from the chlorate from the chloride.

 

I managed it by running the chlorate cell long enough to minimize the chloride. Next, I dropped out sodium chlorate crystals in a zero degree chiller, and recycled the electrolyte by adding more chloride brine and continuing the chlorate step.

 

After I had some pure sodium chlorate crystals, I used it to make an electrolyte for a perchlorate cell, and run it.

 

When the perchlorate cell reaches the end of its run, I treated the impure perchlorate solution with sodium metabisulfate solution to neutralize the residual chlorate.

 

That done, I dropped in potassium chloride solution which immediately dropped out potassium perchlorate as fine, white crystalline powder.

 

The next step is to dilute the sodium residue and remove it with enough washings to leave the KClO4 clean. Next, dry and store the potassium perchlorate.

 

WSM

Edited November 20, 2019 by WSM

[THEONE]

I managed it by running the chlorate cell long enough to minimize the chloride. Next, I dropped out sodium chlorate crystals in a zero degree chiller, and recycled the electrolyte by adding more chloride brine and continuing the chlorate step.

 

After I had some pure sodium chlorate, I used it to make an electrolyte for a perchlorate cell, and run it.

 

When the perchlorate cell reaches the end of its run, I treated the impure perchlorate solution with sodium metabisulfate solution to neutralize the residual chlorate.

 

That done, I dropped in potassium chloride solution which immediately dropped out potassium perchlorate as fine, white crystalline powder.

 

The next step is do dilute the sodium residue and remove it with enough washings to leave the KClO4 clean. Next dry and store the potassium perchlorate.

 

WSM

 

Can you tell me pls your calculations in order to stop the (per)chlorate cell? I was thinking that maybe a bit dangerous because anodes will wear off easily in low chloride/chlorate concentrations right?

 

P.S. Thaks a lot both of you for your help

[THEONE]

Ok, I just started my cell. It is an 8L cell with 2kg of KCL running with a PC power supply. I really dunno the Amps that it is running but it has an output of 20A at 5v. I will add some more salt these days, probably NaCl because 8L for 2Kg salt is not that much, it can take more.

[Arthur]

First you need to know how much chloride you cell contains that is crucial to knowing and predicting the cell conditions and progress.

 

Swede's posts contain the maths of mass/amphours and efficiency from which you can predict how many amphours are needed.

 

MY theory is that you should make a saturated solution (tables on wikipedia) of chloride then electrolyse it for the theoretical number of amp hours for 100% completion, then switch off. (What is left as chloride makes a suitable buffer against the low chloride harsh environment that kills electrodes.) You could then resaturate the cell with chloride and electrolyse for that much again. This should give you as much concentration of chlorate in the solution as reasonably possible. When you have chlorates or perchlorates in solution it's up to you to chose what you use to ppt out the salt that you want without contamination the liquor so that it can be recycled extensively.

[WSM]

Can you tell me pls your calculations in order to stop the (per)chlorate cell? I was thinking that maybe a bit dangerous because anodes will wear off easily in low chloride/chlorate concentrations right?

P.S. Thaks a lot both of you for your help

If you know or can guess the concentration of your sodium chlorate electrolyte in Moles (a good reason to start with dry sodium chlorate crystals and distilled water), before starting to make sodium perchlorate, it helps in figuring how long to run your cell to add an equal number of Moles of oxygen.

 

NaClO3 + O --> NaClO4

 

This is just an estimate and will give you a guideline. If things change dramatically during the run, that's a good indication that the run should be stopped.

 

I monitor the voltage, amperage and temperature (at least); and abrupt changes in any or all of these are valuable clues as to what's happening in the cell processes.

 

I'll double check my thoughts with a friend and fellow amateur electrochemist, and report back any additional thoughts or corrections he may have to offer.

 

WSM

[WSM]

Ok, I just started my cell. It is an 8L cell with 2kg of KCL running with a PC power supply. I really dunno the Amps that it is running but it has an output of 20A at 5v. I will add some more salt these days, probably NaCl because 8L for 2Kg salt is not that much, it can take more.

 

I hope I misunderstood you. I don't think mixing potassium and sodium electrolytes during a cell run is a good idea.

 

As for knowing the output of your power supply, inexpensive meters are available online from eBay and other sources. I've used combination meters to read the voltage AND amperage output of power supplies I use, while they're in operation.

 

The volt meter is connected in parallel, while the ammeter is connected in series with the power supply output leads.

 

WSM

[WSM]

Arthur's suggestion to read Swede's posts are excellent. His blog posts have a wealth of information and are a great resource.

 

Actually, Arthur's entire post looks like a good basis to start with.

 

WSM

Edited November 19, 2019 by WSM

[Arthur]

It is not possible to make sensible and quantifiable progress when you take "some" chemical and dissolve it in "some" water.

[WSM]

It is not possible to make sensible and quantifiable progress when you take "some" chemical and dissolve it in "some" water.

True. You may or may not get "some" oxidizers!

 

By the way, I DO like quantifiable!!!

 

WSM

Edited November 19, 2019 by WSM

[THEONE]

Why is not a good idea to mix both salts ? I read somewhere that adding NaCL to KCL actually increase the efficiency a bit due to Na ions

[Arthur]

As the chlorate is produced the K ions will ppt it out.

[THEONE]

As the chlorate is produced the K ions will ppt it out.

 

Yea Kclo3 will ppt out and NaCL will remain in solution. I do not find any reason why it is not good to add Nacl to Kcl cell

[WSM]

Yea Kclo3 will ppt out and NaCL will remain in solution. I do not find any reason why it is not good to add Nacl to Kcl cell

 

Aside from adding sodium contamination to your potassium salt, requiring a thorough cleaning before use in color compositions?

 

I have enough trouble removing sodium residue from the potassium perchlorate I've made, let alone from potassium chlorate, which is more soluble than the perchlorate.

 

Please consider the suggestion more carefully. Thanks.

 

WSM

Edited November 22, 2019 by WSM

[THEONE]

Hmm ok WSM i see your point, thanks for your suggestion

[THEONE]

Ok today for some reason my PSU stop... and it did not want to start again... I tried another PSU and the same was happened....

 

Maybe the cell draw too much Amps and they burned out... I am not 100% sure tho, 1st time is happening to me.

[Arthur]

You don't know how much salt or water or current that you use. I don't know if you can be helped.