making potassium (per) chlorate

[Swede]

WSM - good catch on the power supply. Have you had a chance to put it to work? If you need more voltage at the electrodes, you might be able to rig up a remote sense at the straps. What this does - it compensates for the voltage losses in the cable. If the power supply can handle it, you might be able to get another 1/2 volt out of it for perc. But as it is, it should be ideal for chlorate.

[Ralph]

glass can be dissolved(forms sodium silicate i believe) in molten sodium hydroxide it stands to reason that this may happen in a cell full of hydroxide and that it deposits on the electrodes

[pdfbq]

I think it's confirmed glass jars can destroy anodes.

 

I used this nice IKEA jar of 2.2 liters

 

After half a run the current was down to about 8 amps, initially it was about 25 amps.

I already suspected the glass but lately I took a good look at the jar and detected corrosion.

 

Got a new anode from Swede and used a plastic jar this time.

 

After six days run was finished. Dropped in current from 30 amps to 27.5 amp!!

On the left the 'glassed' one (the destroyed one from the first run) and on the right my new DeNora anode after its first run.

Look at the DeNora!!

 

First and for all I want to thank Swede for providing me with a brand new, totally free DeNora anode. Really appreciated!

 

Some notes.

I used another brand of salt and of course this time a DeNora anode.

The reason I'm 99.5% sure it is glass is that my NorthStar anode also suffered from the same problem.

So had this problem two times with two different anodes in two different (but same model and brand) glass jars.

 

edit: added last sentence to notes.

Edited June 26, 2010 by pdfbq

[Swede]

Thanks for those photos. Interestingly, the "silicated" anode really doesn't physically look that bad. I've seen anodes that look worse, but the smut/contamination did not affect current, and was easily removed. Probably calcium or some other salt easily cleaned with water or acids. Have you tried an ohm meter gently across the silicated anode at two points, to see what sort of resistance you get? A clean, new MMO anode should show no more than an ohm or two across 5" of mesh.

 

Given that you've got a good working anode, perhaps a LONG soak of the bad one in concentrated NaOH (days/weeks) might restore it.

 

The current drop of a few amps over a run, with a fixed voltage supply, is (of course) totally normal, given the reduction of ionic species as the solid chlorate forms. Anyway, I'm glad it's all working.

 

Can you tell us about temperatures and yield? 30 amps into 2.2 liters is stout given the volume, and I'd be surprised if it didn't push 80 or 90 degrees C! The evaporation rate must have been very high as well.

[pdfbq]

Can you tell us about temperatures and yield? 30 amps into 2.2 liters is stout given the volume, and I'd be surprised if it didn't push 80 or 90 degrees C! The evaporation rate must have been very high as well.

Cell was an oval 2.2 liter jar submerged in 25 liter of water. Now that one evaporated about 1.5 liter(!) a day but my cell kept relatively cool, about 60C.

Yield: I topped the cell itself with water all the time (about 100cc a day) and after 5 1/2 day the density was ~1.325 g/cm3 (started at ~1.195)

I think that means that 90% of the 600 gram of NaCl has been converted to NaClO3. Did not harvested it yet (its still in solution) but its not the first time I finished a run and normally I get about 700 grams of NaClO3 out of it (I dont think you can get all of the NaClO3 out of the solution, I just reuse it).

Edited June 28, 2010 by pdfbq

[WSM]

WSM - good catch on the power supply. Have you had a chance to put it to work? If you need more voltage at the electrodes, you might be able to rig up a remote sense at the straps. What this does - it compensates for the voltage losses in the cable. If the power supply can handle it, you might be able to get another 1/2 volt out of it for perc. But as it is, it should be ideal for chlorate.

 

Thanks. I haven't put it to work but it's waiting impatiently for me to get going. Thanks for the tip on the remote sense function, I'll have to experiment with it and report the results.

 

I've been on a sidetrack with The Monster. I'm experimenting with a different concept of electrode placement for a continuous system. I have come to possess a bit of thin wall 5" diameter CP titanium tube and configured a piece of Swede's surplus MMO to fit inside the tube section for a cell (see the attached photo, top view).

 

The idea is to weld tubular titanium leads to the sides of the concentric ring electrodes, spaced near opposite sides of the assembly. The whole assembly is to be contained in a vertical section of six inch CPVC with a CPVC plate welded to the bottom of the electrode chamber and a removable CPVC plate lid with a viton seal, friction fitted to prevent salt creep. The two tubular titanium leads are to be solder filled (see Swede's blog) and fitted through PVDF compression fittings in the lid (along with other convenience fittings) and connected to heavy duty leads from the power supply. The short CPVC electrode chamber (EC) will have 1" CPVC side ports above and below the electrodes for fluid flow. The side ports are positioned connecting the EC to the reaction chamber (RC) where the convection-like flow goes from top to bottom and back into the lower port into the EC where the flow is upward; aided substantially by tremendous hydrogen lift and back over to the RC. The liquid level in the EC and RC is maintained constant by a continual pump influx from the crystallization chamber (CC) which is gravity fed from the RC. Quite a mouthful but the diagrams I've posted earlier should make it clearer. The main difference is the electrodes are external to the RC instead of internal (as diagramed earlier for The Monster).

 

In the experimental electrode chamber, the electrodes are spaced from each other by 3/8" OD teflon tube sections held in place by the tension of the anode mesh. Swede suggested I double the effectiveness by having an inner cathode ring (connected electrically outside the cell), and I agree but I want to test it this way first so I can compare the difference. I imagine a lot of activity and heat will result from this type of set up (which is why I plan to use CPVC [rated to 200^o F or 93^o C] instead of the less expensive and more available PVC [rated to 140^o F or 60^o C]).

 

More on this as it develops.

 

WSM

[Ventsi]

That looks spectacular, one question? How did you bend the MMO with out it flaking off?

[WSM]

That looks spectacular, one question? How did you bend the MMO with out it flaking off?

 

Hi Ventsi,

 

I used a low tech solution to solve the problem. I gently but firmly rolled the MMO mesh around a piece of 3" PVC pipe and against an unfinished soft pine board. That got a basic shape. Next, I used hand pressure to gently mold the arc to a tighter circle, which unfortunately, is not as smooth an arc as the original was. I don't suppose the un-eveness of the arc will be a major problem, but it is at least irritating (it's tough having perfectionist tendencies!).

 

Very little, if any MMO came off and the curved mesh looked the same as the flat piece to my eye. I was careful not to sharply bend any portion of the MMO mesh, which would certainly tear or crack the MMO plating. I should probably look at the surface under a microscope to confirm this, but haven't yet (I did this less than three days ago and have been busy since). I need to finish and try the electrodes in salt solution, also. A before and after test of the anode would be a good idea, too.

 

WSM

[Swede]

WSM, after our PM, I took a long skinny scrap of the MMO mesh and bent it as you described. It actually went fine. I was surprised, but I could see no loss of the MMO material.

 

And I'm digging on that configuration. I like the fact that the MMO ends don't meet, so you can increase spacing between the two if you need to. Couple of thoughts: You could use cheap CPVC hot water piping (1/4") to make spaces, and the spacers can be positioned radially rather than longitudinally, as you have. Radially would allow more active MMO surface area. They could be held by the spring tension in the MMO, but I'm wondering if the spring tension wouldn't be lost over time, and over use. Ti under heat and current behaves oddly and can warp. I'm afraid that your spacers could drop out, and you'd possibly get a short.

 

By drilling a few holes in the cathode at the support locations, some sort of stub or pin could be installed that would hold the spacers.

 

Or, you could slot some CPVC pipe sections, and use them to force a regular spacing between anode and cathode, something like this:

 

http://www.5bears.com/perc/tc3007.jpg

 

It's looking good, a really serious setup for production.

[WSM]

WSM, after our PM, I took a long skinny scrap of the MMO mesh and bent it as you described. It actually went fine. I was surprised, but I could see no loss of the MMO material.

 

And I'm digging on that configuration. I like the fact that the MMO ends don't meet, so you can increase spacing between the two if you need to. Couple of thoughts: You could use cheap CPVC hot water piping (1/4") to make spaces, and the spacers can be positioned radially rather than longitudinally, as you have. Radially would allow more active MMO surface area. They could be held by the spring tension in the MMO, but I'm wondering if the spring tension wouldn't be lost over time, and over use. Ti under heat and current behaves oddly and can warp. I'm afraid that your spacers could drop out, and you'd possibly get a short.

 

By drilling a few holes in the cathode at the support locations, some sort of stub or pin could be installed that would hold the spacers.

 

Or, you could slot some CPVC pipe sections, and use them to force a regular spacing between anode and cathode, something like this:

 

http://www.5bears.com/perc/tc3007.jpg

 

It's looking good, a really serious setup for production.

 

Hi Swede,

 

Thanks for the thoughts. I was surprised too, but gratified as well, that it worked out. I like your idea of using CPVC instead of that expensive PTFE! That's a good idea. I'm not stuck on my spacers and may well change the configuration as needed, but I also like the idea of fixing them to the cathode plates to prevent shorting the electrodes. Maybe I should get some CP titanium wire to hold the spacers in place. I want to minimize any obstruction to the vertical fluid flow, which I'm depending on to keep things moving between the EC and RC. Thanks also for the warnings about warping. I wouldn't want to see that in this system (plus the untold damage to the power supply )!

 

The attached photo shows more of the parts I was preparing for the EC. The heavy tube was supposed to be CPVC but unfortunately wasn't (I'm still looking if anybody has some schedule 80, 6" CPVC pipe to spare). Lucky I didn't already glue it to the 1/2" CPVC plate before I discovered the error. I threaded the ID of the 1/2" titanium tubular leads and inserted stainless bolts for connecting leads from the power supply. I plan to cut the length of the bolts to a closer fit in the tubes. I also plan to heat and flatten the other ends, preparatory to spot welding them to the titanium cathode and the MMO anode rings. I will fill them with a low temperature alloy to make the tube leads more conductive, so heating won't be an issue for the PVDF compression fittings used to hold the electrodes in the lid of the cell. The photo shows the heavy wall PVC pipe section and everything is layed out on a sheet of PVC (not the CPVC) for a background.

 

WSM

Edited June 30, 2010 by WSM

[50AE]

Guys, I found a cheap Pb(NO3)2 source and I think I'm gonna be plating PbO2 anodes, if my last MMO from Swede dies. For now, it's doing ok and I'm keeping an eye on the cell. No electricity stops for now and I always turn the cell off when I'm not at home.

[Ventsi]

The good news- after five days I got 1/2lb of nice pure KClO3, I didn't even bother to extract all of it either.

 

The bad: I ruined two shirts because of the solution getting on them, F&^$K!!

[50AE]

Oh yeah, be careful. I ruined one pair of jeans and one shirt.

[Arthur]

A good lead dioxide anode is one good way through to perc even supposedly in a single stage.

 

Now if you have good chlorate with a MMO cell, you could perhaps use a lead dioxide electrode in a separate cell for the ClO3 to ClO4 stage. Then you can always purify the separate products and send the waste back into a previous cell.

[WSM]

Oh yeah, be careful. I ruined one pair of jeans and one shirt.

 

Well,...yeah. That's why they call it "bleach".

 

Fundamentally the KCl + H₂O + e -> KClO + H₂^. KClO looks like, smells like and acts like NaClO in most every sense and we need to remember this and act accordingly. Safety first folks!

 

WSM

[50AE]

I knew it's bleach. But I have a default in my life - sometimes I'm lazy to change clothes, thinking dirt and chemicals will not get to me.

But I now always change clothes since I ruined a 20$ pair of jeans with sulfuric acid

Edited July 5, 2010 by 50AE

[WSM]

I knew it's bleach. But I have a default in my life - sometimes I'm lazy to change clothes, thinking dirt and chemicals will not get to me.

But I now always change clothes since I ruined a 20$ pair of jeans with sulfuric acid

 

 

I guess my statements were rhetorical. We all know that smell (bleach, I mean). Still if we know this we ought to protect ourselves and our property from damage with it. I guess I'm cheap and so I'm careful not to destroy my clothes with the stuff (let alone my skin). I'm glad you've learned from the experience. I'll tell you how I burned my moustache off once, a long time ago; but that's a story for another time...

 

WSM

Edited July 6, 2010 by WSM

[dagabu]

I'll tell you how I burned my moustache off once, a long time ago; but that's a story for another time...

WSM

 

OK, now I have to hear that one

[Mumbles]

When working with bleach it's inevitable to ruin a few shirts. I was working with thiophenols last summer. They smell god aweful, and the way to decontaminate is to wash with bleach (oxidizes it to sulfones which are generally solid and smell less bad). Eventually you learn to just wear white shirts. A similar thing happens if you use benzoyl peroxide face wash. It inevitably gets onto a towel or shirt or something like that. It doesn't do anything at first, but if you wash it in warm water you'll get bleach splotches appearing.

[WSM]

OK, now I have to hear that one

 

 

This is probably one for the safety section, but okay, here goes:

 

Many years ago (more than twenty) I had thought of mixing collodion (low grade NC in ether/alcohol) with FFFg black powder (I can't recall now, why at the time I thought that was a good idea or what I planned to do with it). I had stored about half a film-can-full for quite a while when I decided one day to get rid of it. My mind wasn't on what I was doing since I had just had a dissagreement with my wife. I dumped the goop out on a piece of paper and set it on the ground when I lit a match and dropped it near the pile (I was unwisely standing over the pile).

 

Whoof!!!, a great fireball rose up and my reactions were fast enough for me to immediately turn my head away... but not quick enough. My nice handlebar moustache turned into a "Clark Gable" instantly. Whoa, that was close AND I felt a LOT of heat in that instant. I put things away quickly and went into the house where I told my wife what happened. I still felt the heat on my face and decided to shave the remnants of my moustache off to fully survey the damage. It was not too bad but still tingled and was tender, and I could see some blistering beginning to show in a few small spots on my face.

 

At my wife's urging we went to the emergency room where she unloaded on the attending physician, "He's always messing with that stuff (fireworks), how do you get a guy to quit messing with that stuff?", and the doctor stared at her and said, coldly; "Exorcism."

 

The above story is all true, (you can't make this stuff up) and I have never published it publicly before this. Fortunately, she never found an exorcist .

 

WSM

[dagabu]

 

At my wife's urging we went to the emergency room where she unloaded on the attending physician, "He's always messing with that stuff (fireworks), how do you get a guy to quit messing with that stuff?", and the doctor stared at her and said, coldly; "Exorcism."

 

WSM

 

Bwaaaaa-Haaaaa!!! :lol: Exorcism, I love it!!

 

My wife is a pyro too, guess we both got it bad huh?

 

Thanks for the story.

[WSM]

Hi All,

 

Swede asked that I show the attached photos of a PVDF filter housing I acquired on eBay recently. The photos show the physical dimensions and the great good fortune of having a socket in the inside lid which is a tight fit for some 1.750" OD CP titanium tube I got in 2008. I simply have to make a cell incorporating this unit! I haven't given up on the other projects but this piece is calling to me! We'll see where I go with this. The ports on this housing are 3/4" NPT and the accessory ports are 1/4" NPT so plumbing this jewel will be easy with PVDF tube fittings. More about this later; I've got to get back to The Monster.

 

WSM

[WSM]

Hi Everyone,

 

I did some more work on the concentric electrodes and learned several things. Swede expressed the opinion that it was best to remove the MMO from the titanium mesh on the eBay anode material before spot welding the titanium leads on. I tried it without removing the coating and it worked just fine, though it took a little longer than when the MMO was removed. I work outdoors so I'm not as concerned about vapors of ruthenium, etc. (hold breath and go for it!).

 

I flattened the ends of the tubular leads the way Swede described in his blog. I used a propane torch and heated the end of the titanium tube without sweeping back and forth (like I usually do when trying to heat something for brazing or silver soldering), just direct the flame at one spot and blast away until it gets to red heat, then turn the tube slowly to let the end get completely red. Next I start flattening the end on a one ton arbor press against a piece of 0.750" thick steel plate. As Swede says, do this in several steps so the tube doesn't split on the edge. When the end of the tube gets to a flat "infinity" symbol shape I change the technique a bit. I heat the tube end to red heat again and then tap the flattened part against an anvil with the flat end of a ball peen hammer. I do this carefully to keep the surfaces flat and make a better welding surface. After this, I cool the piece and test it for a good seal; I blow through the tube into a glass of water and look for bubbles (see bubbles, heat and pound again; no bubbles = success!).

 

After I flatten the ends of the lead tubes, I buff off the oxides so I get a better resistance weld. I clamp the two pieces to be welded tightly in the welder and apply the current until the welder starts to "complain" (Growl) and starts to show a red glow around the points of contact. The weld tends to be very good when I do this.

 

Now that the electrodes have the leads welded on, I need to fill the tubes with conductive metal so the resistance of the leads is reduced; keeping them cool so they don't adversely affect the plastic compression fittings (PVDF) holding the leads in the lid of the cell. I'll probably fill them with solder, except for the last bit in the top end. The tops of the lead tubes are tapped to accomodate stainless steel bolts for connecting the power leads to the electrode leads. I have some close fitting 316 stainless washers that just fit on the stainless bolts, to clamp on the power lead spade terminals.

 

Now that I've come this far, I need to dissolve some KCl water softener salt and test these babies out .

 

More later...

 

WSM

Edited July 10, 2010 by WSM

[WSM]

A good lead dioxide anode is one good way through to perc even supposedly in a single stage.

 

Now if you have good chlorate with a MMO cell, you could perhaps use a lead dioxide electrode in a separate cell for the ClO3 to ClO4 stage. Then you can always purify the separate products and send the waste back into a previous cell.

 

Hi Arthur,

 

I have to agree and that's the way I see it too. Separate cells for each stage, KCl to KClO₃ then KClO₃ to KClO₄. I'm still not sure whether to plan on using platinized titanium or LD plated MMO for the second step. When I have a good feed stock of chlorate I'll have to step up and choose one of them to continue the process of perchlorate production (and independence ).

 

WSM

[WSM]

With the concentric electrodes prepared and ready to go I decided to try a test cell. Since the schedule 80 tube was PVC (instead of CPVC) I used clear PVC for the bottom and lid of the cell in lieu of the expensive CPVC plate. It came together well and machined easily. I have to drill and install ports for flow into and out of the electrode chamber, but the basic form is visible in the photos below.

 

If I glue a short section of PVC pipe in a PVC union and install it in the electrode cell, it allows a means of disconnecting the EC from the RC (reaction chamber).

 

More later...

 

WSM