making potassium (per) chlorate

[THEONE]

Yes but if i understand correct from mumbles, Ph is much more responsible for a good effciency than temp.

[barzn]

Barzn - I'm pleased that you have solved the problem. Electrolysis at a higher temperature is beneficial, so maybe you could stand the cell in a draught free place or even insulate it a little, when you have done a complete run, you will know how the temperature changes with current and time.

Thank you. As i mentioned, i will maintain the temperature between a desirable range (~65c for the MMO cell, lower for the Pt and LD, ~35c and ~45c accordingly), and also the pH at about 6-6.5. I do aim to get the highest CE that i can implement with my resources.. i will also monitor and log this parameters periodicly to observe and estimate the changes during a cell's run. (which will help estimating the CE and amount of product produced over a certain time..)

 

The photos from the power supply seller looked like the power leads had very small wires. I suppose that's why several of us suggested stepping up to larger gage wires. I, too, am glad it worked out for you. Congratulations.

WSM

hehe, You are so right. It's funny how i didn't notice that.. much appreciate your help!

 

Hi barzn,

My Pt and LD setups were "proof-of-concept" cells. I ran them with reagent grade sodium chlorate with a concentration of 600 grams per liter of distilled water.

Between the two, I'm most pleased and impressed with the LD anode. From my research, I expected better performance from LD over the Pt, but it ran even better than I expected it would. I'm not sure if the higher quality feed stock made the difference or was it the carefully controlled lower current density.

I need to set up a sodium chlorate cell (I've only run potassium chlorate before the sodium perchlorate cells) to make feed stock for the perchlorate cells, and compare runs with it to the reagent grade material. I'm running these experiments to expand the body of knowledge (and share it here), plus try to get to the point where we can make our own pyrotechnics grade potassium perchlorate from scratch. I love the sense of self sufficiency, making my own materials gives.

If you have any specific questions, feel free to ask here or send a PM. Your choice.

WSM

That's a great bonus to have a reagent grade chlorate starting material, getting good enough NaClO3 can be tricky, so good for you! And i, as you, love the excitment of being able to make our own (importantly pyro grade) chlorates and perchlorates, even if they were freely available. More than that, obtaining those in my country is not an easy task (i'd say far more than making it), and they would also cost alot, far more than in the US and elsewhere - but thats not the reason i've decided making it in my own. It's nice to see how much homemade proccess like that can get close to industry's quality, and to keep on improving ourselves for that end.

 

It's very interesting to see that the LD performed far better for you than the Pt did. when we discussed that in theory, i expected similar results, or the LD being slightly better (It's also being suggested in many experiment's papers). I really wonder if i'll have simillar results. we'll see

What is the substrate of the anodes that you used? did you made your own LD?

My chinese made TSLD suprised me with it's quality (in relation to the price), it was very heavy and very well and thick coated, the Platinized Ti seems much less thick coated, but thats reasonable, and makes sense.. maybe that's why one would prefer going with the LD..

it's getting more and more interesting.. thanks to everyone here..

 

And again, thank you very much for the information and kind support!

Edited April 23, 2015 by barzn

[WSM]

It's very interesting to see that the LD performed far better for you than the Pt did. when we discussed that in theory, i expected similar results, or the LD being slightly better (It's also being suggested in many experiment's papers). I really wonder if i'll have simillar results. we'll see

What is the substrate of the anodes that you used? did you made your own LD?

My chinese made TSLD suprised me with it's quality (in relation to the price), it was very heavy and very well and thick coated, the Platinized Ti seems much less thick coated, but thats reasonable, and makes sense.. maybe that's why one would prefer going with the LD..

it's getting more and more interesting.. thanks to everyone here..

And again, thank you very much for the information and kind support!

 

Hi barzn,

 

The substrate of almost all of my anodes is titanium (I do have the odd one where platinum is plated on niobium wire with a heavy copper core, but I've done nothing with it yet).

 

No, I bought my LD anodes. The original source is China, but I bought mine from people in the US who bought them from the Chinese distributers.

 

Edit: I did cut off the power strap and spot weld filled, tubular titanium leads to the anodes and cathodes, so I could secure them in PVDF compression fittings (in an attempt to limit, if not stop, salt creep).

 

Good luck with your research.

 

WSM

Edited April 23, 2015 by WSM

[Mumbles]

Yes but if i understand correct from mumbles, Ph is much more responsible for a good effciency than temp.

 

My understanding is that pH is more important than temperature. Without pH control, you max out at 66% efficiency I believe. For what it is worth, I'm talking about current efficiency, not actual potential product yields. I don't think this is necessarily because the temperature isn't important. More that at common cell temperatures (40-80C for instance), the limiting factor is the hypochlorite production at the anode. You're basically decomposing hypochlorite as fast as it's being produced. If you're already at the rate limit at 50C, increasing to 80C isn't going to make any difference. This is largely true at pH controlled conditions.

 

In uncontrolled pH situations, the pH will rise dramatically due to the production of NaOH. Hypochlorite is more stable at more basic pH. In this case, you lose some current efficiency. If hypochlorite is stable enough to hang around for a while, it will start to be oxidized by the anode, instead of just doing it's favored decomposition to chlorate. This uses up electrons that could be used to oxidize chloride instead. Even at high temperatures in basic conditions, the decomposition is not instantaneous and will not go to completion anyway.

 

If you want high efficiency, you're better off controlling the pH, even crudely, than worrying about pumping up the temperature.

[schroedinger]

Alsona problem to kenti8nnwith the temperature is that many available anodes aren't rated for those high temperatures. LD likes to fail if used at above 80ºC (at 60 ºC you can allready easly measure that they last not os long as if used at lower temperatures

.) some MMO have the same problems too.

[WSM]

Thank you. As i mentioned, i will maintain the temperature between a desirable range (~65c for the MMO cell, lower for the Pt and LD, ~35c and ~45c accordingly), and also the pH at about 6-6.5. I do aim to get the highest CE that i can implement with my resources.. i will also monitor and log this parameters periodicly to observe and estimate the changes during a cell's run. (which will help estimating the CE and amount of product produced over a certain time..)

 

hehe, You are so right. It's funny how i didn't notice that.. much appreciate your help!

 

That's a great bonus to have a reagent grade chlorate starting material, getting good enough NaClO3 can be tricky, so good for you! And i, as you, love the excitment of being able to make our own (importantly pyro grade) chlorates and perchlorates, even if they were freely available. More than that, obtaining those in my country is not an easy task (i'd say far more than making it), and they would also cost alot, far more than in the US and elsewhere - but thats not the reason i've decided making it in my own. It's nice to see how much homemade proccess like that can get close to industry's quality, and to keep on improving ourselves for that end.

 

It's very interesting to see that the LD performed far better for you than the Pt did. when we discussed that in theory, i expected similar results, or the LD being slightly better (It's also being suggested in many experiment's papers). I really wonder if i'll have simillar results. we'll see

What is the substrate of the anodes that you used? did you made your own LD?

My chinese made TSLD suprised me with it's quality (in relation to the price), it was very heavy and very well and thick coated, the Platinized Ti seems much less thick coated, but thats reasonable, and makes sense.. maybe that's why one would prefer going with the LD..

it's getting more and more interesting.. thanks to everyone here..

 

And again, thank you very much for the information and kind support!

 

I would say Mumbles hit it on the mark.

 

For chlorate cells, an average temperature between 50^oC and 55^oC has worked well for me. That said, I never tried to control the temperature; I just let it happen (I observe or monitor it but don't get overly concerned about it unless it goes far out of normal range). The temperature rise in chlor-alkali cells is due to electrical resistance (inefficiencies) in the cell, which manifests itself as heat. The heat is not (totally) wasted since it improves the CE slightly.

 

As for pH, the ideal for chlorate cells is 6.8* (or as close as you can get to it). In practice, anything in the range of 6.5-7.0 can be considered correct. I recommend avoiding anything at 6.0 or below, where the chlorate cell will start pumping out free chlorine. As for the pH in perchlorate cells, the jury is still out. There is debate for control and against control. I haven't seen anything yet that convinces me it's essential for perchlorate cells.

 

*Edit: at (or near) a pH of 6.8 the optimal conditions exist where a 2:1 ratio of HOCl^- to OCl^- is maintained, and generates ClO3^- with the least consumption of current and side reactions (which delay the producion of chlorates), i.e., more chlorate and faster with less power.

 

My use of reagent grade material was to eliminate as many unknowns as possible from my experiments. Now that I've used up my meager supply, I'm forced to make my own, and I'll compare everything I do from here on, to the reagent grade material. We'll see how it goes...

 

WSM

Edited April 24, 2015 by WSM

[WSM]

Alsona problem to kenti8nnwith the temperature is that many available anodes aren't rated for those high temperatures. LD likes to fail if used at above 80ºC (at 60 ºC you can allready easly measure that they last not os long as if used at lower temperatures

.) some MMO have the same problems too.

 

The ruthenium-iridium MMO should handle quite diverse conditions (including short term high temperatures), but abusing it with extreme environments is not advised, if you want longevity for your electrodes.

 

WSM

[THEONE]

Is out there any easy way to keep rhe Ph at a such rate for best efficience ? Somewere i read that there is a way to control it if you only know your Amperehours.

[Arthur]

pH control means more than just amp hour counting sadly. BUT if you count amp hours and add acid, you will need smaller top-ups manually and less use of pH paper. The challenge is that pH electrodes are eaten away by the electrolyte so they only stand a few uses before they are finished.

 

This thread has a brief discourse on pH control by amp hour counting, and someone offered to develop a PIC based controller.

[THEONE]

It is not necessary to boil a sample from electrolyte before you check the Ph, to destroy the hypochlorite ?

[WSM]

Is out there any easy way to keep rhe Ph at a such rate for best efficience ? Somewere i read that there is a way to control it if you only know your Amperehours.

 

Swede offered:

 

0.057 ml of concentrated (32%) HCl per ampere, per hour, with the HCl delivery cut by 33% after the chlorate crystals begin to form.

 

I believe he got the information from science madness.

 

You can dilute the acid with distilled water but should increase the volume to get the same concentration of acid into the electrolyte (if you dilute the acid to one fourth the full strength, multiply the volume by four to get the right amount).

 

WSM

Edited April 25, 2015 by WSM

[WSM]

It is not necessary to boil a sample from electrolyte before you check the Ph, to destroy the hypochlorite ?

 

No, just use a bit of pH paper but watch it closely because the chlorate electrolyte bleaches out the pH reagent.

 

WSM

[THEONE]

 

Swede offered:

 

0.057 ml of concentrated (32%) HCl per ampere, per hour, with the HCl delivery cut by 33% after the chlorate crystals begin to form.

 

I believe he got the information from science madness.

 

You can dilute the acid with distilled water but should increase the volume to get the same concentration of acid into the electrolyte (if you dilute the acid to one fourth the full strength, multiply the volume by four to get the right amount).

 

WSM

This is for pottasium i bet, for sodium is the same ?

 

And also it is not possible to combine these two informations (before and after the chlorate crystals begin to form) to make one simpler rule ?

Edited April 25, 2015 by THEONE

[WSM]

This is for pottasium i bet, for sodium is the same ?

And also it is not possible to combine these two informations (before and after the chlorate crystals begin to form) to make one simpler rule ?

 

It should be the same for sodium, but closer pH monitoring should be used with a sodium chlorate cell because of the solubility differences between sodium and potassium cells.

 

Using this technique requires careful monitoring of the pH because the amount of acid needed reduces as the cell runs. I believe the cell reaches an equilibrium at some point where no more acid is required to maintain the highest efficiency.

 

I suppose, with an automatic acid injection system, you could start with a lower amount and keep the doses at the same level throughout the run, but that way your pH would be higher (alkaline) than desired to start and slowly drift to lower (acid) than desired toward the end of the run. The hazard would be chlorine generation during the latter half of the run if the pH drops to below 6.0.

 

WSM

[WSM]

It is not necessary to boil a sample from electrolyte before you check the Ph, to destroy the hypochlorite ?

 

If you take the time and read though Swede's blogs, and follow his experiences, you'll have a better understanding of the processes and techniques that have brought us to the point we're at now. Swede kept his blogs as a type of online lab notebook, and they're a valuable resource for us to use.

 

WSM

[WSM]

I've finished and submitted for publication in the PGI Bulletin, part nine of my series on homegrown oxidizers. It's showing some details of my two experimental perchlorate cells, and proving the concept works.

 

If you're a PGI member, look for it in the next few months (and comment here when you see it, Thanks).

 

WSM

[THEONE]

 

If you take the time and read though Swede's blogs, and follow his experiences, you'll have a better understanding of the processes and techniques that have brought us to the point we're at now. Swede kept his blogs as a type of online lab notebook, and they're a valuable resource for us to use.

 

WSM

Those informations are somewere here splited, and i have to find them, or they are somewere all together ?

[WSM]

Those informations are somewere here splited, and i have to find them, or they are somewere all together ?

They're here in the blogs titled "You'll shoot your eye out".

 

WSM

Edited April 26, 2015 by WSM

[frank]

Read this page too

 

http://oxidizing.typhoonguitars.com/

[WSM]

Read this page too

 

http://oxidizing.typhoonguitars.com/

 

I agree, read through them both. There's a lot of information in these two sources; in fact printing them both and binding them in loose-leaf notebooks would be a valuable (and HUGE) resource.

 

Thanks, frank.

 

WSM

[pyrojig]

Wsm....

I got to thinking , and something we talked about struck a idea. I know that the process of making Naclo3 to go to Naclo4 could indeed have Nacl impurities in it if not addressed. ,,,,But that is where I got to thinking ....... Is NaCl impurities a danger to LD as it is to Platinum ? Will it cause the LD to degrade or will LD be more impervious to the residual salt? If So, That offers lots of steps removed from the process, and the cost and labor reduced. I know that the salting out process should drop out Kclo4 and the more soluble ( NaCl and NaClo3/ 4) will stay in sol. Just a thought. It seems that industry does the process continuous and , they wouldn't go to any more steps than needed to obtain the preferred salt ( kclo4).

[Arthur]

The piece I read stated that industry uses sodium salts for their solubility, their starting liquor was about 600g/l with sodium salts, the max achievable with K salts is about 300g/l.

Edited May 1, 2015 by Arthur

[WSM]

The piece I read stated that industry uses sodium salts for their solubility, their starting liquor was about 600g/l with sodium salts, the max achievable with K salts is about 300g/l.

 

Yes, depending on temperature.

 

Higher temperatures will typically increase the amount of salt able to dissolve (but don't over do it*). Chemists often regard solubility at STP, i.e., standard temperature and pressure (25^oC at 1 atmosphere, for example).

 

edit: *Better to avoid too much heating of the solution and "super saturating" it, risking having the precursor salt crash out as a mass of crystals before it can work as intended in the perchlorate cell.

 

WSM

Edited May 4, 2015 by WSM

[WSM]

Go for the double replacement method, it is the only way that is safe.

Distillation of perchloric acid isn't worth the hassle.

An other idia i have, but I'm not sure if it would work.

Maybe if you take the sodium perchlorate, dissolve it and combine it the solution with a solution of oxalic acid.

Sodium oxlate is close to insoluble and if you use two solutions the acid would be quite diluted , use about 0.1-0.5 % exes of oxalic acid.

Imeaditly submerge the cake in a solution of ammonia carbonate to remove all of the free acid.

Now filter of the precipate through glass wool and add barium carbonate until no precipate is formed to remove the excess oxalic acid.

Now add ammonia carbonate or hydroxide to precipate the AP.

Maybe it is worth a test, but I do not know if this route will work or not. Also limit the perchloric acid content to a max of 25% should be a good idea. Watch out perchloric acid is no joke and I'm not sure what it can do to the organic oxalate.

 

After re-reading this post, another possibility along these lines occured to me:

If, rather than oxalic acid, a solution of ammonium oxalate were added to sodium perchlorate solution, the sodium oxalate would drop out (removed by filtration plus cleaned and saved for future use) and the ammonium perchlorate could be recovered from the filtrate.

 

If you have access to oxalic acid but not ammonium oxalate, neutralization of the acid with ammonium hydroxide (aqueous ammonia) should be all that's required to obtain some to use.

 

By this means (and careful attention to detail), a win-win situation may exist (making AP with sodium oxalate as a by-product) !

 

WSM

Edited May 4, 2015 by WSM

[WSM]

Wsm....

I got to thinking , and something we talked about struck a idea. I know that the process of making Naclo3 to go to Naclo4 could indeed have Nacl impurities in it if not addressed. ,,,,But that is where I got to thinking ....... Is NaCl impurities a danger to LD as it is to Platinum ? Will it cause the LD to degrade or will LD be more impervious to the residual salt? If So, That offers lots of steps removed from the process, and the cost and labor reduced. I know that the salting out process should drop out Kclo4 and the more soluble ( NaCl and NaClo3/ 4) will stay in sol. Just a thought. It seems that industry does the process continuous and , they wouldn't go to any more steps than needed to obtain the preferred salt ( kclo4).

 

This appears to be sound reasoning, and I've tried to remember what I've read in so many reports about commercial sodium perchlorate operations, and the purity of their sodium chlorate feed stock.

 

Without solid evidence to back my suspicions, let me say that my gut feeling is that there are less ill affects from residual chloride in the sodium chlorate (in an LD based perchlorate cell); but if we can produce chloride-free chlorate, we should and it'll be better for the system, overall.

 

I'm still learning as I go; let's see where all this takes us...

 

WSM