The Bucket Cell - Start to Finish

[WSM]

To reuse the depleted perchlorate cell liquor (if it's from a cell which had the residual chlorate destroyed by sodium metabisulfite), consideration should be given to removal of unwanted ions before recharging with chlorides and running it in a chlorate cell.

My first choice has been removal of sulfates with calcium chloride, being careful to remove all calcium salts before use in a chlorate cell. Remove any remaining calcium ions with a very slight excess of sodium sulfate solution and filter out the insoluble calcium sulfate before adding sodium chloride to replenish the chlorate cell electrolyte.

This should work.

WSM

Edited September 16, 2015 by WSM

[WSM]

My thoughts on trapping sodium inside the crystal had more to do with the speed at which it's being precipitated, not necessarily the size of the crystals. Being so instantaneous, things could get caught sort of in essence because it can't get out of the way fast enough. I guess there's only one way to find out. Keep us posted.

 

Mumbles, it looks like you're right.

 

My initials flame tests seem to indicate there may be some sodium salts residue clinging to the potassium perchlorate crystals. My first inclination is to try multiple washings with distilled water while the crystals are in the Buchner funnel (with the vacuum source running), then dry and test the potassium perchlorate.

 

It would be nice to have a specific spot test for sodium that worked in the presence of potassium and other ions, but I haven't found one yet.

 

I may just process the rest of my sodium perchlorate solution into solid (powder) potassium perchlorate, and then rinse the crystals with several washings of distilled water till they're "sodium-free", or indicate no sodium contamination at all.

 

Edit: I wonder if drip feeding the KCl solution slowly into the NaClO₄ solution would help avoid sodium contamination of the fine potassium perchlorate crystals formed? I don't know and may have to test the idea. Since sodium salts are generally so much more soluble than the potassium perchlorate, unless they're trapped inside the KClO₄ crystal matrix, fresh water rinsing should remove them.

 

I really want avoid dissolving and recrystallizing the potassium perchlorate crystals, which would take much more energy (and drive up the cost of my home grown perchlorate).

 

We'll see...

 

WSM

Edited November 9, 2015 by WSM

[Mumbles]

There are some ways to slow down the crystallization without doing anything all that special. If you slowly pour a solution of KCl onto a solution of NaClO4, it will slow down diffusion and often results in larger crystals. Think almost layering one solution onto another. This is most easily done with a larger container. I like to tilt the container, and smoothly pour the second solution down the wall. If you do this in a clear container, it almost looks like it's snowing crystals.

 

I'm again just thinking out loud here. Ideally the crystals will form well, and residual sodium will mostly just be adhering to the crystal surface.

[Arthur]

The method of adding the KCl governs the precipitation speed and the size of the crystals. Smaller crystals are easier washed.

[WSM]

The method of adding the KCl governs the precipitation speed and the size of the crystals. Smaller crystals are easier washed.

 

Hmm..., it seems Mumbles had just said something to that effect. Basically you're both right, and I really like what Mumbles said about slowly adding the KCl solution so the two liquids have a large shared surface contact area where the KClO₄ will form at a controlled rate (like snowflakes dropping out).

 

Another electrochemist friend mentioned, rather than simply rinsing the crystals in a Buchner funnel with distilled water; soak the crystals in a larger volume of distilled water and then vacuum filter the KClO₄ crystals, so the soluble sodium contaminants will be diluted and washed away at the same time. This makes a lot if sense to me, and will probably work much better than just multiple washings. I wouldn't be surprised if that's something industry might do for a purer end product.

 

The soaking water (filtrate) can be used for subsequent system water replenishment, so any dissolved perchlorate isn't wasted but used and harvested later. I like it!

 

WSM

Edited November 27, 2015 by WSM

[pyrojig]

Is there a way to get Na perch out of solution as a solid with out too much trouble ? I know it is very thirsty for water.

[WSM]

Is there a way to get Na perch out of solution as a solid with out too much trouble ? I know it is very thirsty for water.

 

I think it can be had as dry crystals, but, as you mentioned it's attraction to water, I don't think it'll stay that way for long.

 

If one heated a purified solution of sodium perchlorate to concentrate it by driving off the water, I think the end result would be dry, solid crystals. A highly active desiccant present would be required to keep them dry, Though.

 

Why do you want sodium perchlorate crystals?

 

WSM

[pyrojig]

Dont really need dry Na perch, just curious how it is sold commercially.

[50AE]

My first photos of making of my 5L bucket chlorate cell with Ti/MMO electrodes:

 

 

The top plate is from textolite. I had a small piece from my scrap storage. At first, I tried to cut the disc using a hole saw, but it was too "cheap" for a material like textolite. The disc was too small to cut for my router too. So I cut it with an angle grinder . Then I smoothed it by turning it with my drill press and sanding it with some 60# grit.

 

The tiny cuts for the electrodes were a bit of pain, but I figured them out - dremel + small saw + sandpaper combo. I did very tight, hermetical cuts, avoiding any need of glue.

The electrodes keep themselves at an uneven distance, but this was expected. Tomorrow I will make some PVC spacers. Or screws (better). If I find a bit of PVC rod, I will cut some threads in them.

 

Next I need to buy vent hose and screws for it.

By the way, is it okay to screw the lid with stainless steel bolts?

Edited December 3, 2015 by 50AE

[WSM]

My first photos of making of my 5L bucket chlorate cell with Ti/MMO electrodes:

IMG_20151203_150845283.jpg

IMG_20151203_164415195.jpg

IMG_20151203_164425220.jpg

The top plate is from textolite. I had a small piece from my scrap storage. At first, I tried to cut the disc using a hole saw, but it was too "cheap" for a material like textolite. The disc was too small to cut for my router too. So I cut it with an angle grinder . Then I smoothed it by turning it with my drill press and sanding it with some 60# grit.

The tiny cuts for the electrodes were a bit of pain, but I figured them out - dremel + small saw + sandpaper combo. I did very tight, hermetical cuts, avoiding any need of glue.

The electrodes keep themselves at an uneven distance, but this was expected. Tomorrow I will make some PVC spacers. Or screws (better). If I find a bit of PVC rod, I will cut some threads in them.

Next I need to buy vent hose and screws for it.

By the way, is it okay to screw the lid with stainless steel bolts?

 

I expect your stainless steel bolts will see corrosion from the mother liquor (and might possibly introduce chromium, iron and nickel ions into the solution if in contact with cell fluids). If you can insulate/isolate the stainless steel from the cell liquids, then it should work out fine.

 

Good Luck.

 

WSM

[WSM]

Dont really need dry Na perch, just curious how it is sold commercially.

 

I don't know but possibly "dry" with powerful desiccants added. Remember, sodium perchlorate isn't merely hygroscopic; it's deliquescent!

 

WSM

Edited December 4, 2015 by WSM

[pyrojig]

I only ask because I read a few patents in past and wondered about how they utilized Na perch ( as a solid or a s in sol. )for an emulsion .It may be another discussion for the HE section .

[WSM]

By the way, is it okay to screw the lid with stainless steel bolts?

 

I reread what I wrote, and upon further consideration, If the exposed stainless steel is protected it should pose no problem. I see it this way:

1. it's on the lid of the bucket cell
2. the exposed metal can be covered with silicone sealer (which will adhere better if the surface is rough)
3. it's good practice to leave a space above the liquor for the H₂ bubbles to pop (and minimize salt creep)
4. the "textolite" board appears to be fiber reinforced phenolic or epoxy board and is better above the liquor also (not in contact with it)

By all means, give it a try. I like the different approach and your adaptation using the materials available to you (very creative).

 

As you get further along with this project, please continue showing your progress with photos and descriptions (and THANK YOU for sharing!).

 

WSM

[WSM]

Lately, I was bemoaning the lack of surplus MMO anode material on eBay, when I checked and SURPRISE!, laserred currently has three applicable listings for his used MMO stock.

 

The three sizes are:

1. a set of six pieces of 1" x 10" long MMO mesh for auction
2. a 3" x 6" piece of MMO mesh
3. a 3" x 10" piece of MMO mesh

I have probably a multiple lifetime supply, but it's good to see it still available for others to enjoy.

 

WSM

[WSM]

I was searching online for MMO and found a new source for used material. It's solid plate CP titanium coated with MMO. The sheets are 1/16" thick and 4" wide by >16" long and plated about half their length with MMO.

 

A little quick math and I calculated the maximum current draw of one of these anodes to be over 120 Amps if surrounded with cathodes! I'm sure this material can be cut with a hacksaw to smaller sizes.

 

This material is reasonably priced as well, at $15 plus $3 shipping.

 

I bought some to try out and they look good. I'll test them soon and report here on the results.

 

WSM

Edited March 17, 2016 by WSM

[WSM]

I tried them and I approve.

 

 

I used my monster new power supply, set it for CC mode and drove the bottom half of one anode and one cathode to 31 Amps. It was placed in 3 liters of KCl solution which worked well and immediately produced hydrogen and a chlorine smell... Success!

 

I can see these electrodes being used for large production machines (for hobbyist sized setups).

 

The power supply will work for almost any chlorate or perchlorate cell experiment I might want to try. It's a winner!

 

WSM

Edited March 20, 2016 by WSM

[WSM]

The MMO flat sheet anodes are available on eBay (Item number 222043186779) for $15 each. Shipping is $3 for the first one and $1 each for each additional piece. They came from across the country in two days (Priority Mail).

 

Enjoy!

 

WSM

[WSM]

The MMO flat sheet anodes are available on eBay (Item number 222043186779) for $15 each. Shipping is $3 for the first one and $1 each for each additional piece. They came from across the country in two days (Priority Mail).

Enjoy!

WSM

After I bought the samples of their electrodes, they must have realized they weren't charging enough for shipping. The current shipping rate is $6 for the first piece and $1 each for additional sheets.

 

WSM

[WSM]

To reuse the depleted perchlorate cell liquor (if it's from a cell which had the residual chlorate destroyed by sodium metabisulfite), consideration should be given to removal of unwanted ions before recharging with chlorides and running it in a chlorate cell.

My first choice has been removal of sulfates with calcium chloride, being careful to remove all calcium salts before use in a chlorate cell. Remove any remaining calcium ions with a very slight excess of sodium sulfate solution and filter out the insoluble calcium sulfate before adding sodium chloride to replenish the chlorate cell electrolyte.

This should work.

WSM

 

The more I study the sodium chlorate process, the more I realize I need to alter my thinking.

 

Through PM discussions with Arthur and research of patents and other published data, I'm beginning to question the wisdom of recycling the spent electrolyte. It seems the need to add much more water is offset by the higher need to replace the depleted sodium chloride as it's converted to chlorate. I need to devise a method to add dry chloride crystals to the electrolyte without letting them mix with chlorate crystals which may drop out as the chlorate concentration reaches saturation.

 

I like a method Swede tried in a bucket cell (I think) for potassium chlorate, where he made a PVC dispersion chamber full of holes which sits in the electrolyte. When the chloride levels drop he can drop dry chloride pellets or crystals into the chamber and the potassium chloride dissolves as it's taken up by the depleted electrolyte.

 

I need to investigate this type of setup for the sodium chlorate experiment I'm working on.

 

WSM

Edited May 17, 2016 by WSM

[WSM]

The more I study the sodium chlorate process, the more I realize I need to alter my thinking.

Through PM discussions with Arthur and research of patents and other published data, I'm beginning to question the wisdom of recycling the spent electrolyte. It seems the need to add much more water is offset by the higher need to replace the depleted sodium chloride as it's converted to chlorate. I need to devise a method to add dry chloride crystals to the electrolyte without letting them mix with chlorate crystals which may drop out as the chlorate concentration reaches saturation.

I like a method Swede tried in a bucket cell (I think) for potassium chlorate, where he made a PVC dispersion chamber full of holes which sits in the electrolyte. When the chloride levels drop he can drop dry chloride pellets or crystals into the chamber and the potassium chloride dissolves as it's taken up by the depleted electrolyte.

I need to investigate this type of setup for the sodium chlorate experiment I'm working on.

WSM

 

It took me only a minute or two to realize It's shown clearly in the first two postings of this thread (Doh!). Swede also mentioned a "fatal flaw" with the plan to try this method.

 

Swede says using a replenishment chamber like this would foul up end of run calculations. I suppose he's right, but I think it just complicates them. If the total mass of the sodium chloride (in my case) consumed is carefully monitored, I think the calculations can be estimated fairly close.

 

Also, my goal is a high concentration sodium chlorate solution (plus low chloride), usable as electrolyte for perchlorate cells. Solid sodium chlorate is another goal, to be dissolved as needed to make perchlorate cell electrolyte and for specialty chlorates. Crystallization is nature's way of purifying substances and if we utilize it properly, our purification processes will improve (as well as be simplified).

 

There is much to do, but I'm getting there.

 

WSM

[WSM]

I think I'd like to make a couple bucket cells later and see how they work for potassium chlorate and also sodium perchlorate.

 

From my experience with perchlorate so far, I think a bucket cell would work very well, and I wouldn't be opposed to running one indoors, since it's not so smelly a system as chlorate cells. Proper venting of hydrogen and ozone is the greatest concern for a perchlorate cell, which is more manageable than the chlorine or hypochlorite fumes from a chlorate cell.

 

I'm considering running it with an LD anode and double, solid plate cathodes, boxed around it. It won't happen soon, but it's definitely a plan for when my sodium chlorate stocks have grown to a high enough level.

 

We'll see...

 

WSM

Edited May 17, 2016 by WSM

[Mumbles]

I was trying to find a solubility graph for mixtures of sodium chlorate and sodium chloride. I was curious as to whether you can "salt out" sodium chlorate by adding sodium chloride. Sodium chloride has very little solubility change over the temperature range we deal with in these cells. I came across a few references of interest, which you may have seen before. It seems like if you know the general composition of your cell liquor, you can add a measured amount of NaCl and collect the crystallized chlorate. By following the solubility curve, you can preferentially isolate the chlorate. You may be able to just continuously add solid sodium chloride to the running cell, along with the standard HCl adjustments and perhaps topping up with water and eventually just start crystallizing out chlorate just like in a potassium cell. Once you have an appreciable amount turning off the cell and allowing it to cool should yield even more.

 

Alternatively, if you're looking for an electrolyte liquor for perchlorate, you may be able to just top up a few times with chloride until you begin to approach saturation to allow for the maximum amount of chlorate percursor. I'm not sure that we'll ever be able to get a low enough chloride content for the electrodes to not be attacked using a pseudo-one pot setup. I know it's more work, but it would seem ideal to isolate the chlorate before moving on to perchlorate. By "salting out" the chlorate from the cell, you may just be able to use the precipitate. I'm far from an expert on this sort of thing, but it sounded like even if all the chloride doesn't initially dissolve that it will be brought back into solution as more chlorate is produced.

 

https://books.google.com/books?id=_R00NqWST6MC&pg=PA167&lpg=PA167&dq=Co-solubility+of+sodium+chloride+and+sodium+chlorate&source=bl&ots=u8X2IiDujU&sig=iAqgR_9MYor9YZ6izPpBQorGsiA&hl=en&sa=X&ved=0ahUKEwj73KWQueHMAhVEez4KHQZ3CzsQ6AEIQDAG#v=onepage&q=Co-solubility%20of%20sodium%20chloride%20and%20sodium%20chlorate&f=false

 

http://www.oocities.org/capecanaveral/campus/5361/chlorate/akagraph.html

[WSM]

I was trying to find a solubility graph for mixtures of sodium chlorate and sodium chloride. I was curious as to whether you can "salt out" sodium chlorate by adding sodium chloride. Sodium chloride has very little solubility change over the temperature range we deal with in these cells. I came across a few references of interest, which you may have seen before. It seems like if you know the general composition of your cell liquor, you can add a measured amount of NaCl and collect the crystallized chlorate. By following the solubility curve, you can preferentially isolate the chlorate. You may be able to just continuously add solid sodium chloride to the running cell, along with the standard HCl adjustments and perhaps topping up with water and eventually just start crystallizing out chlorate just like in a potassium cell. Once you have an appreciable amount turning off the cell and allowing it to cool should yield even more.

Alternatively, if you're looking for an electrolyte liquor for perchlorate, you may be able to just top up a few times with chloride until you begin to approach saturation to allow for the maximum amount of chlorate percursor. I'm not sure that we'll ever be able to get a low enough chloride content for the electrodes to not be attacked using a pseudo-one pot setup. I know it's more work, but it would seem ideal to isolate the chlorate before moving on to perchlorate. By "salting out" the chlorate from the cell, you may just be able to use the precipitate. I'm far from an expert on this sort of thing, but it sounded like even if all the chloride doesn't initially dissolve that it will be brought back into solution as more chlorate is produced.

https://books.google.com/books?id=_R00NqWST6MC&pg=PA167&lpg=PA167&dq=Co-solubility+of+sodium+chloride+and+sodium+chlorate&source=bl&ots=u8X2IiDujU&sig=iAqgR_9MYor9YZ6izPpBQorGsiA&hl=en&sa=X&ved=0ahUKEwj73KWQueHMAhVEez4KHQZ3CzsQ6AEIQDAG#v=onepage&q=Co-solubility%20of%20sodium%20chloride%20and%20sodium%20chlorate&f=false

http://www.oocities.org/capecanaveral/campus/5361/chlorate/akagraph.html

 

Thanks Mumbles. This looks spot on and appropriate to the discussion and my efforts. The referenced attachments are useful, too. I'll study them at length later on (I'm going for medical testing this afternoon, so I can't right now).

 

I'll post more later as I progress my preparations.

 

WSM

 

Edit: I think the use of high concentration sodium chlorate solution would work but the chloride level should be below 10% (and lower is better, but zero percent chloride is best).

Edited May 17, 2016 by WSM

[schroedinger]

WSM did you look into the geocities site for the sodium chlorate? There are a couple of the solubility diagramms and a lot of discussion of how to harvest it fro the cell.

 

He also adresses the fact that a first run will stop at ~600g/l with 100% conversion (which is troublesome because of the anode <100 g NaCl/l problem).

[WSM]

WSM did you look into the geocities site for the sodium chlorate? There are a couple of the solubility diagramms and a lot of discussion of how to harvest it fro the cell.

He also adresses the fact that a first run will stop at ~600g/l with 100% conversion (which is troublesome because of the anode <100 g NaCl/l problem).

 

Yes, thank you. I will try my cell to "get my feet wet" and then modify my approach till I understand the best way to optimize my yield within the limits of my setup. If need be, I can even rebuild it to really ramp things up (I have lots of higher end material stocked and can go to the next level if need be).

 

WSM