making potassium (per) chlorate

[TomasBrod]

Hello!
Cathodes: I settled on two cathodes surrounding the anode. Cathodes are 3/4 of anode width each. + MMO anode.
Temperature: The cell is running hot (not confortable to hold with hand). As far as I understand, high temperature does not counteract the desired reaction.
Container: 2 liter glass container. Glass should handle high temperatures. 20L is too much for me to confortably handle, but smaller bucket is OK. In fact I have one ready.
Power: replaced the cables with thicker made of many copper strands, there is still some loss but no heating like before.
I understand the different solubilities so I have some solid NaCl on the bottom since start.

I fear I am doing something wrong. The anode is bubbling, not as much as cathodes but notably. Since the chlorine smell is very faint I suspect this is oxygen which should stick to chlorine. I am sure there is no fluorine in solution, maybe some iron from cathodes but that should precipitate.

I stopped measuring current and time (i shouldn't), but tried anyhow to freeze my electrolyte and got some crystals . Looks I am in right direction, but I expected more for that much current.

Thanks for the long replies!

[WSM]

Hello!

Cathodes: I settled on two cathodes surrounding the anode. Cathodes are 3/4 of anode width each. + MMO anode.

Temperature: The cell is running hot (not confortable to hold with hand). As far as I understand, high temperature does not counteract the desired reaction.

Container: 2 liter glass container. Glass should handle high temperatures. 20L is too much for me to confortably handle, but smaller bucket is OK. In fact I have one ready.

Power: replaced the cables with thicker made of many copper strands, there is still some loss but no heating like before.

I understand the different solubilities so I have some solid NaCl on the bottom since start.

I fear I am doing something wrong. The anode is bubbling, not as much as cathodes but notably. Since the chlorine smell is very faint I suspect this is oxygen which should stick to chlorine. I am sure there is no fluorine in solution, maybe some iron from cathodes but that should precipitate.

I stopped measuring current and time (i shouldn't), but tried anyhow to freeze my electrolyte and got some crystals . Looks I am in right direction, but I expected more for that much current.

Thanks for the long replies!

 

Hi TomasBrod,

 

The high temperatures are okay, in fact some folks actually wrap insulation around their cell to keep the temperatures higher.

 

Two liters sounds small for the size of electrodes seen in your photo (I'm guessing). If the smaller bucket you're talking about is similar to what we have here in the US, it might be a 2 gallon size or similar. That's about 7.5 liters and a good size.

 

Using many smaller wires instead of single larger ones is a good idea if your access to a variety of wires is limited. The total overall diameter of the copper wires is what's important for meeting the current demand of your electrodes. Whether one or many wires are used doesn't matter, so excellent choice on your part.

 

I think you have nothing to fear. It sounds like your system is working right. If the cell isn't pumping out chlorine, I wouldn't worry (oxygen and hydrogen are normal, chlorine is not).

 

Measuring current and time are important, but for NaClO₃ crystal recovery, measuring the temperature is vital. Be sure not to go below -20^oC, where NaCl will start dropping out also. Keeping the electrolyte at -15^oC or above will help assure that only chlorate drops out. Don't worry about low yields; most of the chlorate is still in solution and will come out in later runs (after recharging the spent electrolyte with chloride and running again). I think subsequent runs will produce chlorate in shorter amounts of time, OR more in the same amount of time (it works out to be more, in any case, because the electric energy is going into chlorate manufacture and not the precursors as much).

 

Keep up the good work, and thanks for sharing your experiences.

 

WSM

[TomasBrod]

The high temperatures are okay, in fact some folks actually wrap insulation around their cell to keep the temperatures higher.

 

Two liters sounds small for the size of electrodes seen in your photo (I'm guessing). If the smaller bucket you're talking about is similar to what we have here in the US, it might be a 2 gallon size or similar. That's about 7.5 liters and a good size.

 

Using many smaller wires instead of single larger ones is a good idea if your access to a variety of wires is limited. The total overall diameter of the copper wires is what's important for meeting the current demand of your electrodes. Whether one or many wires are used doesn't matter, so excellent choice on your part.

 

I think you have nothing to fear. It sounds like your system is working right. If the cell isn't pumping out chlorine, I wouldn't worry (oxygen and hydrogen are normal, chlorine is not).

 

Measuring current and time are important, but for NaClO₃ crystal recovery, measuring the temperature is vital. Be sure not to go below -20^oC, where NaCl will start dropping out also. Keeping the electrolyte at -15^oC or above will help assure that only chlorate drops out. Don't worry about low yields; most of the chlorate is still in solution and will come out in later runs (after recharging the spent electrolyte with chloride and running again). I think subsequent runs will produce chlorate in shorter amounts of time, OR more in the same amount of time (it works out to be more, in any case, because the electric energy is going into chlorate manufacture and not the precursors as much).

Thanks, I don't worry about catabolic reactions now. The bucket is Polypropylene 6.4L (1.7gal) of usable volume and large enough for my electrode.

The anode electrode is that big, because I cut one fourth of the original mesh. Why you advise me larger container? For heat? Electrolyte buffer? I can manage heat by turning the current (and voltage, Ohm's law) down.

The oxygen evolution is notable and if i remember, higher than with graphite electrodes.

Yeah, it was definitely not saturated. Like I forgot the high solubility of nachlorate or something. I am sure there is warmer than -20°C in my freezer, but to be sure I put a digital thermometer in there now.

 

A few leaves from red pelargonia fell in the cell (oh, autumn is here) and I fished it completely white after some time.

 

[WSM]

Thanks, I don't worry about catabolic reactions now. The bucket is Polypropylene 6.4L (1.7gal) of usable volume and large enough for my electrode.

The anode electrode is that big, because I cut one fourth of the original mesh. Why you advise me larger container? For heat? Electrolyte buffer? I can manage heat by turning the current (and voltage, Ohm's law) down.

The oxygen evolution is notable and if i remember, higher than with graphite electrodes.

Yeah, it was definitely not saturated. Like I forgot the high solubility of nachlorate or something. I am sure there is warmer than -20°C in my freezer, but to be sure I put a digital thermometer in there now.

A few leaves from red pelargonia fell in the cell (oh, autumn is here) and I fished it completely white after some time.

 

The bucket sounds like a good size for the electrodes you're using.

 

Yes, controlling the temperature by managing the power can work but be sure the voltage doesn't drop much below 2.0 Vdc. If I remember correctly, somewhere between 1.5 V and 2.0 V is a lower limit where the electrodes can operate without damage. For system component safety, if I'm correct, don't let the cell try to operate below about 2.5 Vdc.

 

I suggested the larger container for the reasons you mention, plus if it's larger (more volume of solution and mass of salt available) the system will run slower and be easier to control (plus, you'll realize greater yields). If things run in a much shorter time (like in a small cell), they happen faster and if something goes wrong, it can get out of control very quickly.

 

The digital thermometer is a good idea. I bought an inexpensive IR scanner on eBay, which gives a fast read of the temperature in the freezer (and if the freezer is dedicated to the job of salt recovery, mounting the sensor inside and the digital display outside is a good idea). If using a scanning IR thermometer, point it at opaque items, as transparent containers tend to give false readings.

 

I believe the best situation is to keep the NaCl levels high enough for the NaClO₃ levels to rise to where recovery of the crystals can be optimized. The trick is keeping the chlorides in solution and solid chlorides out of the chlorate crystals harvested. This is facilitated by decanting the electrolyte solution away from the solid NaCl crystals and chilling just the liquid electrolyte. I find that when I do so, I get (I believe) pure NaClO₃ crystals to form as the liquid is chilled (I haven't analyzed the crystals for purity yet).

 

Enjoy the cool Autumn weather. I live in the Western US and typically, our hottest weather locally is September-October . I look forward to cooler weather after that.

 

WSM

Edited September 5, 2016 by WSM

[taiwanluthiers]

I think before anyone talks about making perchlorate, there should be some leads as to where anyone can get LD anodes. Not "plate it yourself" because it's very involved (requires a full lab, lots of chemicals, etc.).

 

Otherwise it's going to just become like "sure it's easy to make perchlorate, if you can get some anode made out of unobtainium or some other such material"

[WSM]

I think before anyone talks about making perchlorate, there should be some leads as to where anyone can get LD anodes. Not "plate it yourself" because it's very involved (requires a full lab, lots of chemicals, etc.).

Otherwise it's going to just become like "sure it's easy to make perchlorate, if you can get some anode made out of unobtainium or some other such material"

 

That's true; LD anodes are hard to come by. If there's no way or means to buy it, then making them might be the only option.

 

Of the two types of LD anodes I've managed to buy in past years, both were manufactured in China. If we're lucky, we can find an importer who buys LD anodes from China and resells them to the public for a reasonable price (and then there are those who mark them up to an unreasonable price). Another option is a co-op purchase from China and assuming whatever risks are involved with that sort of venture.

 

If we can find a way to get lead dioxide (beta form) on either a CP titanium or graphite base for anodes, then yes; making perchlorates is much easier.

 

WSM

Edited September 5, 2016 by WSM

[taiwanluthiers]

Thing is, if you can make LD anodes, then you can easily buy perchlorate. It doesn't help those in countries where perchlorate is either banned or expensive since if perchlorate is banned it is likely the stuff needed to make anode is hard to come by too.

[WSM]

Thing is, if you can make LD anodes, then you can easily buy perchlorate. It doesn't help those in countries where perchlorate is either banned or expensive since if perchlorate is banned it is likely the stuff needed to make anode is hard to come by too.

 

It is possible to make your own precursors for LD plating (according to the published literature). Since I was able to buy a few LD (on CP titanium) anodes, I haven't done more than acquire a few required precursors for the LD plating process. One day, I may just give it a go...

 

I'm still being encouraged to pursue the bismuth-ruthenium pyrochlore route to perchlorate production (and I still have a small collection of materials required to make them, on hand).

 

We'll see...

 

WSM

Edited September 5, 2016 by WSM

[TomasBrod]

I am sad to tell you, that the anode failed for me.

I came to the cell that was clear (no clouds of hydrogen tinybubbles) and very small current was flowing, anode was bubbling a bit with strong chlorine odor. I done a quick test of reversing polarity on bottom 2 cm of anode. It acts like a diode. By reading other threads (SM) I came to conclusion that layer of titanium dioxide formed. On the bright side I have 3/4 of good mmo mesh left and can reuse this failed one as cathode.

Possible causes: dissolved Lacquer, E535 anti-caking agent, Iron ions, Calcium from water, dissolved Glass, KI despite the salt was marked not iodted.

I will discard the electrolyte.

Edit: at 10V (for a few seconds, of course) bubbles appear.

Edited September 6, 2016 by TomasBrod

[WSM]

I am sad to tell you, that the anode failed for me.

I came to the cell that was clear (no clouds of hydrogen tinybubbles) and very small current was flowing, anode was bubbling a bit with strong chlorine odor. I done a quick test of reversing polarity on bottom 2 cm of anode. It acts like a diode. By reading other threads (SM) I came to conclusion that layer of titanium dioxide formed. On the bright side I have 3/4 of good mmo mesh left and can reuse this failed one as cathode.

Possible causes: dissolved Lacquer, E535 anti-caking agent, Iron ions, Calcium from water, dissolved Glass, KI despite the salt was marked not iodted.

I will discard the electrolyte.

Edit: at 10V (for a few seconds, of course) bubbles appear.

That's unfortunate. At least you have more MMO to work with. I hope things go better from here on.

 

WSM

[WSM]

This morning, I submitted part fifteen of the series on Homegrown Oxidizers. I think it'll be published in the PGI bulletin by early next year.

 

This part details the first run of the sodium chlorate experiment through to harvesting the product. The project has been on hold since then for maintenance and reworking the setup.

 

Also, we're focusing on purifying the salt used for recharging the depleted liquor and additions while the second and later runs are operating; in an effort to keep the final products as pure as possible. Why go to all this effort to end up with an inferior product?

 

As always, there's more to come...

 

WSM

[WSM]

I had a problem. I had a piece of 0.050" thick CP titanium sheet metal and wanted to cut it in half to make some large cathodes. This sheet metal plate was 8" x 10" and I wanted two 4" by 10" plates. Smaller cathode plates were easy enough to cut with a hacksaw, but this piece was too big for that.

 

I tried to cut it at work, but kept running into roadblocks (timing issues, unavailable equipment or the machinist was out of the office). I gave up on getting it done away from home.

 

The solution? I bought some metal cutting blades for my jigsaw and carefully cut the piece in half, following a straight line drawn with a permanent marker pen. This was so straight forward and simple, I wish I had thought of it sooner. All that was required to finish the cut edges was to file off the burrs and that was it.

 

Now if I need to make custom sized cathode plates from large sheets of CP titanium, I'm going to do it myself at home rather than bother trying to get it done by professionals. They don't have to look perfect, just perform properly; and these do!

 

WSM

[TomasBrod]

That's unfortunate. At least you have more MMO to work with. I hope things go better from here on.

 

Yes. But if I retry this electrolysis with same materials I can expect same outcome. What do you think killed the anode?

Oh, and it looks brighter (whiter) than the unused piece.By using this failed piece as a cathode I can at least rule the corroded iron out.

 

• use pure water for your electrolyte (distilled, deionized, RO water or even filtered rainwater)
• Use pure or purified salts, or salts of known quality

[WSM]

Yes. But if I retry this electrolysis with same materials I can expect same outcome. What do you think killed the anode?

Oh, and it looks brighter (whiter) than the unused piece.By using this failed piece as a cathode I can at least rule the corroded iron out.

Help me remember as many parameters of your setup as you can:

• what type/source of water?
• what type/source of salt?
• what sort of power supply and the output voltage and current?
• was there any damage to the glass container at all?

Any other detail, no matter how small, that could give us a clue as to what might have caused the failure?

 

Thanks. We'll see if we can unravel this mystery.

 

WSM

Edited September 11, 2016 by WSM

[TomasBrod]

• what type/source of water?
• what type/source of salt?
• what sort of power supply and the output voltage and current?
• was there any damage to the glass container at all?

Any other detail, no matter how small, that could give us a clue as to what might have caused the failure?

 

Thanks. We'll see if we can unravel this mystery.

No damage to glass. Power supply was modified pc-at psu set at about 4V.

Water was from tap, but here the water is very good quality and good for drinking.

I now discovered the salt was iodated iodized so that was probably the cause.

Next run is put off until December as I have to travel to school. Will definitely use pure salt and maybe distilled water.

[WSM]

No damage to glass. Power supply was modified pc-at psu set at about 4V.

Water was from tap, but here the water is very good quality and good for drinking.

I now discovered the salt was iodated iodized so that was probably the cause.

Next run is put off until December as I have to travel to school. Will definitely use pure salt and maybe distilled water.

Distilled water (or deionized water) is a good way to start, by eliminating interfering ions. As for the salt, I've discovered that even those which are labeled "Pure" (such as the "pure" water softener salt I bought), usually aren't pure NaCl but full of the chlorides of calcium, magnesium and other things (and dirt, silt and chunks of rust and small stones). I even bought expensive salt water pool salt, which is purer, but it also tested positive for calcium and magnesium (but much less than the water softener salt).

 

If you have a clear sodium chloride brine, you can test it with a solution of sodium carbonate (Na₂CO₃, I use a 1M solution; 105.9888 grams per liter of distilled water). If it turns milky or white, there are calcium and/or magnesium ions present.

 

To purify the brine, I've removed the finely powdered calcium and magnesium precipitates by vacuum filtration using slow grades of laboratory filter paper (and patience) and then treated the filtered, pure brine (now alkaline because of the treatment used to remove the contaminants) with HCl to reduce the alkalinity to a pH of 7 or slightly lower.

 

When I started on this adventure, I never realized how much "real chemistry" (rather than "cookbook chemistry") I'd be using.

 

WSM

Edited September 15, 2016 by WSM

[WSM]

Happy Autumnal Equinox to those of us in the Northern hemisphere. Happy Vernal Equinox to the rest of us.

 

WSM

 

Edit: Okay, it appears that I'm about nineteen hours early for my location.

Edited September 21, 2016 by WSM

[WSM]

Thing is, if you can make LD anodes, then you can easily buy perchlorate. It doesn't help those in countries where perchlorate is either banned or expensive since if perchlorate is banned it is likely the stuff needed to make anode is hard to come by too.

 

As I've said before; I don't make chlorates or perchlorates because I need to, I do it because I want to. My location and circumstances won't allow me to manufacture pyrotechnics and display them at will, so I've turned my energies toward learning how to produce my own raw materials.

 

It's a challenging and satisfying endeavor, learning to be more self-sufficient.

 

WSM

[WSM]

If you make an other gallon of saline then you can always have a cell full electrolysing and a gallon in the fridge, Then after a day or so pour the harvested liquor back with added salt and cause the next gallon to overflow to a cooling jar.

For the mass of crystals harvested add about half that mass of salt into solution to replenish the ingredients. So if you harvest 1kilo add about 500g of dry salt.

 

This sounds like a good "rule of thumb" to follow. When I get a good stock of purified and dried salt for the system, I'll try it and see.

 

I suspect the extra effort applied in the making of pure starting materials will assist in acquiring the highest grade of finished products in the end. We'll see...

 

WSM

[greenlight]

Hi, I have been making chlorate in a small 1l cell with a 5v 20 amp power supply from KCl. It takes me 95 -100 hrs to get 365g but I think it is because of the connections and I have since replaced them with bigger cables and larger alligator clips. It still heated up considerably when running before I changed the connections and cabling and required a water bath.

 

I want to try a perc cell and also have a 5v 40 amp power supply but I think it will overheat with that amperage in a small 1 litre vessel so I will stick to the same 5v 20 amp.

Can I charge the new cell with sat. NaCl solution and run it for the required time to convert most of the chloride to chlorate with an MMO anode?

Then can I switch to the platinized anode and continue from there checking for signs of perchlorate formation with methylene blue solution?

Finally, double decomp with KCl and recrystallise to get rid of as much chlorate as possible?

 

Any help is greatly appreciated

Edited September 28, 2016 by greenlight

[pyrojig]

Green light you might consider a larger container (to dissipate the heat ) to rest the cell in. It would have to be changed every so often , but may help as a heat sink.

 

Wsm: please do persue the research on the pyrochlore. A ground breaking finding may be I store . Of which I believe you should have credit for . At least proving its merit . I eagerly await new findings .

Edited September 29, 2016 by pyrojig

[greenlight]

Yes, I used one for the chlorate cell because the temperature was getting quite high without it.

 

So what the steps I wrote are correct and I can begin?

[WSM]

Hi, I have been making chlorate in a small 1l cell with a 5v 20 amp power supply from KCl. It takes me 95 -100 hrs to get 365g but I think it is because of the connections and I have since replaced them with bigger cables and larger alligator clips. It still heated up considerably when running before I changed the connections and cabling and required a water bath.

I want to try a perc cell and also have a 5v 40 amp power supply but I think it will overheat with that amperage in a small 1 litre vessel so I will stick to the same 5v 20 amp.

Can I charge the new cell with sat. NaCl solution and run it for the required time to convert most of the chloride to chlorate with an MMO anode?

Then can I switch to the platinized anode and continue from there checking for signs of perchlorate formation with methylene blue solution?

Finally, double decomp with KCl and recrystallise to get rid of as much chlorate as possible?

Any help is greatly appreciated

 

From my experience, I'd say it's better to separate the steps and purify the products as you go. It's very difficult to separate the contaminants at the end when they're intimately mingled with the end product.

 

To make sodium chlorate from chloride takes two steps. First run the chlorate cell till the chloride is nearly gone, then recharge with chloride and run it again. This is because the chlorate from the first run is about half the concentration desired for a perchlorate run. The platinum anode is attacked in the cell if the chlorides are too high; so aim for a high chlorates, low chlorides electrolyte in your (platinized titanium anode) perchlorate cell.

 

After you run the perchlorate cell, destroy the residual chlorate before adding potassium chloride solution, or your product will be mixed KClO₃ and KClO₄, and it may as well be all chlorate. A most cost effective way to destroy residual chlorate is with SO₂ gas. I used sodium metabisulfite solution, added slowly, deep in the NaClO₄ solution, which kept the SO₂ gas in the oxidizer solution where it could do it's job and not flash off and be wasted.

 

It's important to test for chlorate between doses so you know when the chlorates are absent. At that point stop the dosing and convert to potassium salts with KCl solution. Vacuum filtering quickly separates the KClO₄ powder from the dissolved sodium salts. Next soak the perchlorate powder in cold distilled water and vacuum filter again with distilled water rinsing. At this point your potassium perchlorate should be quite pure.

 

Read my blogs for more details of how I did it last year.

 

WSM

[WSM]

Wsm: please do persue the research on the pyrochlore. A ground breaking finding may be I store . Of which I believe you should have credit for . At least proving its merit . I eagerly await new findings .

 

I haven't given up on the pyrochlore, but it's on the back burner. I have a little of the materials for the attempt, but more important than that is the procedure. I need to have a solid grasp on the proper parameters to establish for success or I'm likely to waste a lot of time, material and money fooling around without a clear understanding of how to go about it.

 

I plan to get to it later on.

 

WSM

[WSM]

Yes, I used one for the chlorate cell because the temperature was getting quite high without it.

So what the steps I wrote are correct and I can begin?

 

Is it possible for you to use a larger container for your cell? One liter is very small. I've used a one gallon jar for a cell (3.785 liters) and it does heat up (about 55^oC), but it worked.

 

Can you post a photograph of your setup? It doesn't have to be beautiful, just clear enough for us to visualize what you're describing. Thanks.

 

WSM