making potassium (per) chlorate

[sefrez]

I see. I used that same procedure when I started out using crap expensive food grade salt. It had calcium silicate in it as anti-cake which was a pain to filter off. I noticed treating it with NaOH caused additional calcium silicate to come out of solution (along with anything else) and it made the calcium silicate easier to filter because it consolidated into fluffy web like structures. I used HCl to neutralize after.

 

Now, like you, I use water softener. Since using this source for Na/KCl, I have stopped that purification step and now just dissolve the large crystals/pellets in the cell solution directly and filter off the obvious impurities - which isn't that much. I can't remember for sure, but I think I did both acidification and basification to a solution of the KCl salt and no precipitates were found. I know I didn't do it with the NaCl. Though, instead of pellets, they are large crystals which appear quite pure. It is nice to have brine solutions ready to go as opposed to needing to dissolve the salt in the cell each time it needs to be replenished, but I was having to boil down the solution a lot with adding brine which was really annoying. I guess if you have a high temperature cell, that isn't as much of a problem because of higher water vapor leaving in the process.

 

What brand of softener do you use? I am using Diamond Crystal.

 

I do still get white precipitate on the cathodes that needs to be brushed off after a while, but I got that even with the purification step when using the food grade salt.

Edited September 20, 2021 by sefrez

[WSM]

"What brand of softener do you use? I am using Diamond Crystal."

 

 

I use the cheapest grade I can find, usually sundried sea water. It has a considerable amount of dissolved calcium and magnesium contamination, besides the visible sand, gravel and rust scale that somehow got into the mix of salt crystals. Then again, even high priced, "purified" salt water pool salt showed signs of calcium and magnesium, so I figured why waste the money?

 

WSM

Edited September 23, 2021 by WSM

[WSM]

I see. I used that same procedure when I started out using crap expensive food grade salt. It had calcium silicate in it as anti-cake which was a pain to filter off. I noticed treating it with NaOH caused additional calcium silicate to come out of solution (along with anything else) and it made the calcium silicate easier to filter because it consolidated into fluffy web like structures. I used HCl to neutralize after.

What brand of softener do you use? I am using Diamond Crystal.

I do still get white precipitate on the cathodes that needs to be brushed off after a while, but I got that even with the purification step when using the food grade salt.

 

 

In my research, I discovered that sodium carbonate solution, when made from dry sodium carbonate , is highly alkaline due to part of it also forming some hydroxide. The carbonate is used to "soften" hard water, i.e., drop out the minerals as precipitates, which is what we want. After filtering the fine, white precipitates of magnesium and calcium (plus whatever else drops out), the (alkaline) purified brine can then be neutralized with dilute hydrochloric acid and be ready for use as an electrolyte or reacting with other salts, as in the case of potassium chloride solution in sodium perchlorate solution, to drop out potassium perchlorate!

 

The latest episode of Homegrown Oxidizers (Part 18) has been languishing on my computer desktop for years, waiting for me to get back to purifying my KCl solution (and getting photos to add and document the efforts) in the process of making KClO₄ equal to or better than that made by industrial suppliers.

 

I plan to submit the finished articles to the PGI Bulletin for publication, but my continuing research is usually posted in this blog piecemeal as I collect my thoughts for the articles.

 

WSM

 

Edit: The white ppt on the titanium cathode plates or mesh can be anything contaminating the electrolyte, but I suspect it may just be titanium salts (oxides, etc.), though cathodic protection is meant to prevent that.

 

If it doesn't interfere with the chlor-alkali process, don't worry about it. But, if it does interfere, scrubbing it off the cathodes with abrasives between runs may be called for.

Edited October 3, 2021 by WSM

[WSM]

Happy Guy Fawkes night to our friends in the UK.

 

WSM

[Arthur]

The sky has been rent asunder on Friday night, Parties may also be held in the Saturday after (6th this year) let's see what tonight brings.

[WSM]

FYI: This morning I recalled an interesting note from my studies of home oxidizer production years ago, that I'm passing along.

 

I remember measuring the Voltage, Current and Temperature of my cell runs using digital meters connected to sensors (compatible with the horrible environment of the cell electrolyte).

 

The current level was common throughout the cell but the voltage varied depending on where it was measured from in the circuit. A friend and fellow amateur electrochemist suggested I move the voltage measurement point from the power supply to the connection point at the cell.

 

When I had done so I saw a distinct difference in the voltage reads, which helped me to more accurately determine the actual cell voltage (and more accurately determine the cell end-of-run time)!!!

 

Besides this benefit, I also learned not to exclusively trust the meters on certain power supplies, but having separate digital meters external to the PSU helps to confirm reads and may also show interesting discrepancies in reads between the two.

 

I found it useful to use Teflon coated thermal sensors in the harsh cell electrolyte during the run, for consistent accuracy.

 

WSM

[Andead]

Hi, Ive managed to obtain a pool chlorinator Cell that has a LOT of plates. Its been previously used so Im unable to tell which is Titanium and which is MMO. Should i presume that the outer plates are the Ti ones or I will need to somehow test. Also , Ive tried using it at 5V and outputting circa 5amps however the anode is flaking alot, are these cells designed for extremely low current or I should proceed as I am going?

[WSM]

Hi, Ive managed to obtain a pool chlorinator Cell that has a LOT of plates. Its been previously used so Im unable to tell which is Titanium and which is MMO. Should i presume that the outer plates are the Ti ones or I will need to somehow test. Also , Ive tried using it at 5V and outputting circa 5amps however the anode is flaking alot, are these cells designed for extremely low current or I should proceed as I am going?

 

 

I've never worked with a pool chlorinator, but I've had considerable experience (as an amateur) making and using MMO and titanium electrodes.

 

I've heard that some pool chlorinators use MMO on titanium exclusively, which seems odd to me. The only justifications I can see for that is either running the system on alternating current, or the ability to reverse the polarity of the cell intermittently (for some perceived benefit I'm unaware of).

 

If the pool electrodes were removed due to failure, they may be seriously compromised/damaged. MMO is chemically very tough and can withstand a lot of abuse if the conditions are right. Try soaking the plates in pool acid (hydrochloric acid) for 2-12 hours and see if they "clean up" and look or work better. I've used that method to clean brown smut off of used MMO electrodes in the past.

 

Be aware that reverse polarity on an MMO/titanium electrode set can be damaging to the integrity of the MMO, according to some reports (I haven't tried it myself but it may be true).

 

Can take a photo of the unit and post it for us to see? Perhaps there is something in the appearance of it which would help better diagnose the issues you are observing.

 

WSM

 

Edit: If you have a good microscope, the condition of clean MMO can be investigated more easily. New MMO has a "cracked mud" appearance and used MMO has a similar but damaged look on a microscopic level.

Edited November 21, 2021 by WSM

[Andead]

 

 

I've never worked with a pool chlorinator, but I've had considerable experience (as an amateur) making and using MMO and titanium electrodes.

 

I've heard that some pool chlorinators use MMO on titanium exclusively, which seems odd to me. The only justifications I can see for that is either running the system on alternating current, or the ability to reverse the polarity of the cell intermittently (for some perceived benefit I'm unaware of).

 

If the pool electrodes were removed due to failure, they may be seriously compromised/damaged. MMO is chemically very tough and can withstand a lot of abuse if the conditions are right. Try soaking the plates in pool acid (hydrochloric acid) for 2-12 hours and see if they "clean up" and look or work better. I've used that method to clean brown smut off of used MMO electrodes in the past.

 

Be aware that reverse polarity on an MMO/titanium electrode set can be damaging to the integrity of the MMO, according to some reports (I haven't tried it myself but it may be true).

 

Can take a photo of the unit and post it for us to see? Perhaps there is something in the appearance of it which would help better diagnose the issues you are observing.

 

WSM

 

Edit: If you have a good microscope, the condition of clean MMO can be investigated more easily. New MMO has a "cracked mud" appearance and used MMO has a similar but damaged look on a microscopic level.

 

 

Sorry it has taken me so long to answer but my studies have had the best of me for the last month. I cant attach any photos of the chlorinator since Im not using my phone to post here. I broke down some of the plastic covering and have found out there are probably around 5 anodes which are MMO i presume due to some black-brown flakes coming off when I first started electrolysis. I am giving it at 4V around 5Amps and it has held up fine for the last couple of days. Interestingly the system they use is not typical in my eyes. The central anode has 2 cathodes and these 2 cathodes have another 2 anodes to their sides and then a final cathode is on the external side of each "set" of 2 anodes.

 

It looks something like this :

 

[Cathode} {anode}{Anode} [Cathode} {anode} [Cathode} {Anode} {Anode} [Cathode}

 

 

Thanks for the reply WSM

[Arthur]

Interleaved electrodes are common where it is required to gt lots of electrode surface area in a small space. For any process using platinum it is very important to use both sides of a thin sheet

 

For a commercial process cell it's not unusual to use between 1000a and 10,000a so a lot of surface area is essential

[Andead]

Interleaved electrodes are common where it is required to gt lots of electrode surface area in a small space. For any process using platinum it is very important to use both sides of a thin sheet

 

For a commercial process cell it's not unusual to use between 1000a and 10,000a so a lot of surface area is essential

 

 

Did not know about that they use such high currents. However in this case I doubt that a pool chlorinator requires that high of a current as its cell life is around 10 years and I doubt at 1000amps anything would last for a year at best let alone 10.

[WSM]

Did not know about that they use such high currents. However in this case I doubt that a pool chlorinator requires that high of a current as its cell life is around 10 years and I doubt at 1000amps anything would last for a year at best let alone 10.

 

 

Platinum is usually used for perchlorate cells, as a high chloride level would be detrimental to the anode.

 

In a chlorate cell using MMO and titanium, high chlorides are fine.

 

Interleaving the electrodes DOES save space in the cell. The required or planned current of the cell is dependent on the total surface area of the anodes, combined with the matching cathodes. The area of the anode used is based on the anode area matched to the cathode area (a single cathode matched to the anode demands about half the current of that same single anode surrounded by two matching cathodes).

 

Question: what are the dimensions of the anode and cathode plates?

 

I suspect soaking the saltwater pool chlorinator in full strength hydrochloric acid for a while would help remove any soluble contaminants from the electrodes. Let me know if you try it and how it works. Thanks.

 

WSM

Edited December 22, 2021 by WSM

[Arthur]

The factory making perchlorate for the NASA Solid Rocket Boosters may have more cells at more current to make more perc than all the world's amateurs could use. When there is a large demand for product nothing beats passing enough current to make the product in time.

[WSM]

The factory making perchlorate for the NASA Solid Rocket Boosters may have more cells at more current to make more perc than all the world's amateurs could use. When there is a large demand for product nothing beats passing enough current to make the product in time.

 

 

At full production there were two factories making ammonium perchlorate for government and private solid rocket engines. The demand was high and the production higher. As you may imagine, the electric energy consumption was massive.

 

Merry Christmas to All !

 

WSM

[Fried Chicken]

Is it still difficult to buy perchlorate?

[WSM]

Is it still difficult to buy perchlorate?

 

 

That depends.

 

Here in the USA, it's not difficult if you know where to look. Other places in the world vary considerably depending on where you are and the powers that be.

 

For some, making it is the only option, if you have the ability and means to do so.

 

Long story short, without knowing your particular situation it's difficult to give a more detailed answer.

 

WSM

[Fried Chicken]

 

 

That depends.

 

Here in the USA, it's not difficult if you know where to look. Other places in the world vary considerably depending on where you are and the powers that be.

 

For some, making it is the only option, if you have the ability and means to do so.

 

Long story short, without knowing your particular situation it's difficult to give a more detailed answer.

 

WSM

 

 

U.S.

 

Yeah I know where to look, but it’s someone i’ve bought aluminum from in the past. Possibility of getting flagged?

[WSM]

U.S.

Yeah I know where to look, but it’s someone i’ve bought aluminum from in the past. Possibility of getting flagged?

 

Maybe. The powers that be are trying to prevent illegal activity, and using a heavy hand in doing so.

 

If you're quietly pursuing pyrotechnic research and development and not being a nuisance, try getting different types of materials from other suppliers, to avoid being "flagged" as something/someone you're not.

 

WSM

Edited January 3, 2022 by WSM

[WSM]

It's been a few years since I've actually run a chlorate cell. Something I observed in laundry bleach has me concerned about the viability of old, stored electrolyte I've kept sealed in buckets all this time.

 

It seems that bleach doesn't really store all that well and will break down over time, releasing chlorine. It is rather unstable, which is why it works so well in the wet clothes washing process we're familiar with.

 

I suppose my old electrolyte is getting weaker, the longer it sits in storage.

 

With this in mind, I don't plan to toss out the old electrolyte, but re-charging it with chloride and running it for a while before going full bore on the next run will probably get it back to a properly functioning electrolyte for my sodium chlorate production goals.

 

We'll see...

 

WSM

[sefrez]

I definitely wouldn't toss it if it is loaded with valuable sodium chlorate. It would be good to know how the hypochlorite decomposes under these conditions. At boiling temperatures it is of course fast and some chlorate / chloride is produced. As far as the electrolysis process goes, this doesn't set you back really because its a disproportionation reaction in chlorine and the overall oxidation (oxidation sum) in solution remains the same. I'm sure some is lost through other reactions taking place, but the chlorate should be stable. Not that it matters as much for a potassium cell due to the low solubility of potassium chlorate, but it has been a few months since I have used the electrolyte (stored in a HDPE bottle) and it went completely clear as per my eyes and chlorine scent was hardly present. I re-loaded it with KCl a few days ago and started the cell about 13 hours ago. The solution is dark yellow / green again, as I expected. Some KClO3 has already precipitated.

[WSM]

I definitely wouldn't toss it if it is loaded with valuable sodium chlorate. It would be good to know how the hypochlorite decomposes under these conditions. At boiling temperatures it is of course fast and some chlorate / chloride is produced. As far as the electrolysis process goes, this doesn't set you back really because its a disproportionation reaction in chlorine and the overall oxidation (oxidation sum) in solution remains the same. I'm sure some is lost through other reactions taking place, but the chlorate should be stable. Not that it matters as much for a potassium cell due to the low solubility of potassium chlorate, but it has been a few months since I have used the electrolyte (stored in a HDPE bottle) and it went completely clear as per my eyes and chlorine scent was hardly present. I re-loaded it with KCl a few days ago and started the cell about 13 hours ago. The solution is dark yellow / green again, as I expected. Some KClO3 has already precipitated.

 

 

Yes, that makes sense. I expect your chlorate production to be faster since the recharged and used electrolyte has existing precursor chemicals in it. Your subsequent yields should be higher as well.

 

If your starting materials are refined and pure, your end product will be high quality, and contaminants won't accumulate as much with subsequent runs of the recharged cell liquor.

 

WSM

[sefrez]

Yeah, the KCl water softener seems to be reasonably pure. I recrystallize once with distilled water and the solution left over is saved and used for rinsing the harvested crystals of the next batch from the cell electrolyte. It seems to be a good start for cleaning the crystals of the next batch given it should be saturated in chlorate from the recrystallization of the previous batch (at ~ 0C) and therefore should not dissolve more chlorate. Overall, purification is a rinse with the said solution (chilled to almost 0C) and then the cleaned crystals recrystalized. I do heat them to about 120-150C after they have mostly dried to make sure no hypochlorite remains.

[WSM]

Yeah, the KCl water softener seems to be reasonably pure. I recrystallize once with distilled water and the solution left over is saved and used for rinsing the harvested crystals of the next batch from the cell electrolyte. It seems to be a good start for cleaning the crystals of the next batch given it should be saturated in chlorate from the recrystallization of the previous batch (at ~ 0C) and therefore should not dissolve more chlorate. Overall, purification is a rinse with the said solution (chilled to almost 0C) and then the cleaned crystals recrystalized. I do heat them to about 120-150C after they have mostly dried to make sure no hypochlorite remains.

 

 

You obviously have better quality KCl water softener salt than I do. My KCl water softener salt pellets seem to have chunks of iron rust and other debris in some of them.

 

When I make my brine, I first dissolve the KCl pellets in a poly tank with distilled water, using a pump to circulate the water through the pellets. When the pellets are fully dissolved, I filter any obvious contaminants out with a vacuum filtration setup.

 

That was before. My new process adds in chemical treatment of the clear brine to remove unseen contaminants, typically calcium, magnesium and some soluble iron. To the clear brine I add a 1M solution of potassium carbonate, which drops those contaminants out as flocculant precipitates. After the precipitates drop to the bottom of the reaction vessel (I use clean, new 5 gallon PE buckets), I carefully decant the clear liquid into another bucket and then vacuum filter the sludge, using SLOW grade lab filters to remove the very fine precipitates from the last bit of clear brine.

 

The final step is to test the pH of the purified brine, which is usually left alkaline after treatment with K₂CO₃ solution. I then neutralize the brine with dilute HCl solution and store my purified brine for later use in electro-chemical cells or for creation or potassium salts by metathesis.

 

If your KCl brine is clear (a good first step), you may want to test a sample of it with potassium carbonate solution and see if any cloudiness is observed. When I did this with my sodium chloride brine, using sodium carbonate solution, it looked like milk! I believe potassium chloride brine would react the same to potassium carbonate solution.

 

If you try this, let us know what happens. Thanks.

 

WSM

[TOMMOR2012]

My CHLORATE cell has gone green . What causes this ???

 

[WSM]

My CHLORATE cell has gone green . What causes this ???

 

 

Is there ANY exposure to copper or stainless steel? Nickel compounds can be green, too. If you run the cell too long and the chloride level gets too low, there could be degradation of the electrodes.

 

Other than that, we need more information about your setup to help figure out the problem.

 

WSM

 

Edit: Can you post photos?

Edited March 13, 2022 by WSM