making potassium (per) chlorate

[WSM]

The sodium chlorate cell has been running for 65 hours. As an experiment, I've recovered about 3.3 liters of the electrolyte, transferred it into a PETE jar and put it in a spare refrigerator we keep for overstock foodstuffs. The electrolyte in the jar measured about 54.2^oC and the fridge is about 2^oC where the jar is put.

IMGP7903.JPG

Draining the sample from the cell

IMGP7904.JPG

The sample transferred to a PETE jar and placed in the fridge

The electrolyte has a distinct yellow tint and looks similar to the potassium chlorate electrolyte I've worked with in the past. I'll wait till the electrolyte is down to 2^oC and see if any sodium chlorate drops out.

I plan to continue with the non-pH controlled experiment for a while, and then add in pH control (plus dial it in) and note the difference during later running of the cell.

More to come ...

WSM

 

No crystals dropped out; but by the conversation I had with a friend, and fellow electrochemist, after I posted the message above; I'm not surprised. Judging by the size of the operation and the amount of material involved; after some quick off-hand calculations, we realized it'll take weeks to get a high enough chlorate concentration to drop out chlorate crystals.

 

It's not a problem, it's just that patience is required here .

 

I poured the cool electrolyte back into the cell (which is running without interruption) and will continue running things till the chloride crystals I discovered on the bottom of the cell are absorbed into the electrolyte (probably from the failed screen in the salt reservoir which allowed salt slurry into the cell, early on) and more salt needs to be added.

 

I'll continue to monitor the progress so I can learn the idiosyncrasies of my setup and get familiar with the system and it's expected yield (probably several kilos of sodium chlorate crystals).

 

More later...

 

WSM

Edited May 31, 2016 by WSM

[taiwanluthiers]

Recrystallizing those agricultural grade potassium chloride is a pain though... It's an extra step that takes forever (because filter paper takes forever to admit the solution)

[memo]

does methylene blue react with sodium perchlorate or only potassium perclorate

[Mumbles]

Methylene blue reacts with any soluble perchlorate. Chemically, it's actually a chloride salt itself. When it encounters perchlorate, it forms methylthioninium perchlorate which is a very insoluble purple compound, and potassium or sodium chloride.

 

Along these same lines, has anyone tried using tetraphenylphosphonium chloride? I was browsing through a book called the "Handbook of Anion Determination" on google books and saw it mentioned. It works on the same principle as Methylene blue, but may be cheaper. It can easily be made at least. The one downside is that it's colorless. I have a feeling this would be better suited for a sodium cell however. It may lead to some ambiguity in distinguishing the precipitated perchlorate salt from the normally poorly soluble potassium salt.

[Arthur]

 

No crystals dropped out; but by the conversation I had with a friend, and fellow electrochemist, after I posted the message above; I'm not surprised. Judging by the size of the operation and the amount of material involved; after some quick off-hand calculations, we realized it'll take weeks to get a high enough chlorate concentration to drop out chlorate crystals.

...

 

WSM

IMO you will need to add twice the saturated amount of chloride to get enough chlorate to ppt out with a reasonable temperature fall, OK the chiller makes things easier. so if you weigh out twice the saturated solubility of chloride and fully electrolyse all of it then there should be lots of chlorate to ppt out when you drop the temperature 40 or 50 degrees C.

[WSM]

Recrystallizing those agricultural grade potassium chloride is a pain though... It's an extra step that takes forever (because filter paper takes forever to admit the solution)

 

That's true unless you apply vacuum filtration. If you do a Google search of Buchner funnel, you'll see several diagrams and photos of the vacuum filtration equipment I'm referring to.

 

For convenience in filtering large quantities of material, I've started using a Bench top or table top Buchner funnel. Having a quality vacuum pump helps also.

 

My first vacuum pump was a surplus freezer compressor I acquired from my parents when they decided to get rid of their old upright freezer (they asked me if I wanted anything from it). I connected a lab faucet to the intake tube of the freezer compressor, and with a tubing fitting was able to draw down to almost 29 inches of mercury! I used it for years before the motor seized and I had to dispose of it.

 

Now I use a small laboratory vacuum pump I bought on eBay. It was sold for "parts or repair"; and when I read the description it sounded like I could work with it. When it arrived, I disassembled it and found out it had a sheared roll pin, which I replaced for ten cents. After reassembly, I put in vacuum pump oil, drained it out and refilled the pump with clean, new vacuum oil. It's been working nicely ever since.

 

You could probably get away with using a water aspirator for a vacuum source, which run as low as $15 to $20 if you shop carefully.

 

Vacuum filtration is MUCH faster than depending on gravity alone, and I highly recommend it.

 

WSM

Edited May 31, 2016 by WSM

[WSM]

IMO you will need to add twice the saturated amount of chloride to get enough chlorate to ppt out with a reasonable temperature fall, OK the chiller makes things easier. so if you weigh out twice the saturated solubility of chloride and fully electrolyse all of it then there should be lots of chlorate to ppt out when you drop the temperature 40 or 50 degrees C.

 

I intend to continue running the cell and add in more chloride periodically as it's consumed in the process, Till the chlorate is saturated enough to drop out when the chloride is added in. I suppose then chilling the electrolyte will yield respectable amounts of sodium chlorate.

 

Afterward I'll recharge the electrolyte with more chloride and keep running the cell.

 

After two harvesting cycles, I hope to add in pH control to the cell and note the difference between running it with and without an ideal pH for efficiency.

 

WSM

Edited May 31, 2016 by WSM

[MrB]

 

You could probably get away with using a water aspirator for a vacuum source, which run as low as $15 to $20 if you shop carefully.

 

 

Is that a venturi? In that case, check waterbed supplies, those are made from plastic, and you might need to use some adapter to hook it to a rigid tube, but cost as little as 5 bucks here. eBay has some "irrigation supplies" styled ones, that cost as little as 2 bucks, but i have no idea on the flow you could expect from one of those.

A waterbed style one, pulls about a cubic meter of water every two hours, based on my system pressure from the tap. But that is with no resistance, i assume it will perform worse within a system like this. But it should still cut down the filtration time i suppose.

B!

[memo]

doing some reading and watching a few videos it seems i am running my volts to low. i am at 5.5 v and need 6,5 to 7 v and my amps are high at 46 i need 25 amps. i am using 2 600 watt computer power supplies in paralell. is there a way to be able to ajust your volts and amps with this power supply ? my temp is s little low also should be 80 to 90 c. that should be easy to fix with a little insulation. any ideas ?

 

memo

[WSM]

doing some reading and watching a few videos it seems i am running my volts to low. i am at 5.5 v and need 6,5 to 7 v and my amps are high at 46 i need 25 amps. i am using 2 600 watt computer power supplies in paralell. is there a way to be able to ajust your volts and amps with this power supply ? my temp is s little low also should be 80 to 90 c. that should be easy to fix with a little insulation. any ideas ?

memo

 

Hi memo,

 

Remind me what the dimensions of your anode are (centimeters are okay)? When we know the area of the anode and it's configuration (flat sheet, mesh or whatever), we can make intelligent suggestions.

 

Thanks.

 

WSM

[taiwanluthiers]

When I was making chlorate in Taiwan I got a buchner funnel cheap at a lab supply place. I used a shop vac to supply the vacuum (I just held the hose to the flask) which sped things up but it was clearly straining the shop vac, not to mention there's a serious mismatch between the fitting on the buchner funnel flask and the shop vac hose...

 

The only thing is, I read that lab glassware is illegal in Texas unless you have a permit... I don't want to get arrested for having lab glassware (or be mistaken for a meth lab).

 

I remember in high school when we used a buchner funnel we used the venturi on the water faucet.

Edited June 1, 2016 by taiwanluthiers

[memo]

 

Hi memo,

 

Remind me what the dimensions of your anode are (centimeters are okay)? When we know the area of the anode and it's configuration (flat sheet, mesh or whatever), we can make intelligent suggestions.

 

Thanks.

 

WSM

 

the anode is 2 inches by 3 inches and is platinum coated mesh the cathode is 1 1/2 x 6 inches stainless steel flat sheet .

Edited June 2, 2016 by memo

[WSM]

the anode is 2 inches by 3 inches and is platinum coated mesh the cathode is 1 1/2 x 6 inches stainless steel flat sheet .

Thanks, memo.

 

The method I use to calculate the current demand of the anode is this:

• determine the area by multiplying the length and width of the anode (2" x 3" = 6 in²)
• calculate the area in cm² (6.45 x 6 in² = 38.7 cm²)
• multiply by the typical current load (0.3 A x area in cm² for MMO, and try 0.2 A for Pt or 38.7 cm² x 0.2 A = 7.74 A demand)

So if you want to lightly load your platinum anode to make it last for perchlorate production, load it no more than about 8 amps. When I did that with a constant current (CC) power supply, the anode ran smoothly and showed no physical damage (and it did produce sodium perchlorate). I ran the perchlorate cell at 4.2 Vdc and about 15 amps, constant current (the Pt anode I used is a different size than yours). Everything ran smoothly.

 

MMO is very hardy in a chlorate cell and can take a lot of abuse without breaking down as easily as platinum. The same size anode in MMO, running at 0.3 A / cm² demands 11.61 amps (double that if you surround the anode with two cathodes, or 23.22 amps).

 

Many amateur electrochemists make the mistake of driving their platinum anodes too hard and causing them to fail (the platinum is dissolved and the anode becomes useless). I wanted to avoid that mistake in my perchlorate experiments, and so far I've succeeded.

 

I know a lot of the literature describes systems running with higher temperatures and currents, and I was surprised mine didn't need to do that and still performed well. I suppose the small scale I worked in allowed me to succeed without driving it too hard. I got an article about perchlorate systems that was an excellent guide for how I did it with the lead dioxide (LD) anode, and my numbers closely matched theirs, except for the size of my system being so much smaller.

 

WSM

Edited June 3, 2016 by WSM

[memo]

today I finished up the 3rd run, at room temp I had a bunch of very fine crystals. finer than any of the other runs. I had about 240 hours on this run. I was not able to get any methylene blue. there were 2 packages 1 with 1 with out, I didn't have my glasses and grabbed the wrong pack. this is not 100 % it has other things in it. the methylene blue was the 3rd thing on the list. is that going to work ?

 

the yield on this run is going to be way down from the last run. it is drying now..

 

 

memo

[Mike]

Yes that is no problem. I bought some as food colorant (nearly 100 % sugar), no problems.

[Arthur]

Pt electrodes don't like ripple on their electricity supply,

[memo]

went into town again today, took my glasses this time. i got the methylene blue and tested my perclorate that i just finished. the water is a very pretty color of blue but no violet or purple. now i have almost a kilo of non percloate crystals. what now ? I am kinda at a loss.

 

memo

[WSM]

went into town again today, took my glasses this time. i got the methylene blue and tested my perclorate that i just finished. the water is a very pretty color of blue but no violet or purple. now i have almost a kilo of non percloate crystals. what now ? I am kinda at a loss.

memo

 

Did I understand you correctly? How much methylene blue did you use? By your statement I wonder if you poured a lot into the electrolyte (I hope I misunderstand your description).

 

The methylene blue solution (try 1% solution) is used as a spot test. That means you add one drop of methylene blue solution to a drop or two of suspected perchlorate solution. If it stays blue - no perchlorate. If it turns purple or violet (depends on your perspective) - perchlorate is there. If the perchlorate concentration is low, it may take a while for the positive indication to develop, so have patience.

 

perchlorate test in a spot plate

 

If you were electrolyzing a chloride solution, you likely have chlorate crystals, if it ran long enough. If the chloride level drops to below 10%, you may start to produce perchlorate; and again how long did it run? To go from chloride to chlorate and then to perchlorate is tough work, and can be very hard on a platinized titanium anode (especially if high chlorides are present, as at the beginning), and it certainly takes plenty of time.

 

Did you test the crystals for chlorate? (sodium or potassium, by the way?)

 

WSM

Edited June 5, 2016 by WSM

[WSM]

Pt electrodes don't like ripple on their electricity supply,

 

True, but ripple (AC components [sine waves] in the DC power) can be minimized by adding electronic filtering to the power supply output circuitry.

 

memo said: today I finished up the 3rd run, at room temp I had a bunch of very fine crystals. finer than any of the other runs. I had about 240 hours on this run.

 

I wonder if the platinum is wearing out or being consumed in the process, as happens in industry? This isn't unexpected, especially in a hobbiest scale setup. I use my platinized titanium anodes gently, only in sodium perchlorate cells (sodium chlorate to perchlorate process) and at less than the highest current levels (to see how long I can make my platinum anodes last, and how much perchlorate they can make).

 

For the chloride to chlorate process, my preference is to use MMO on titanium anodes. They last much longer without noticeable wear if using pure water and salts. I also use CP titanium for my cathode plates. The results is usually a clean final product.

 

WSM

Edited June 5, 2016 by WSM

[memo]

wsm I took the crystal and put about 1/2 gram into some ro water. then started with 1 drop of.05 methylene blue. then a few more drops. my anode looks good the stainless steel cathode is taking a beating. I am using ro water in the whole process going to do the sugar and sulfuric acid test later today if it quits raining. I have no other tests at hand.

 

memo

[WSM]

wsm I took the crystal and put about 1/2 gram into some ro water. then started with 1 drop of.05 methylene blue. then a few more drops. my anode looks good the stainless steel cathode is taking a beating. I am using ro water in the whole process going to do the sugar and sulfuric acid test later today if it quits raining. I have no other tests at hand.

 

memo

 

Hi memo,

 

That sounds good. I was worried you dumped methylene blue into a large container of liquid, wasting it (I'm glad I was wrong). I use RO water,too. If you get a chance to buy a TDS (total dissolved solids) meter, you can keep tabs on how your RO system is doing plus compare the resulting filtered water to the tap water. I do that and so far, my RO system removes about 95% of the minerals in my tap water (which runs about 400 ppm).

 

If you add an after filter to the RO system (with the right kind of resins) you can turn the RO into DI water (0 dissolved solids) and run much cleaner electrolysis operations. I'm considering doing that myself (I only hesitate because of the cost).

 

I purchased TDS meters (Pen type) from China on eBay for less than $10 US delivered. They typically come in two to four weeks, but the savings are worth the wait.

 

Let us know how the chlorate test goes, when you can get to it.

 

WSM

[memo]

it quit raining and I got to the shop, took 2 grams of crystal and 2 grams of powdered sugar. put a drop of sulfuric acid and it burned very well took 2 or 3 seconds to burn up. so I would believe that is a positive test for chlorate. I don't know if it is sodium chlorate or potassium chlorate .

 

memo.

[OldMarine]

How do you differentiate between the two?

[memo]

i need to find that out...

[OldMarine]

I did a little search but my chemistry knowledge is very limited [ high school] and I found nothing. This and the other thread on perc cells has me intrigued for some reason.