making potassium (per) chlorate

[WSM]

I like where these discussions are going. Please contribute any relavent data you may have, to add to the body of knowledge presented here, BUT please keep it accurate and detailed enough that others can easily follow what you're doing or describing (otherwise what use is it?!).

 

Thanks.

 

WSM

Edited January 13, 2015 by WSM

[WSM]

Does anyone have a good circuit design for an amp/hour controller?

WSM

 

I posed this question in the Electronics Section, and it appears to be generating some discussion on the feasiblity of such a system to control the pH of our cells.

 

If this pans out and proves to be reasonably easy to do, a major hurdle to simplified pH control may be just around the corner! Let's see what comes of all this. I'm hopeful all this is fruitful.

 

WSM

Edited January 15, 2015 by WSM

[schroedinger]

Shouldn't it you be able to build an easy amp controll device by putting the cell in series with an nirmal light bulb. This way you limit the max amperes.

[WSM]

Shouldn't it you be able to build an easy amp controll device by putting the cell in series with an nirmal light bulb. This way you limit the max amperes.

 

I'm not trying to limit the maximum amperes.

 

I'm looking for an Amp-Hour Controller which will switch on a pump at intervals (determined by the current flow for a given time period) to dose the chlorate cell with dilute hydrochloric acid to control the pH of the cell.

 

WSM

[Arthur]

For a cell run to the amp hours required for (100%CE) stoichemetric end point could you use the amphour counter to warn the operator when the end point is approaching.

 

What would happen if you took a chlorate cell and ran it close to completion then with a bellows pump added more saturated chloride solution, and collected the overflow, This overflow solution would be heavy with chlorate and ripe for either making into perc cell feedstock or harvesting the chlorate continually.

[WSM]

For a cell run to the amp hours required for (100%CE) stoichemetric end point could you use the amphour counter to warn the operator when the end point is approaching.

What would happen if you took a chlorate cell and ran it close to completion then with a bellows pump added more saturated chloride solution, and collected the overflow, This overflow solution would be heavy with chlorate and ripe for either making into perc cell feedstock or harvesting the chlorate continually.

 

I believe Swede addressed the notion of running a chlorate cell to completion in his blogs or other notes. His conclusion was there is a point of diminishing returns where it's best to stop before going much lower than 8% (or was it 6%) chloride, so as to avoid running the system much longer for very little gain in chlorate production. He would stop, recharge the electrolyte, and start the next run; realizing much greater yields by not running the cell to completion.

 

Another point to note; the best conditions for a perchlorate cell include very low to no chlorides in the cell, which are hard on LD or platinum anodes. Purifying raw chlorate feed stock to eliminate any chloride contamination should go a long way in preserving the perchlorate anodes, ensuring their longevity.

 

Also, as Arthur already mentioned, keeping the feed stock concentrations high should be easier on the perchlorate anodes, as well.

 

WSM

[Arthur]

I'm assuming that with the aid of the amphour count the stoichemetric theoretical end point is a number on a counter, BUT I'm accepting that we would never pass 90% current efficiency, so, the "completion" amphour count really means about 10% remaining chloride.

[WSM]

I'm assuming that with the aid of the amphour count the stoichemetric theoretical end point is a number on a counter, BUT I'm accepting that we would never pass 90% current efficiency, so, the "completion" amphour count really means about 10% remaining chloride.

 

Or 8%, or 6%; whatever we decide our cut-off point should be. Of course, this is for batch systems; I believe continuous systems would follow some different rules.

 

With a continuous potassium chlorate system, for example, the KClO₃ drops out of solution in the crystallizing chamber, while fresh chloride is added to the reaction chamber as the system runs. In a continuous sodium chlorate system, the solubilities of the different dissolved salts won't work the same as in the potassium system. I'll have to think through the details of a sodium system more...

 

WSM

Edited January 17, 2015 by WSM

[Arthur]

If you take a cell, loaded with chloride and electrolyse it to 100% theoretical current requirement you should have about about 10% of the chloride remaining due to the current efficiency of the system.

You could then either;

use this as a batch,

OR

pump in more hot saturated chloride solution and collect the overflow

[WSM]

If you take a cell, loaded with chloride and electrolyse it to 100% theoretical current requirement you should have about about 10% of the chloride remaining due to the current efficiency of the system.

You could then either;

use this as a batch,

OR

pump in more hot saturated chloride solution and collect the overflow

 

In a sodium chlorate cell, do you suppose there's a point where adding more chloride solution will drop out the sodium chlorate? If so, and the solubilities alone don't indicate this, then there are details of the process I'm not aware of.

 

Anyone here make a lot of sodium chlorate and can share more information about it?

 

WSM

[WSM]

After some thought, going by the solubility of the different salts, one method to separate sodium chloride from sodium chlorate (both in solution) would be to cool the electrolyte to the point where the chloride crystallizes out, leaving the chlorate in solution.

 

Does this make sense in practice or are other methods more practical?

 

WSM

Edited January 17, 2015 by WSM

[Arthur]

If you have a (slow) flow through a cell then it will never get to completion because some incoming chloride will always be there and some largely completely electrolysed product will always be leaving as overflow to purification.

 

Imagine a tank say 12" by 1" surface and about 8" deep, electrolyte say 7" deep with two electrodes about 8 x 5 inches and say 1/4" apart. Current say 50A.

This would get hot while electrolysing it's small content so we clad it with another tank with just salt and pure water. Then pump (iwaki bellows) the chloride solution (hot saturated) into the cell at one end and let the cell overflow at the other end into a cooler. What crystalises will depend on the cation but you will have a continuous supply of chlorate til the power goes off.

[WSM]

5" x 8"?!! Wow, that will take up to 154.8 Amps!

If your power supply can limit the output to 50 Amps without overheating, the system should last a long time (barring any mishaps). Considering the heat output of such a cell, I'd recommend making the tank from CPVC, if made from a polymer, so it could handle the heat.

WSM

Edited January 17, 2015 by WSM

[WSM]

If you have a (slow) flow through a cell then it will never get to completion because some incoming chloride will always be there and some largely completely electrolysed product will always be leaving as overflow to purification.

Imagine a tank say 12" by 1" surface and about 8" deep, electrolyte say 7" deep with two electrodes about 8 x 5 inches and say 1/4" apart. Current say 50A.

This would get hot while electrolysing it's small content so we clad it with another tank with just salt and pure water. Then pump (iwaki bellows) the chloride solution (hot saturated) into the cell at one end and let the cell overflow at the other end into a cooler. What crystalises will depend on the cation but you will have a continuous supply of chlorate til the power goes off.

 

It sounds like a solid basis for a continuous chlorate cell. One option might be to make the cell of TIG welded, CP titanium and use the tank for the cathodes. Spacers between the anode mesh and cathodes could be ceramic, glass, compatible polymer or elastomer, et cetera; to keep an even distance between the electrodes. Keeping the vertical channels in the cell open will promote good circulation plus venting of hydrogen or other gasses.

 

To prevent crystal jamming, bonding the outer walls of such a cell with PVC (or CPVC) foam or fiberglass matting would help to keep the heat in or the cool ambient temperatures out. In fact, all the fluid tanks and connections up to, but not including, the crystallizer might well be insulated in such a fashion, to promote proper operation of such a continuous system.

 

Well done, Arthur. Do you plan to build such a setup, or are you just considering it?

 

WSM

[WSM]

Oh, I forgot to mention; for a crystallizer tank, long, wide and shallow will have a lot of surface area (for cooling) and not have enough head pressure (depth) to require overly-strong construction. Such a tank could be made from PVC sheet and be shaped somewhat like a rectangular tub or tray. A friend of mine (who runs a continuous system) cautions, beware of strong chlorine (hypochlorite) fumes when harvesting from such a crystallizer.

 

Negative airflow venting with large bore pipe or vacuum tubing would help to minimize such an alarming experience.

 

When setting up or planning a continuous system, there are many details to consider.

 

WSM

[Arthur]

The issue that has vexed me for a while is how to pump hot saturated brine into the tank (the iwaki bellows should hold 50C) then I thought of cladding the whole thin cell in another tank containing the brine, so the brine supply is hot, ready to feed into the tank.

 

I always thought of blowing air over the PSU for cooling then ducting that air as the drive for a venturi to suck surplus air/hydrogen/fumes/spray out of the cell and maybe into a cyclone separator. -I don't want my plants dying of fumes to indicate where the chemical plant is.

 

If I could work it out there must be a continuous perc system too. Steady drips of chlorate laden overflow run into the next cell with a Pt electrode and hot perc solution runs out the end. Something tells me that it's three times the current to make a mole of chloride into chlorate than to turn a mole of chlorate into Perc.

 

The next issue is whether it's worth going auto when 10kilos of perc is a year's worth of hobby use. 10k of perc would likely come from two runs of 20litres, so after a week of electrolysis you could clean the kit and store it for 50weeks

Edited January 17, 2015 by Arthur

[WSM]

Good points. I'm not in any particular hurry to finish my continuous systems because the needs aren't there (just the wants). So I plod along in my research and occasionally make rapid strides when things line up properly.

 

My thoughts about fume and vapor removal are along the lines of a larger bore PVC drainage wye with the straight section vertical and the side tube coming up and into the vertical; placing a muffin fan in the side tube pointing upward to create slight vacuum and an upward draft, without being in the direct line of vapor flow (hopefully also not close enough to cause sparks or ignite hydrogen flowing upward off the system).

 

Commercial concerns run their perchlorate setups as continuous systems (sodium), and I don't see why we couldn't also, but on a small scale of course.

 

To handle hot solutions, my method involves a home made PVDF and Viton submersible diaphragm pump (shown in part 5 of my Homegrown Oxidizers series; the next blog entry to be submitted hopefully soon). The diaphragm pump is powered by an aquarium air pump controlled by an electronic timer kit to set pumping frequency and duration. The only problem I can forsee with it is possibly needing to preheat the air before running it to the pump, to prevent crystal fouling of the pump.

 

WSM

[Ubehage]

I am wondering about the rinsing of the final product: Is there any safe way to determine, if you have "pure enough" perch?

And if it's not pure, is there a way to test this?

 

I am ignorant, and therefor afraid, of chlorate.

[pyrojig]

If you follow the previous notings in this thread your going to find that answer. The use of Agno3 and Methylene blue the most common reagents to determine the lack of chlorate / and chloride in the finish products.

Allan Yates uses a 0.3% solution of Methylene Blue and a 0.1% solution of Indigo Carmine ( for for testing for residual chlorates in the final perch)

 

Dont fear chlorates , but more so respecting them for their idiosyncrasy's is a better approach. They offer lots of benefits other oxidizers cant. Research is the best way to understand the material , v.s. avoiding it altogether .

Edited January 23, 2015 by pyrojig

[WSM]

I am wondering about the rinsing of the final product: Is there any safe way to determine, if you have "pure enough" perch?

And if it's not pure, is there a way to test this?

 

I am ignorant, and therefor afraid, of chlorate.

 

Methylene blue solution will test for perchlorate, even in the presence of nitrate and/or chlorate. Indigo Carmine solution will test for chlorate and is very sensitive. In combination with sodium sulfite solution, indigo carmine solution is the most sensitive test for chlorate plus isn't as toxic or expensive as some other options (aniline HCl or N-Phenylanthranilic Acid).

 

A drop of test solution (sample salt dissolved in distilled water) is added to a drop or two of indigo solution and sodium sulfite solution (previously mixed) in a spot plate or test tube. If the dark blue color dissappears, chlorate is present.

 

Mix the reagents freshly, just before testing, for the best and most accurate results. Don't mix large amounts of indigo carmine solution, because it's not stabile and will break down within two months. None of the chlorate reagents mentioned here seem to be stabile.

 

WSM

Edited January 24, 2015 by WSM

[WSM]

I am ignorant, and therefor afraid, of chlorate.

Chlorates aren't something to fear, but we should understand and respect them. The safest method to teach yourself about chlorates is to work with them, providing you're wise and work in very small quantities (small accidents are easy to walk away from; larger ones, not so much).

 

As with so many things which are dangerous, proceed with caution till you understand their character and nature. When in doubt, ask.

 

WSM

Edited January 23, 2015 by WSM

[Ubehage]

Thank you

[WSM]

Thank you

 

You're welcome.

 

If you're not sure about how to do something you're curious about, feel free to ask. Someone (or several) here will offer helpful suggestions.

 

WSM

Edited January 24, 2015 by WSM

[pyrojig]

Thanks for the clarification on the spot test formulation ;. All good points made.

 

As for what WSM said, you WILL find many knowledgeable folks that would be more than happy to help you along the way.

[50AE]

Hi guys, I'm glad you did achieve so much experience and knowledge through these years.

 

You've inspired me to (maybe) try something new - automated pH control. Part of something I would call the ultimate DIY chlorate cell.

 

To build an automated pH control, the hardest part would be trying to find chemical resistant mechanical parts. Also, to find a reliable and not very expensive pH meter for constant immersion duty.

Although I think if someone tweaks the constant of HCl flow by trial and error, there is no need of auto pH regulation. I did it in previous times.

 

In my vision, the ultimate cell would be

 

1. Yield more than enough to satisfy one's needs

2. Efficient

3. Stirred electrolyte mechanism. This would ensure better electrolyte uniformity and lesser trapped base/acid in the crystals. Are some of you familiar with the horrible smell when you crush KClO3 crystals?

4. Autonomous. This means also a safety mechanism when faulty mains happens. A UPS for example.