making potassium (per) chlorate

[pdfbq]

@Bikemaster

Attached another closeup which shows imho it is something on the still intact MM layer.

 

voltage 5.2V

space between anode and cathode 4cm (1.6")

max amps I had 16A

used only 2 runs in a 2 liter NaCl cell.

Cathode Ti mesh (so TiO2 can come from the cathode)

 

Today I will have it in boiling water for some time as mumbles suggests

Edited April 9, 2010 by pdfbq

[50AE]

It is possible that the fluoride from the tap water has contaminated the MMO? Our water contains 1.5mg/L F

[bikemaster]

Well... that don't seem to be erosion and it is not looking like my anode too.

Also, you only do two run in not so hard electric condition. I don't know what you have in your water or you salt, but it seem to play a role. Did you know what is the grade and de composition of the cathode (aluminium and magnesium content).

About fluoride, this is and other bright thought, because it attack titanium substract anode.

 

Quote from Dann22 web site:

 

"Fluoride in the form of Sodium Flouride plays a similar role to Chromate and is compatible with Lead Dioxide. Fluorine also raises the Oxygen over-potential at the Anode (less Oxygen gets produced) giving greater CE in both Chlorate and Perchlorate production. Several sources have stated that Titanium Substrate Lead Dioxide Anodes and also MMO Anodes can be damaged by Fluoride containing electrolyte, therefor Fluoride is not recommended when using Ti substrate Anodes.

Persulphate is also said to increase CE with Lead Dioxide."

 

 

 

 

[Arthur]

Swede, you've done lots of electrolysis without these problems IS your tap water fluoride treated?

[Bonny]

I just made some better connections for my cell. Found some thicker wire and used it as well. It's looking much better now.

 

That looks great TBP.

 

Swede, you've done lots of electrolysis without these problems IS your tap water fluoride treated?

 

I know my tap water has flouride in it, and a host of other crap I'm sure, but I have only ever used distilled or filtered water bought from water stores.

[Swede]

Swede, you've done lots of electrolysis without these problems IS your tap water fluoride treated?

 

Yes it is. I have never had these problems. I use plain tap water and commercial hardware-store KCl nuggets.

 

Usually, the issue (when MMO becomes problematic) is excess voltage which breaks down the conductive layer of MMO over Ti. MMO costs a bunch because the process of coating the Ti with the MMO slurry is a proprietary process... those that do it, keep their process relatively secret. Ti behaves a lot like aluminum. Bare Ti immediately forms an oxide skin that is non-conductive. When the MMO factories take their Ti mesh, they treat in in some manner to strip all oxides off (perhaps electrolytically), and it is immediately dipped into the MMO slurry, or the slurry is sprayed on. It might even be done in an oxygen-free environment, but more likely, it is a liquid process. The slurry is then baked, and there is solid conductance between the Ti and the MMO layer.

 

Either way, excess voltage is death to an anode, because it breaks through bare Ti oxides which normally protect the metal, and erosion results. It also can trash the conductive interface between the Ti and the MMO layer.

 

Another possibility - MMO formulations vary. Some are optimized for the chlorate process, others for different duties. The Ruthenium Oxide percentages can vary, other compounds added, and they may not all be compatible with the chlorate process.

 

If those white xtals do not come off in either boiling water or HCl, then whatever they are, they are damned inert. While ugly, do they inhibit the functionality of the anode? Perhaps a careful mechanical attack on them may help, like a dental scaler. I have no other ideas.

 

50AE buddy, I don't know what's going on. PM me, we can set something up, perhaps with a DeNora anode.

 

WSM, The Monster is going to rock! I'm glad you are starting to document. Take plenty of notes - what seems fresh now in your mind will definitely not be in a year or two. I hope you are able to solve all of the issues that a two-celled operation present, and if you can figure out a way to close the pH loop, you will be a hero to all hobbyists. One good notion is that 3M KCl solution is an excellent probe storage media - how convenient is that? If you can cycle the probe periodically with an automated system that samples, then adds 3M KCl into the pH electrode chamber, then it should survive. Obviously, it cannot be allowed to dry out, so it must be in the 3M KCl most of the time, when it is not sampling the liquor. But if it fails or becomes too much of a hassle, rest assured that mathematically-derived HCl delivery does work very well, and is not hard to do. Once the chemistry stabilizes, there is some sort of a buffering action that takes place, and the system is relatively stable. I think 6.8 +/- 0.5 pH is more than adequate, and that is a wide range. It is not difficult to get it within +/- 0.20.

 

I wanted to mention - polypropylene fittings will die quickly, and silicone will harden; generally will do OK, but not indefinitely. I recommend PVDF fittings and Tygon R-3603 if you need flex tubing. Obviously PTFE works too but is expensive. On a nit-picky side, the buna-n o-rings in your PVC couplers might need replacement (eventually) with viton. Otherwise, it's looking awesome. When you need a dedicated stand for the collection chamber, you know you are going big. I'm looking forward to your results! Start a blog!

 

It's been a while, but I did add another blog entry, the T-Cell III. Just basic improvements to the previous system:

 

http://www.5bears.com/perc/tc3001.jpg

 

I've also got that bulk Pt over Ti mesh that is dying to be made into an anode or four. Finally, the tubular Ti shanks filled with tin or some lead alloy does work well. I think the Pt anodes will definitely get the deluxe shanks.

[bikemaster]

This is a real piece of art!!! Can't wait to see what will be the yeild.

 

The question may seem stupid, but what is killing the Ph prode? The current that pass in the solution or the solution itself.

[TrueBluePyro]

Here is a video of the new cell of mine if anyone is interested.

 

 

Or you can watch it here...

 

[WSM]

That looks great TBP.

 

 

 

I know my tap water has flouride in it, and a host of other crap I'm sure, but I have only ever used distilled or filtered water bought from water stores.

 

 

In my area I learned they fluoridate the water with addition of fluorosilicic acid. If they use the same material where you are, could silicates be forming on the MMO? Just a thought.

[WSM]

The basic concept of the monster is drawn up as a diagram and I'm attaching it below. The diagram is basic and omits all the attendant plumbing and other connections for clarity. I am still debating whether to have the electrode chamber internal or external to the reaction chamber. My thought is to make it initially internal and see how that works. If there are problems with internal placement, then modify the system to one with an external electrode chamber. I have an excellent design waiting in the wings for an external EC.

 

Since heat is our friend in the reaction chamber (> 40 up to 70 degrees C), if neccessary, insulation will be attached to the exterior to retain as much heat as possible. This should help keep the formed chlorate in solution till it is dispersed in the crystallizer, where it is designed to drop out.

 

I will monitor the temperatures of the reaction chamber and the crystallizer (we need the crystallizer to be between 20 and 30 degrees C or too much of the chlorate will stay in solution; too cool and KCl will drop out too )

 

 

pH control will be by dilute HCl injection utilizing a surplus metering pump purchased on ebay, through PTFE tubing (also from ebay) as deep in the reaction chamber as I can get it. The hope is that any chlorine gas developed will stay in solution and not bubble out . Again, I'm working on a method of active pH control but I plan to go ahead with this project with timers first and add in active control when/if I succeed with it. Thanks again to Swede and others for cheering me on in this effort. More on this later...

[pdfbq]

Guys,

 

I think I fixed my anode. As Swede suggested I took a mechanical attack on it by rubbing the anode with a cotton cloth and with a paper tissue.

I expected some MMO material on the cloth and tissue but I did not see any so that was nice.

Not all the white stuff came off but enough to have a low resistance when testing with a multimeter.

 

It's back in a cell warming up now. Seems to work again, It's on 12A already!

 

P.S We don't have fluor in our tap water.

Edited April 10, 2010 by pdfbq

[Arthur]

As you are creating a continuous salt removal system (OK chloride in chlorate out) you will need to monitor the chloride level in the electrolysis cell. It's seriously important to keep the chloride level up, it improves cell conductivity and protects the electrodes. Obviously as it runs you can develop empirical methods and reduce the number of tests needed

[Bonny]

I just shut down my perc cell after the 3rd (and last I think) run with my second Pt anode. It looks pretty eroded, but I'll have a better look once the cell is disassembled. It seems, oddly though, that the anode erodes far worse on the side facing away from the cathode, where no current should be flowing...

 

I started with 1900g KClO3, but I did use some feedstock that was washed only, as I ran out of recrystallized stuff. I ran the cell for 91hrs x 8.5-9A (roughly), so about 800ah.

The crop looks good and is chilling as we speak to get as much out of the liquor as possible before further processing.

 

I have included a few pics of my set up. The green hose is for the (aquarium) bubbler, which really helps keep the cell temp more even top to bottom. The power supply is a battery charger running ~9a @ a little over 5V. I still use the battery charger (for batteries), so that's why the clamp connections weren't removed,

 

In the electrode pic you can see that the anode is pretty much bare of Pt (light colour). I hope the other side looks better.

[WSM]

I just shut down my perc cell after the 3rd (and last I think) run with my second Pt anode. It looks pretty eroded, but I'll have a better look once the cell is disassembled. It seems, oddly though, that the anode erodes far worse on the side facing away from the cathode, where no current should be flowing...

 

I started with 1900g KClO3, but I did use some feedstock that was washed only, as I ran out of recrystallized stuff. I ran the cell for 91hrs x 8.5-9A (roughly), so about 800ah.

The crop looks good and is chilling as we speak to get as much out of the liquor as possible before further processing.

 

I have included a few pics of my set up. The green hose is for the (aquarium) bubbler, which really helps keep the cell temp more even top to bottom. The power supply is a battery charger running ~9a @ a little over 5V. I still use the battery charger (for batteries), so that's why the clamp connections weren't removed,

 

In the electrode pic you can see that the anode is pretty much bare of Pt (light colour). I hope the other side looks better.

 

Hi Bonny,

 

Do you think you would get even wear on the anode if you used two cathodes (one on either side of the anode and connected in parallel outside the cell)? I was considering trying a small trial cell for KClO3 > KClO4 and will post results whenever I get around to setting it up. How thick was the Pt layer if you know? Thanks for sharing your experiences.

 

WSM

[Bonny]

Hi Bonny,

 

Do you think you would get even wear on the anode if you used two cathodes (one on either side of the anode and connected in parallel outside the cell)? I was considering trying a small trial cell for KClO3 > KClO4 and will post results whenever I get around to setting it up. How thick was the Pt layer if you know? Thanks for sharing your experiences.

 

WSM

 

I would think the wear would be more even with 2 cathodes. I did this with my first (tiny) Pt anode. That anode only made it through 2 runs (1 small test and 1 other run). I think I ran it too long that time, but both sides were eroded. As for the anode, I'm not sure how thick the Pt layer was, it is an (Ebay) jewellery trade anode, take a look there, other than Northstar Pyro, it is the only other commonly available.

[pdfbq]

is an (Ebay) jewellery trade anode, take a look there, other than Northstar Pyro, it is the only other commonly available.

I have them both. The Northstar is $79,- and the one from Bangkok $29,-

The Northstar already survived 3 runs of making NaClO4 (after chemical destruction ClO3, double replacement and recrystallization total 1800 grams of clean KClO4).

The Northstar stil looks OK to me. Is a different technique than the Thai anode. Northstar looks like the platinum anodes swede bought but is VERY small, 1/2" 4".

I'm running the little Thai anode now. This has a very thin layer of pure titanium (i think). They both do 5A over 5.2V which is enough. Converts in 4-5 days about 650 grams of NaClO3 to NaClO4

Edited April 11, 2010 by pdfbq

[Bonny]

I have them both. The Northstar is $79,- and the one from Bangkok $29,-

The Northstar already survived 3 runs of making NaClO4 (after chemical destruction ClO3, double replacement and recrystallization total 1800 grams of clean KClO4).

The Northstar stil looks OK to me. Is a different technique than the Thai anode. Northstar looks like the platinum anodes swede bought but is VERY small, 1/2" 4".

I'm running the little Thai anode now. This has a very thin layer of pure titanium (i think). They both do 5A over 5.2V which is enough. Converts in 4-5 days about 650 grams of NaClO3 to NaClO4

 

I think it is "easier" on the anode doing it that way- NaClO4, as the NaClO3 csolubility and concentration is much higher and you are (less) likely to run it too low. I have only been working with potassium salts.

My 6 x 5cm anode (she will make a single pc instead of 2 - 3 x 5 pcs) survived 3 runs with current as high as 12A. But now has been eroded to uselessness. The batch of raw "dirty" perc looks to be at least 1kg...hopefully closer to 2kg.

[pdfbq]

My 6 x 5cm anode (she will make a single pc instead of 2 - 3 x 5 pcs) survived 3 runs with current as high as 12A. But now has been eroded to uselessness. The batch of raw "dirty" perc looks to be at least 1kg...hopefully closer to 2kg.

I know, for the money we should not do this but 2 kilo's and anode dead... ouch. I will keep using my Thai anode in the NaClO3 environment. See how long it will last in a sodium chlorate environment.

[Bonny]

I know, for the money we should not do this but 2 kilo's and anode dead... ouch. I will keep using my Thai anode in the NaClO3 environment. See how long it will last in a sodium chlorate environment.

 

I know it's definitely expensive, but in my case I have no other access to perc so it's a necessary expense. I am considering going to chlorate for certain things, as I have an abundance of that and it is very easy to make.

 

When I get another anode (won't be very soon) I'll probably try to do things a little different. Maybe lower the current, as well as watching cell temp that I suspect might have been too high.

Anyway, as soon as I get myself in gear, I'll be doing some clean up tests, first step is to dissolve/filter and re-xstallize 2-3 kgs of dirty perc that I now have.

[50AE]

But how can tap water be the reason, when these MMO are designed to chlorinate pools and I doubt distilled water is put there?

 

Today I broke the cell's lid seal, to take photos of the MMO anode, dead vs new one. The dead has some very light gray spots, like if the MMO has become transparent, so we can see the titanium:

 

http://img690.imageshack.us/img690/5596/mmoside1.th.jpg http://img260.imageshack.us/img260/9387/mmoside2.th.jpg http://img515.imageshack.us/img515/3421/mmoflash.th.jpg

 

Maybe the MMO has really erroded?

Also I didn't specify one thing:

-In my country, the electricity can be very shit. The motherfuckers turn the power off of the neighbourhood sometimes, and maybe I'm sleeping or I'm not in home during that. Maybe the cell anode acts like a battery and puts current back to the power supply, which maybe errodes the MMO. Also, MMO staying without power in the cell might not be a good idea. I will do an alternative power supply circuit, and I'll also place a welder diode in series.

[FrankRizzo]

Bonny,

 

Regarding your platinum erosion problem: Most battery chargers have a significant AC ripple, which in the cast of battery charging doesn't make much difference. If the polarity is swinging, the platinum will dissolve.

[TrueBluePyro]

With my new 10L cell, after a few days when I got all the connections right (crimped copper pipe), I produced about 50 grams of recrystallized product first time round. The next day I check it agian and got the crystals out and got about 200 grams or recrystallized product. Did the same thing the next day and got 490 grams of unrecrystallized (didn't have time to recrystallized it) and then I had to stop because I went back to school and couldn't leave it running without my attention.

 

So around half a kilo a day isnt bad once it is running nicely.

 

Also, I just bought a 25 kilo bag of kcl for about $65 (aussie dollars), so that isn't too bad. I'll start pumping more kclo3 out once I get home.

[Bonny]

Bonny,

 

Regarding your platinum erosion problem: Most battery chargers have a significant AC ripple, which in the cast of battery charging doesn't make much difference. If the polarity is swinging, the platinum will dissolve.

 

Thanks Frank. That's good to know for future reference, but for now I'm out of anodes . I think If I get another I might look into a better power supply, maybe even using a PC power supply. The 5V setting should work, and I think there's a way to get ~7V from them. Anyway, I'm done with making perc for now, most likely until next fall/winter. I have several kgs of dirty perc to clean and that should last me through the summer.

[Swede]

WSM - looking at your "Monster" system, I don't remember, but do you have a lid for the xtallization chamber? I believe you mentioned that you did, which is a good thing, otherwise, the fumes would be absolutely brutal and probably make a room dangerous.

 

Have you given any more thought to pH? Even the simplest possible system that I can think of would require a pump for the liquor, another pump + vat for 3M KCl, OR... a mechanized system that will lift the probe clear of the KCl, dip, measure, then return to the pure KCl.

[WSM]

WSM - looking at your "Monster" system, I don't remember, but do you have a lid for the xtallization chamber? I believe you mentioned that you did, which is a good thing, otherwise, the fumes would be absolutely brutal and probably make a room dangerous.

 

Have you given any more thought to pH? Even the simplest possible system that I can think of would require a pump for the liquor, another pump + vat for 3M KCl, OR... a mechanized system that will lift the probe clear of the KCl, dip, measure, then return to the pure KCl.

 

Hi Swede (and everyone),

 

Oh yes, a lid for sure. I did discover that since the lid is so big I think I'll have to add ribs to the top of it to reinforce it and prevent sagging. I plan to vent it too (same as the reaction chamber but mostly for fumes, not H2). I have given thought to the pH system. I have slowly acquired some pneumatically actuated PTFE valves through ebay and have considered using some to valve the test chamber for active pH control. One trick will be keeping the plumbing at the same warm temperature as the reaction chamber to prevent crystals dropping out and jamming the pH testing chamber or the valves themselves (which would be disasterous). I like the idea of an isolated test chamber inside the reaction chamber that inserts liquor into the test chamber, tests it and purges the liquor out with fresh salt solution, the same makeup solution used to replenish the cell as the chlorate depletes the chloride levels (it's not much stronger than a 3M solution, but if you feel a 3M solution is best I can do that instead). I want to avoid putting the sensitive (and expensive) pH probe in an active chlorate cell, with all it's chemical and electrical nasties if I can help it .

 

As for pumps, I have a few; both metering pumps and peristaltic pumps. I have also built a few PVC diaphragm pumps plus the attendant gear to run them; and they aren't out of the question either. I followed the pattern a friend developed on those. I just haven't figured out the best way to apply them yet, but I'm working on it. I'm almost afraid I'm having more fun figuring out the problems and building the system than I will producing my own oxidizers . I think routine production will be mundane after all the bugs are worked out .

 

Then again; turning surplus chlorate to perchlorate! Ah, now there's a worthy challenge . I haven't even begun that phase yet! I'm sure I'll be tinkering for years to come!

 

As to the active pH control problems, any suggestions from all are welcome. You never know which nugget of thought will be the inspiration that will help overcome a sticky problem in the process. Thanks in advance!

 

WSM

Edited April 16, 2010 by WSM