While awaiting massive PVC sheets and such for an industrial-styled cell, I decided to try a budget electrode I had found for perchlorate production using some of the KClO₃ that I had so far produced.

I must say, I am sick of chicken-shit setups like the one you are about to see. Food bins, blobby silicone, poor electrical contact, messy, haphazard in a way. But by doing this, I learn a few things, such as heat generation, byproducts, venting, temperature, current, and voltage control. Most importantly, I can learn how this budget electrode (more on that later) will do.

The basic setup is a Click-Clack 4.3 liter food storage container. The body appears to be some sort of polycarbonate, while the lid feels like HDPE. I'm not expecting this container to last more than two or three runs, mainly due to the rubber seal. In the picture above, the closest electrode is the anode. It is a Pt over Ti anode used mostly for electroplating, and was much cheaper than most typical Pt anodes for hobby perchlorate production. I am saving my Northstar Pt/Nb anode for more serious efforts. The larger electrode to the rear is a homemade Ti cathode that costed all of $5, with shipping being the largest part of the deal. It came from ebay in two pieces - the thin shank, and the thicker body. I practiced welding Ti with some tiny scrap pieces, and found with good cleanliness and a piece of pure Ti wire as filler rod, I could do some reasonable TIG welds... thus, the shank was secured to the body with a pair of welds like this:

The volume of the cell is ~ 4 liters. Anticipating that the cell would run at 40 degrees C, I determined the amount of potassium chlorate needed for a saturated solution of 4 liters at 40 degrees; the quantity needed was 600 grams:

I found it was infinitely easier to get 600 grams of chlorate dissolved in the water if I first brought the water to near boiling. At a higher temperature, it dissolves almost immediately, yet if the solution began to cool, it would not begin to produce crystals until it was below 40 degrees. This gave me plenty of time to set the cell up, get the current flowing, so as to maintain a bit of heat.

The heavy cables here are more important that one might think. As the cables from the power supply get smaller, precious volts are wasted in just moving current through the leads, and the leads themselves heat up, again wasting energy. These are #4 copper welding cables crimped to copper connectors, and nuts and bolts are used to attach the cables to the electrodes. #4 copper will probably be fine up to 60 or 70 amps. Above that, I'd move to #2. Good quality jumper cables can be scavenged for the copper, but be sure they are, in fact, heavy enough. Get rid of the alligator clamps and go to a mechanical connection like this:

My $25 eBay power supply was an amazing kill, but it does have a drawback... it will do 80 amps, but only 10 volts, so I must be especially aware of things like electrode spacing, and the previously mentioned cable size. For my industrial "super-cell", I'm considering a multi-electrode sandwich, with two Pt electrodes sandwiched with three Ti cathodes, spaced VERY closely using a PTFE bracket with milled slots, and wired at the top, above the lid, with a Cu bus bar. The spacing on this cell is probably 0.750" or 19mm, and for the next-gen cell, I'll probably need to go to 6mm or less.

It's bubbling away right now... we'll see what happens. The extremely low solubility of perchlorate should cause a very quick appearance of crystals, and starting with reasonably pure chlorate should help create a clean product. I lost probably 3 grams of chlorate in the preparation of the electrolyte, so I'm calling this batch 597 grams to start, with a theoretical yield of 674.9 grams of perchlorate. Of course it won't be close to that, as significant chlorate will remain behind in the electrolyte. Driving a cell to near zero chlorate is not practical, as it would require huge voltages and probable destruction of the anode.

One of the conclusions to draw from this run is when do I halt electrolysis of a perchlorate cell, and how do I identify that point? Another important process is the ultimate purification of the KClO₄ so that it may be legitimately labeled "Pyro-ready Potassium Perchlorate."

Stay tuned!