The Crop is in...
Entry posted by Swede
262 views
And a fine crop it is. For those unaware, I have been experimenting with chlorate and perchlorate cells for a short time now, on two fronts - the first is the well-known and understood production of both of these salts using an electrochemical cell. Just a few short years ago, the only way to make chlorates and perchlorates (the latter being almost essential in fireworks) was to make your own electrode set, and anyone who has attempted to do so understands the magnitude of the problem. The anode simply... falls apart. A 316 stainless steel anode, normally one of the most chemically resistant steels made, lasts a mere hours before crumbling to dust. Even the cathode, not as harshly treated as the anode, will often be cut in two at the junction between air and electrolyte.
Very effective electrodes are now available for the hobbyist. They are not cheap, but from what I've seen with my limited experience so far, they will last a long time, if not abused. I bought two electrode sets from NorthStar Pyro. One set has a platinum-clad niobium anode for perchlorate production, while the other, which was used with this crop, is a MMO (Mixed Metal Oxide) coated titanium anode. After four days in a hellish environment, 150+ degrees fahrenheit, 15 to 30 amps, and free chlorine everywhere, they look as good as the did fresh from the package. I am impressed.
http://www.5bears.com/perc/ns19.jpg
This is what the bottom of the cell looked like before the harvest. It was hard to tell exactly how much crystalline KClO3 was in there. Crystals sometimes are quite fluffy, and until you physically remove them from the liquor, you just cannot tell.
I set up a filtration rig. The warm liquor is a mixture of dissolved KCl and KClO3, and can be reused to good effect. I've got three liters of electrolyte here, and there is probably 500 to 600 grams of chlorate dissolved in it - No sense in wasting it. In the bottom of the container, I have layered exactly 1,000 grams of KCl salt. I am hoping (probably in vain) that the liquor will dissolve a significant quantity of it, and I can reuse this liquor (after filtration) for the next run.
http://www.5bears.com/perc/chlor01.jpg
The electrolyte in the cell decanted easily, leaving behind only the crystalline mass at the bottom which was hard. A big plastic spoon wouldn't touch this mass. In the end, I took a stainless rod and a hammer, and broke the mass up. Individual large spoonfuls were set into the filter and washed with cold distilled H2O followed by ethanol. I was pleasantly surprised at how thick and heavy the crystals were. The wet crystals weighed 750 grams, and will probably dry to 720 or so. Subsequent yields will probably be better, as the reused liquor will already carry significant quantities of dissolved KClO3; further production at the electrodes will cause the crystals to drop out quickly.
http://www.5bears.com/perc/chlor04.jpg
"How 'bout a nice, fresh, hot bowl of potassium chlorate?! Mmm Mmm good!"
I plan on continuing the runs until I have accumulated a few kilograms. At that point, the perchlorate cell will be tied into the system, and fed with the output of the chlorate cell. Part of the challenge (and the fun) of this sort of chemistry is making pure potassium perchlorate; to this end, I have some reagents coming that will help in my qualitative and quantitative analysis of these salts.
I am proceeding as well on front #2... the production of a viable, amateur-built PbO2 anode, somewhat of a Holy Grail quest among perchlorate enthusiasts. I have some ideas I want to try, most of them involving the production of a composite anode, using predominantly PbO2, but in a matrix of glass fibers and either urethane or epoxy binder.
The real question, why bother with this stuff? Chlorates and perchlorates can be freely bought, and while not particlarly cheap, they are not extremely expensive, either. The process of creation is initially expensive, messy, smelly, a touch dangerous (H2 and Cl2 gasses) and doesn't seem worthwhile.
I can think of two reasons... I believe the day is coming when chlorate and perchlorate sales will become very restricted. Even today, it is becoming a bit of a hassle to purchase these necessary oxidizers. See Firefox for details on what can hapen. If one can make potassium perchlorate, then one has the ability to produce almost any firework known. If I had to choose between perchlorate and potassium nitrate, I'd pick perchlorate. I can make lift and burst with perchlorate, and just about every star known. If limited to KNO3, fireworks will be in a much sadder place, frankly.
The second reason - it's fun! 
3 Comments
Recommended Comments