making potassium (per) chlorate

[WSM]

I've made some progress on the sodium chlorate experiment. I completed the preparation of my electrical distribution system to provide AC power to the power supply, pumps, lights, controllers and sensors.

 

The power supply weather shield is nearly finished and a shunt added to the negative output buss. The display panel with voltage/amperage and temperature meters is prepared and ready to connect to the cell.

 

I still need to test my brine for the presence of either calcium or magnesium. If either salt is present, I'll treat the brine to remove them and then proceed to run the system. My goal is pure sodium chlorate, and these steps are necessary to accomplish that goal.

 

More to come...

 

WSM

[MadMat]

Thanks for the benefits of your experience WSM. I wasn't too concerned if I got any perchlorate from this first trial. I just wanted to make sure the anode would perform and hold up. Was going to start up the cell yesterday, but got busy with other things. Hopefully, today is the day.

I really wish I had access to a SEM. That way I could tell for certain before running a cell if I had produced alpha or beta lead dioxide.

Edited May 6, 2016 by MadMat

[WSM]

Thanks for the benefits of your experience WSM. I wasn't too concerned if I got any perchlorate from this first trial. I just wanted to make sure the anode would perform and hold up. Was going to start up the cell yesterday, but got busy with other things. Hopefully, today is the day.

I really wish I had access to a SEM. That way I could tell for certain before running a cell if I had produced alpha or beta lead dioxide.

You're welcome.

 

Fair enough. Good luck with your research.

 

WSM

 

Edit: an SEM isn't necessary. 400x magnification should show enough detail to be useful, if I'm not mistaken.

Edited May 6, 2016 by WSM

[WSM]

I've made some progress on the sodium chlorate experiment. I completed the preparation of my electrical distribution system to provide AC power to the power supply, pumps, lights, controllers and sensors.

The power supply weather shield is nearly finished and a shunt added to the negative output buss. The display panel with voltage/amperage and temperature meters is prepared and ready to connect to the cell.

I still need to test my brine for the presence of either calcium or magnesium. If either salt is present, I'll treat the brine to remove them and then proceed to run the system. My goal is pure sodium chlorate, and these steps are necessary to accomplish that goal.

More to come...

WSM

 

Today I made good progress on the sodium system.

 

I finished the weatherization of the power supply and set it up on the shelf under the workbench (protected from rain or dripping electrolyte). I operated it and everything works as planned, with very little noise from the cooling fan.

 

I assembled the 2 AWG power cords and connected them to the electrode terminals and down to the power supply with enough extra length to make a drip loop.

 

 

I also connected the leads to the display panel plus secured the temperature sensor (previously sealed with Teflon shrink-tube to protect it from the mother liquor) in a sealed compression fitting in the lid, and running down to the middle of the electrolyte level in the RC. I powered the display and everything works, except there's no read from the ammeter till the current flows.

 

 

Everything is ready. Now I need to test the brine for calcium and magnesium to see if I need to take steps to remove them. If not, I'm ready to start it up !!!

 

I also plumbed a drain for the brine tank so I can move the brine to a purification process tank (if needed). It's all coming together and hopefully works without a hitch . We'll see...

 

 

WSM

Edited May 8, 2016 by WSM

[Arthur]

Have you decided on your target operating temperature for your cell?

 

IIRC Swede used water between "hot tap" and boiling hot to make a solution that was saturated at about 60C.

[WSM]

Have you decided on your target operating temperature for your cell?

IIRC Swede used water between "hot tap" and boiling hot to make a solution that was saturated at about 60C.

 

I haven't tried to control the cell temperature before, but just observe it. With this larger setup, I plan to just observe the temperature at the start. If the temperature level does something unusual (from what I expect), I'll visit the notion of controlling it. If the temperature settles somewhere reasonable, I'll monitor it but leave it alone.

 

I always make my electrolyte at room temperature, especially in bulk (this batch was 50 liters). I circulated the solution with a pump which did a good job and the solution is saturated at ambient temperature. Everything looks good so far.

 

I'll report here any problems and the changes made.

 

WSM

Edited May 8, 2016 by WSM

[WSM]

Last night I experimented with lighting the cell and it looks promising. I'm using some weather proof, white LED light strips designed for automotive use (daytime running lights) which run on 12 Vdc and 6 Watts, and are obnoxiously bright.

 

I placed the strip against the edge of the tank base (which is 1/2" [12.5 mm] thick, clear PVC sheet) and could clearly see the bottom of the tank illuminated. The clear PVC has a faint blue color added so the tank is lighted with a blue glow. I'm also considering placing one on the lid of the cell facing down, to illuminate it from above. The light strips are powered from a DC power supply plugged into a switched outlet so I can turn it on as needed and not run it continuously.

 

This is totally experimental. If I like it I'll continue to use it; if not, I'll abandon the idea.

 

WSM

Edited May 8, 2016 by WSM

[pyrojig]

WOW this section has moved forward since ive been away. Love the pics WSM. It seems like a very clean and simple setup .

As for Arthur : I remember trying a few things in the temp of the starting liqueur./ salt brine sol. I tried the hotest tap , with stirring to retain the max saturation. I found that on start up the temp dropped a little and the Kcl dropped out at the bottom of the cell, but was later taken into sol. when the temp went back up a little and some of the "super saturated " sol. was converted a few days later ., I was initially concerned that that there was going to be a cross-contamination of unreacted salt...., but after a cold wash /+ test at the end of the run, I was pleased with a nice yield and clean product. I second WSM on the just ambient / well circulated brine, for the sake of simplicity . I was only increasing the run time due to the extra salt in sol. but my C.E. did not really move to a positive #.

 

I believe that the cells temp will be dictated by many factors . Ea. change I made in the sys changed this temp range .

 

If the electrodes are too big , for the size of the cell and ran hard , over heating would result. too small of leads , bad connections , and hot summer days = overheating. I was pushing the bucket cell to the max bitter edge of 50-60C* , at one point I tested the Ti electrodes leads where the 10ga wire made contact . I found disturbing temp of 90C* Yikes!! It was starting to deform the kynar comp. fittings it passed through( i pulled the plug at this point till changes where made) . WSM suggested a constant current power supply( v.s. computer) , and increasing the leads to a larger size and filled .core.This would bring the resistance down and reduce wasted energy in heat form., while putting it back to the electrodes doing the work.

 

I too like the idea of a lit cell, to observe the level of salt buildup ( Kclo3 sys) , and watching for deteriorating electrodes if over driven ., I had to settle for a flashlight top lit BCA, but it did the trick cheap and quick.

[Arthur]

My basis for the high temperature approach was that when electrolysed and cooled something would ppt out and the liquor would be high in oxidised product and low in chloride, which is what we want. Then adding the low chloride liquor to the second cell should allow NaPerc to be made easily ready for salting out as KPerc.

[WSM]

My basis for the high temperature approach was that when electrolysed and cooled something would ppt out and the liquor would be high in oxidised product and low in chloride, which is what we want. Then adding the low chloride liquor to the second cell should allow NaPerc to be made easily ready for salting out as KPerc.

 

That is the fundamental Idea. After the sodium chlorate concentration is between 600 g. and 750 g. per liter, and the chloride level is as low as possible, we run the perchlorate cell.

 

When the perchlorate cell run is completed and we have sodium perchlorate solution, a key step is to destroy any residual chlorate before converting to potassium perchlorate by metathesis. If this step is left out, the potassium perchlorate will be contaminated with potassium chlorate.

 

If your perchlorates are tainted with chlorates, for safety's sake they should be treated and handled as chlorates.

 

It's also very important to wash all residual sodium contamination off the potassium perchlorate crystals before drying and storing them. Fortunately, potassium perchlorate has very low solubility compared to the sodium salts in the depleted liquor, and washing the KClO₄ is possible with low losses.

 

WSM

[Arthur]

At Na 23 and chlorine 35, and oxygen 16 (I'm not working to 6 dp!)

NaCl has Atomic mass 58

NaClO3 ----- 106

NaClO4 ...... 122

 

To get 750g of chlorate thats 750/106 moles =7.07moles which needs 7.07 moles of chloride which is 410 grammes so your solution must start with more than 410g of chloride in every litre which isn't going to happen (60C solubility 370g)

 

I read a text that said they topped up with hot saturated brine to add to the chloride as it is electrolysed.

 

interesting wiki https://en.wikipedia.org/wiki/Solubility_table#S

 

Same text said that the KCl addition was calculated to take out the amount of NaClO4 that had been made. Add KCl to perc heavy product KPerc drops out first, then if you add more KCl the KChlorate comes out, so if you add just too little KCl the precipitate should be all KPerc, just that you will be sending some NaPerc back to the first cell as cell make up solution with lots of NaCl.

 

If you cool a hot saturated chlorate liquor then the first to ppt out will be the NaCl.

[MadMat]

Well, my first attempt was, for lack of a better word, a failure. The anode held up O.K. but after somewhere between 45 minutes and one hour, the current dropped from 8.5 amps to less than .5 amps. I tried upping the voltage, but at reasonable voltages, I was getting no more than one amp. Just to test things out, I temporarily reversed the polarity, and immediately got 8.8 amps. Hmm, this is indicative of polarization of the anode. Visual inspection of the anode gave no clues as it looked completely unchanged. There were no signs of cracking/peeling of the coating. I might try a bit higher level of fluoride, but don't want to go over 400 ppm. Further research on the internet revealed a process that uses an alkaline solution to form the beta lead dioxide on the "massive lead anode". Back to the drawing board

 

Another thought I just had is maybe I need to adjust my cathode to anode surface area ratio. My test cell was slightly over a 4:1 cathode to anode ratio. Any thoughts on this WSM?

Edited May 11, 2016 by MadMat

[taiwanluthiers]

Is there a reason why no one sells lead dioxide anode? It looks like the setup required to make a workable one is complicated.

[WSM]

At Na 23 and chlorine 35, and oxygen 16 (I'm not working to 6 dp!)

NaCl has Atomic mass 58

NaClO3 ----- 106

NaClO4 ...... 122

To get 750g of chlorate thats 750/106 moles =7.07moles which needs 7.07 moles of chloride which is 410 grammes so your solution must start with more than 410g of chloride in every litre which isn't going to happen (60C solubility 370g)

I read a text that said they topped up with hot saturated brine to add to the chloride as it is electrolysed.

interesting wiki https://en.wikipedia.org/wiki/Solubility_table#S

Same text said that the KCl addition was calculated to take out the amount of NaClO4 that had been made. Add KCl to perc heavy product KPerc drops out first, then if you add more KCl the KChlorate comes out, so if you add just too little KCl the precipitate should be all KPerc, just that you will be sending some NaPerc back to the first cell as cell make up solution with lots of NaCl.

If you cool a hot saturated chlorate liquor then the first to ppt out will be the NaCl.

 

Thanks for the link to the solubility table. That is an excellent reference which I'll benefit from.

 

I understand where you're coming from. I don't plan to do the chloride to perchlorate as a straight shot, but plan to do the chloride to chlorate as the primary focus for the time being.

 

I'll see if I can concentrate the sodium chlorate, with multiple runs if I have to, till I can achieve as high a concentration as possible. After I manage to stockpile a reasonable amount of purified sodium chlorate, I'll move it to my perchlorate tests.

 

I have in the back of my mind the process you're referring to and may shift my direction to adopt that method more fully, but for now I'm taking "baby steps" and just getting started with sodium salts.

 

WSM

[WSM]

Well, my first attempt was, for lack of a better word, a failure. The anode held up O.K. but after somewhere between 45 minutes and one hour, the current dropped from 8.5 amps to less than .5 amps. I tried upping the voltage, but at reasonable voltages, I was getting no more than one amp. Just to test things out, I temporarily reversed the polarity, and immediately got 8.8 amps. Hmm, this is indicative of polarization of the anode. Visual inspection of the anode gave no clues as it looked completely unchanged. There were no signs of cracking/peeling of the coating. I might try a bit higher level of fluoride, but don't want to go over 400 ppm. Further research on the internet revealed a process that uses an alkaline solution to form the beta lead dioxide on the "massive lead anode". Back to the drawing board

Another thought I just had is maybe I need to adjust my cathode to anode surface area ratio. My test cell was slightly over a 4:1 cathode to anode ratio. Any thoughts on this WSM?

 

I'm sorry you ran into a roadblock with your research. I'm sure you're going to learn a lot about the whole process of anode making. We'll talk more about different approaches or modified procedures.

 

As for the electrode ratios, I usually go 1:1 unless there are over-riding reasons to skew the ratios one way or the other.

 

I'll give this some more thought and see if something else occurs to me later...

 

WSM

[WSM]

Is there a reason why no one sells lead dioxide anode? It looks like the setup required to make a workable one is complicated.

 

I believe most LD anodes we've seen for sale are from China and availability has been spotty. Yes, making them is not trivial.

 

WSM

[MadMat]

1:1? hmm, I have read a few things about (per)chlorate cells that have held true with electroplating as well. Current density at the anode (and cathode) is a very key parameter. Current density is what actually drives/regulates the electrochemical reactions. In a chlorate cell you want a higher current density at the anode. From what I've read, too high of a current density at the cathode and the precious chlorate (in the first stage anyways) can actually be reduced at the cathode back down to chloride. Am I missing something here?

[WSM]

Perhaps I should clarify my statement. Using a single anode, the most efficient starting point is two cathodes surrounding the anode.

 

If all the electrodes are the same size (matching), I feel they are in a good starting point.

 

More properly, a 2:1 ratio of cathodes to anode (I misspoke in my last post).

 

If other wisdom exists to suggest otherwise, I'm willing to hear it and learn.

 

WSM

[MadMat]

Well, that sounds like it makes sense. Maybe my problem came about because of a bad anode to cathode surface area ratio. I know in chrome plating, running the bath with too high of a cathode to anode ratio will produce trivalent chrome contamination and possible polarization of the anodes; this occurs especially when plating internal diameters as the part surface area is much larger than that of the anode. Of course, in a plating bath the electrochemical reaction is the opposite of a chlorate cell.

 

I'm going to remake my anode and re-run the experiment with a 2:1 ratio and see what happens

Edited May 11, 2016 by MadMat

[WSM]

I dont know about plating, but most of the perchlorate information I've read suggests using beta form LD rather than alpha.

 

It's something about the electrical properties and/or the physical/chemical nature of the crystalline surface working better and lasting longer in the cell.

 

I don't want to discourage you from trying it with the alpha form LD, but it probably would work better, longer and without as much trouble. I believe Swede came to that conclusion before he made his own LD anode.

 

For what it's worth...

 

WSM

Edited May 11, 2016 by WSM

[MadMat]

I am trying for an electrochemical process that produces beta lead dioxide. I just had the idea that maybe a combination of the two forms might work as beta is rather brittle (as stated earlier, massive lead anodes (as they are called) can run into problems if the outer coating cracks and peels off.) So, what I am working on is a way to make the massive lead anode a viable working anode

[WSM]

I am trying for an electrochemical process that produces beta lead dioxide. I just had the idea that maybe a combination of the two forms might work as beta is rather brittle (as stated earlier, massive lead anodes (as they are called) can run into problems if the outer coating cracks and peels off.) So, what I am working on is a way to make the massive lead anode a viable working anode

Beta form lead dioxide IS brittle, but if it's on a solid foundation (CP titanium or graphite) it would be properly supported, and if you avoid physical damage to it, it should be fine.

 

WSM

[memo]

my cell has about 48 hours run time and the water is turning yellow. the salt I bought said it was 100 % food grade salt, this is salt that is used for swimming pools. I was reading the fine print and the only thing that was not normal is it said it was enhanced salt. nothing about what it is enhanced with. is that going to cause a problem ? it is only a 3 liter cell.

 

memo

 

[WSM]

my cell has about 48 hours run time and the water is turning yellow. the salt I bought said it was 100 % food grade salt, this is salt that is used for swimming pools. I was reading the fine print and the only thing that was not normal is it said it was enhanced salt. nothing about what it is enhanced with. is that going to cause a problem ? it is only a 3 liter cell.

memo

 

Hi memo,

 

You say the salt is listed as food grade? Food grade salt often includes sodium ferrocyanide as a free flow agent (also known as yellow prussiate of soda). The yellow color might be due to the iron content of the additive?! Another common additive with food grade salt is an iodide, which might also create a yellow color if minute amounts of free iodine were released, I'm guessing.

 

Salt for swimming pools shouldn't have any additives added, but I'm guessing in this case, also.

 

I don't have more to go on than your description.

 

WSM

 

Edit: Another thought, as the chloride turns to chlorate, the electrolyte (full of hypochlorite, hypochlorous acid and dissolved chlorate) tends to turn a faint yellow-green color. If your electrolyte smells strongly of bleach and the color is very faint, - everything is normal and there's nothing to worry about.

 

If the yellow color you describe is strong or deep in tone, there's a problem.

Edited May 12, 2016 by WSM

[memo]

the color was bothering me. I used bolts that were plated gold color they hold the connections to the top. they are the bolts that hold your toilet to the floor. there is no yellow left on them.

I think that is where the yellow is coming from.

on the salt the only thing out of the ordinary was the words that said enhanced. the yellow is light colored.

 

memo