making potassium (per) chlorate

[WSM]

Yes !!!! That is great news!!!!!!!!!

We all have been missing his presence.

 

To Swede:

Welcome back, old friend!

 

WSM

Edited May 31, 2012 by WSM

[pdfbq]

In the sodium process, the end result is a concentrated sodium perchlorate solution, free of chlorate ions.

Now that would be nice but unfortunally is not true. If you try to run until no chlorate ions are detectable anymore your anode would be destroyed.

 

My experience is that you should stop when te current goes up. That is harder to control than it seems because this happens quite quickly, like in some hours. This means when it happenpens in the night your anode will be golden brown, still alive thoug but probably with less platina.What would be nice is some electric circuit that helps you with this.

 

My pt anodes is still alive after about eight kilos of perc and two kilo of ammonium perc but worn. Iirc in industry a method is used to recollect the lost platina from the cell, but I dont know how and dont know if we could use that technique.

 

Then if we desire potassium perchlorate we add a concentrated potassium chloride solution and the greatly less soluble potassium perchlorate drops out of solution immediately. After vacuum filtering and a cold DI water rinse, the KP is dried and stored. It sounds easy but it involves a lot of handling. If we set up for it, it's just the routine we go through to get our desired product.

This is not that much work but the product you will end up with is massively sodium contaminated. Aftr that you have to recristallize your perc two times, fist time tap second time demi water to get rid of all the sodium. Personaly i find that the most work. Edited May 31, 2012 by pdfbq

[Arthur]

Unless you have lead dioxide anodes then the perc production is in two stages, chloride to chlorate (with big traces of remaining chloride) then you purify the chlorate free of chloride. AFTER this you can use a Pt electrode and make perc,

 

Adding KCl will ppt out the KPerc and leave the solution full of chloride ready to restart.

[WSM]

Well, I did leave out a few steps I felt were understood. I see I shouldn't have done that.

 

The chlorate ions in the perchlorate solution (I'm talking about sodium salts here) need to be neutralized by metabisulfites before the potassium chloride is added to drop out the potassium perchlorate (which, of course needs to be cleaned of sodium contamination before use).

 

WSM

 

[quote name=pdfbq' timestamp='1338486993'

post='96005]

Now that would be nice but unfortunally is not true. If you try to run until no chlorate ions are detectable anymore your anode would be destroyed.

 

My experience is that you should stop when te current goes up. That is harder to control than it seems because this happens quite quickly, like in some hours. This means when it happenpens in the night your anode will be golden brown, still alive thoug but probably with less platina.What would be nice is some electric circuit that helps you with this.

 

My pt anodes is still alive after about eight kilos of perc and two kilo of ammonium perc but worn. Iirc in industry a method is used to recollect the lost platina from the cell, but I dont know how and dont know if we could use that technique.

 

This is not that much work but the product you will end up with is massively sodium contaminated. Aftr that you have to recristallize your perc two times, fist time tap second time demi water to get rid of all the sodium. Personaly i find that the most work.

[pdfbq]

Well, I did leave out a few steps I felt were understood. I see I shouldn't have done that.

Well, assumption is the mother of all screw ups

[dangerousamateur]

then you purify the chlorate free of chloride. AFTER this you can use a Pt electrode and make perc,

How is this made?

[WSM]

"then you purify the chlorate free of chloride. AFTER this you can use a Pt electrode and make perc,"

How is this made?

 

Arthur made the original comment and dangerousamateur asked the question. If I may, I'd like to try to answer it.

 

If I understand the question correctly, he's asking, "How does one make chloride-free chlorate?"

 

The answer is, it depends.

 

First, are you using sodium or potassium chloride?

 

If you use sodium chloride to make sodium chlorate, the resulting product is more soluble than the starting material. So separation is accomplished by concentrating the solution and lowering the temperature to the point where the chloride crystallizes out, leaving the more soluble chlorate in solution. I will leave it to your imagination (or further research) to determine for yourself how to best accomplish the concentrating and chilling methods required to separate the sodium chlorate from the sodium chloride.

 

If you use potassium chloride to make potassium chlorate, the resulting product is less soluble than the starting material. As a result, as the chlorate ion concentration increases and begins to reach saturation, the potassium chlorate starts to drop out of solution as small, flat crystals (resembling snowflakes somewhat); leaving the chloride in solution. The small crystals usually grow into a heavy solid mass if left in the cell and solution long enough.

 

All of these reactions are based on the salt concentration of the solutions and temperature. Some convenient charts exist that show the relationship clearly, and are an excellent guide to assist us in designing systems to win the products we desire. I got these charts from Swede and am attaching them below.

 

Solubilities of Common Salts.pdf

Solubility vs Temperature Chart.pdf

 

I believe Swede found these charts in other sources or from another forum and possibly shared them here before.

 

WSM

Edited June 3, 2012 by WSM

[WSM]

Well, assumption is the mother of all screw ups

 

At least you did the right thing and brought it to my attention, so I could clarify my intended meaning. Thanks.

 

WSM

[frank]

" If you use sodium chloride to make sodium chlorate, the resulting product is more soluble than the starting material. So separation is accomplished by concentrating the solution and lowering the temperature to the point where the chloride crystallizes out, leaving the more soluble chlorate in solution. I will leave it to your imagination (or further research) to determine for yourself how to best accomplish the concentrating and chilling methods required to separate the sodium chlorate from the sodium chloride. "

 

 

 

You will get no Sodium Chloride to come out of a solution that has been let run to (say approx.) 50 grams per liter Chloride (or even if only let run to 150grams per liter Chloride). If this said solution was started off with (approx.) 320 grams per liter Sodium Chloride then 270 grams (per liter) of the Chloride will have been converted into approx. 270 * 1.8 = 486 grams (per liter) Chlorate.

So you will have a solution that has about 50 grams per liter Chloride and 486 grams per liter Sodium Chlorate. Cooling might get you some Chlorate, but no Chloride will come out of solution. (the above is approx. as I have ignored densities etc).

 

If you decide to boil down the solution (reduce volume) the first thing to come out of solution will still be Sodium Chlorate.

 

If you must have solid Sodium Chlorate, keep adding Chloride solution as the cell progresses (you need some evaporation from the cell to allow this to happen) and Sodium Chlorate will start to appear on the cell bottom when the concentration of Chlorate gets high enough. A single quick wash in ice cold water (of this solid Sodium Chlorate) will get you Sodium Chlorate that will have just a small amout of Sodium Chloride still in it. It is quite difficult to get rid off ALL Chloride without multiple washing. (big pain in the arse).

 

It's the mutual solubility of the salts that you must look at if you want to see what, and how much of what, will come out of solution. Mutual solubilitys are a pain in the arse that most (if not all) Chlorate makers do not want to go near. So they poke around in the dark and hope for the best!! It easy with Potassium Chlorate as the K Chlorate just comes out of solution by itself as it's much less soluble that the K Chloride, as stated above.

Edited June 3, 2012 by frank

[WSM]

" If you use sodium chloride to make sodium chlorate, the resulting product is more soluble than the starting material. So separation is accomplished by concentrating the solution and lowering the temperature to the point where the chloride crystallizes out, leaving the more soluble chlorate in solution. I will leave it to your imagination (or further research) to determine for yourself how to best accomplish the concentrating and chilling methods required to separate the sodium chlorate from the sodium chloride. "

 

You will get no Sodium Chloride to come out of a solution that has been let run to (say approx.) 50 grams per liter Chloride (or even if only let run to 150grams per liter Chloride). If this said solution was started off with (approx.) 320 grams per liter Sodium Chloride then 270 grams (per liter) of the Chloride will have been converted into approx. 270 * 1.8 = 486 grams (per liter) Chlorate.

So you will have a solution that has about 50 grams per liter Chloride and 486 grams per liter Sodium Chlorate. Cooling might get you some Chlorate, but no Chloride will come out of solution. (the above is approx. as I have ignored densities etc).

If you decide to boil down the solution (reduce volume) the first thing to come out of solution will still be Sodium Chlorate.

If you must have solid Sodium Chlorate, keep adding Chloride solution as the cell progresses (you need some evaporation from the cell to allow this to happen) and Sodium Chlorate will start to appear on the cell bottom when the concentration of Chlorate gets high enough. A single quick wash in ice cold water (of this solid Sodium Chlorate) will get you Sodium Chlorate that will have just a small amout of Sodium Chloride still in it. It is quite difficult to get rid off ALL Chloride without multiple washing. (big pain in the arse).

It's the mutual solubility of the salts that you must look at if you want to see what, and how much of what, will come out of solution. Mutual solubilitys are a pain in the arse that most (if not all) Chlorate makers do not want to go near. So they poke around in the dark and hope for the best!! It easy with Potassium Chlorate as the K Chlorate just comes out of solution by itself as it's much less soluble that the K Chloride, as stated above.

 

Hi frank,

 

Thanks for your input.

 

If the sodium chlorate preferentially drops out of solution, then that's even better. I don't believe the chloride has to be totally gone before perchlorate will form (in a perchlorate cell), but most of it should be gone if you wish to preserve the platinum on your electrode. I haven't tried sodium salts yet, but I'm considering it. I posted my best guess by what I know (but my experience is primarily with potassium salts in chlorate cells).

 

So, if I understand you correctly, when you run a sodium chlorate cell and wish to extract sodium chlorate crystals, add concentrated sodium chloride solution and the chlorate will drop out as crystals, similar to the way chlorate crystals drop out in potassium cells? If so, it sounds like a good way to go.

 

WSM

[frank]

Hello WSM,

 

You said:

 

"So, if I understand you correctly, when you run a sodium chlorate cell and wish to extract sodium chlorate crystals, add concentrated sodium chloride solution and the chlorate will drop out as crystals, similar to the way chlorate crystals drop out in potassium cells? If so, it sounds like a good way to go."

 

 

I meant that you should keep adding concentrated Sodium Chloride (brine) solution to the Sodium Chlorate cell as it runs. Keep adding Chloride solution and keep running the cell.

(You need some evaporation happening for to allow this BTW). Eventually the solution becomes saturated with Sodium Chlorate at the running temperature of the cell (say around 40C) and then solid Sodium Chlorate starts to appear on the cell bottom. If you want you can stop the cell at that stage and cool and you will get more solid Sodium Chlorate but its best to just keep running and adding more Chloride solution. The Sodium Chloride concentration of the cell at this stage may be somewhere between 70 and 200 grams per liter. That's high enough to keep CE high. Sodium Chlorate will be in the region of 500 to 700 grams per liter.

This does not work too well in a one container type cell using Graphite anodes as the black stuff will be a bit of a nusience. It will work great with MMO.

 

You suggested adding concentrated Sodium Chloride (brine) to a solution of Sodium Chlorate in order to 'drop out' some Sodium Chlorate. This actually is done in the chemical industry but someone at home in the garage will not have any success using this method. It would be too hard to figure out how much Chlorate is in solution, how much Chloride to add etc etc. It works OK in a controlled set up using crystalizer running continously etc etc.

[Mumbles]

Crystallization will involve a mixture of both absolute and relative solubilities, as well as some energetics. Ignoring super saturation, there is only a finite amount of solid that can be dissolved at any given temperature. There is also a matter of relative solubility. There is going to be a differential of solubility between boiling and freezing. It's usually more soluble at higher temperatures, but there are some odd cases where things are less soluble in warmer water. In the case of sodium chloride and sodium chlorate, if you concentrate the cell liquor until solid starts forming, then cool it to near freezing, you will have primarily sodium chlorate precipitated. Sodium chloride has a very small change in solubility between freezing and boiling solutions. I bet two crystallizations would yield fairly clean sodium chlorate.

[WSM]

Hello WSM,

You said:

"So, if I understand you correctly, when you run a sodium chlorate cell and wish to extract sodium chlorate crystals, add concentrated sodium chloride solution and the chlorate will drop out as crystals, similar to the way chlorate crystals drop out in potassium cells? If so, it sounds like a good way to go."

I meant that you should keep adding concentrated Sodium Chloride (brine) solution to the Sodium Chlorate cell as it runs. Keep adding Chloride solution and keep running the cell.

(You need some evaporation happening for to allow this BTW). Eventually the solution becomes saturated with Sodium Chlorate at the running temperature of the cell (say around 40C) and then solid Sodium Chlorate starts to appear on the cell bottom. If you want you can stop the cell at that stage and cool and you will get more solid Sodium Chlorate but its best to just keep running and adding more Chloride solution. The Sodium Chloride concentration of the cell at this stage may be somewhere between 70 and 200 grams per liter. That's high enough to keep CE high. Sodium Chlorate will be in the region of 500 to 700 grams per liter.

This does not work too well in a one container type cell using Graphite anodes as the black stuff will be a bit of a nusience. It will work great with MMO.

You suggested adding concentrated Sodium Chloride (brine) to a solution of Sodium Chlorate in order to 'drop out' some Sodium Chlorate. This actually is done in the chemical industry but someone at home in the garage will not have any success using this method. It would be too hard to figure out how much Chlorate is in solution, how much Chloride to add etc etc. It works OK in a controlled set up using crystalizer running continously etc etc.

 

Hi frank,

 

I'm sure there is some evaporation at 40^oC, but certainly most of the water loss is due to being consumed in the process. Hydrogen bubbling off the cathode and oxygen bound to salts at the anode (and throughout the cell if bulk reactions are happening in a proper pH environment).

 

I need to know more about the sodium cells. Thanks for sharing your views and experiences.

 

WSM

[WSM]

Crystallization will involve a mixture of both absolute and relative solubilities, as well as some energetics. Ignoring super saturation, there is only a finite amount of solid that can be dissolved at any given temperature. There is also a matter of relative solubility. There is going to be a differential of solubility between boiling and freezing. It's usually more soluble at higher temperatures, but there are some odd cases where things are less soluble in warmer water. In the case of sodium chloride and sodium chlorate, if you concentrate the cell liquor until solid starts forming, then cool it to near freezing, you will have primarily sodium chlorate precipitated. Sodium chloride has a very small change in solubility between freezing and boiling solutions. I bet two crystallizations would yield fairly clean sodium chlorate.

 

I like it. Direct and to the point.

 

I'll have to give it a proper try when I get around to working with a sodium chlorate cell. Thanks, Mumbles.

 

WSM

[frank]

When a crystallization (allowing a warm/hot solution to cool) is performed from a Na Chlorate cell liquid containing low Chloride (below 100 grams per liter) and high Chlorate concentration, only Chlorate will come out of solution. All Chloride contamination comes from the solution sticking to / wetting the Chlorate crystals.

 

I had forgotton about water being used up by the cell reactions. For each 100 grams of sodium chlorate produced 50 grams (50cc) of water is used up (approx.).

This is not quite enough room for adding salt solution IMO. Evaporation is still needed. This leaves the maker with a dilema. If using a sealed cell, with just a small tube for gasses, you cannot get enough evaporation. If you take the lid off, you have the rusting-everything-in-sight mist going all over the garage. I suppose a large diameter tube going to outside is ideal.

 

Few people require solid Na Chlorate. Only if going to make Perchlorate I suppose using a platinum anode that they want to make last as long as possible.

 

Swede made K Perchlorate from K Chlorate directly and current efficiency was good. You will need larger volumes compared to Na, as solubilities are much lower.

[WSM]

When a crystallization (allowing a warm/hot solution to cool) is performed from a Na Chlorate cell liquid containing low Chloride (below 100 grams per liter) and high Chlorate concentration, only Chlorate will come out of solution. All Chloride contamination comes from the solution sticking to / wetting the Chlorate crystals.

I had forgotton about water being used up by the cell reactions. For each 100 grams of sodium chlorate produced 50 grams (50cc) of water is used up (approx.).

This is not quite enough room for adding salt solution IMO. Evaporation is still needed. This leaves the maker with a dilema. If using a sealed cell, with just a small tube for gasses, you cannot get enough evaporation. If you take the lid off, you have the rusting-everything-in-sight mist going all over the garage. I suppose a large diameter tube going to outside is ideal.

Few people require solid Na Chlorate. Only if going to make Perchlorate I suppose using a platinum anode that they want to make last as long as possible.

Swede made K Perchlorate from K Chlorate directly and current efficiency was good. You will need larger volumes compared to Na, as solubilities are much lower.

 

For system venting, I've opted for larger vinyl or silicone tubing (8mm-13mm). Nothing says you can't use rigid PVC pipe, but the soft vinyl or silicone is easier to deal with.

 

I was aware of Swede's work with potassium chlorate to perchlorate (and I appreciate him proving it's possible, even if industry doesn't do it this way). I like the idea of working sodium-free for end products intended for color star use, but the solubility issues concern me. I feel the perchlorate will drop out almost as fast as it's formed. That's good in that the crystals will be small, but I am concerned about crystal fouling of the cell. I wonder if the electrodes will get jammed or coated with crystals?

 

I don't know; I haven't tried it yet.

 

The one nice thing about using sodium salts is: the higher the oxidation state of the salt, the higher the solubility is. Once you process the perchlorate solution so it's free of chlorate, a simple(?) double exchange with KCl and you get the KP to drop out immediately. Then comes the purification to remove sodium and water. This is the way industry does it and I'm sure we can make a clean product this way, too.

I never said it was easy, I just said it was possible .

 

WSM

Edited June 7, 2012 by WSM

[Mumbles]

In my mind I always envisioned a buffer area of warmer water directly around the electrodes. The heat for the cell comes from the electrodes and resistance from the water. In an ideal situation the warm water directly around the electrodes would keep the perchlorate soluble until it diffuses away at which time it crashes out. An ideal situation is just that, ideal. It's hard to say if you'd get fouling or crystals blocking the electrodes. I'm not as familiar with the details of how all this works as the rest of you, but perhaps running at a more dilute concentration of chlorate could prevent excessive perchlorate crystallization near the electrodes.

[WSM]

In my mind I always envisioned a buffer area of warmer water directly around the electrodes. The heat for the cell comes from the electrodes and resistance from the water. In an ideal situation the warm water directly around the electrodes would keep the perchlorate soluble until it diffuses away at which time it crashes out. An ideal situation is just that, ideal. It's hard to say if you'd get fouling or crystals blocking the electrodes. I'm not as familiar with the details of how all this works as the rest of you, but perhaps running at a more dilute concentration of chlorate could prevent excessive perchlorate crystallization near the electrodes.

 

That's hard to say. Perhaps some experimentation is called for. The more dilute solution may help prevent crystal fouling but I think it would be harder on the electrodes (maybe; more thought is required). The idea of keeping the electrode area hotter would be facilitated by a vertical tube of compatible polymer material directly surrounding the electrodes (both together) and might work as you describe in the greater cell. I have a piece of PVDF tube about 90mm in diameter which would work well in such a situation. I may have to try it sometime. Thanks for the thoughts and suggestions.

 

WSM

[dangerousamateur]

Hmm OK.

 

Now lets assume I've got some chloride contaminated chlorate.

 

How would you normally check it for chloride?

What happens when you put silver nitrate into a chlorate solution? Anything like "silver chlorate"...?

[Potassiumchlorate]

Silver chlorate is probably like its other heavy metal relatives - rather explosive.

[dangerousamateur]

Well - that's what I thought... but will it form under normal conditions?

 

There must be some other way to test for chloride...?

 

 

 

And even if this is nothing someone with my level of experience should try but anyway, just interested:

When you make AP, and you recrystalize it, and so on - how do you dry this stuff?

[Arthur]

It's better to remove the chloride by washing the chlorate crystals with repeated small lots of water.

[Mumbles]

In solution it will all be a mixture of ions. If you happened to dry your test sample, it would remain as potassium chlorate and silver nitrate primarily. The equilibrium always favors the least soluble compounds for certain underlying chemical reasons. If there is chloride in the sample, then silver chloride will precipitate. If it doesn't then potassium chlorate is the next least soluble compound.

[WSM]

Most of my work on electrochemical cells has been on hold while we're remodeling the interior of our home (I don't dare to do hobby stuff if I want to sleep indoors when the home project is over )!!! BUT, I have been collecting various meters, thermal sensors and temperature controllers to use on an advanced system. It's exciting to learn about the availability of inexpensive alternatives to high priced name-brand scientific equipment which can be applied to our projects!

 

I was concerned about creating a "heat well" in my crystallizer chamber where the heater, pump intake (and submersible diaphragm pump), plus fluid level float switches will live. The need for a heat well becomes obvious if the pump inlet and control switches get fouled with crystals and cease functioning. With some of the new components I've acquired lately, I've overcome some of the last roadblocks to building and operating an effective and efficient continuous chlorate system . The final stage is building a securable structure to house such a unit (to keep others, not involved in the process, from contacting hazardous materials or conditions inside the structure). It needn't be more sophisticated than a small shed with power running to it, with a workbench and shelves inside. Running water is a plus but not strictly neccessary.

 

Any other ideas I should consider?

 

WSM

[pdfbq]

1339342887[/url]' post='96326']

Hmm OK.

 

Now lets assume I've got some chloride contaminated chlorate.

 

How would you normally check it for chloride?

What happens when you put silver nitrate into a chlorate solution? Anything like "silver chlorate"...?

 

I think (not know) that it is very difficult to remove *all* sodium chloride from sodium chlorate in an economic way. I dont think rekristalize will work due to the high soluabilities of both salts

 

Testing with silver nitrate shows the slightest trace of the Cl- ion. This means only ultra pure sodium chlorate shows no white precipitate. The only method i can think of making ultra clean chlorate is using silver nitrate to clean chemically your chlorate from the chloride and then rewin the silver with nitric acid or so.

Another way is let slowly evaporate a saturated solution of sodium chlorate. I grew beatifull big transparent christals that way. Rinse these with water then they must be pure but a slow method it is.

 

I assume you ask this question to make clean sodium chlorate to feed your perchlorate cell. I dont know if its worth all the trouble but it is certanly an interesting discussion.

I believe letting your perc cell run to long is much worse than a little chloride at the start. When run to long the pt changes color then, to gold/brown.

 

 

 

PS I am on holliday and my IPad makes a mess of the layout AND I dont have a spell checker. Sorry about this.

Edited June 16, 2012 by pdfbq