tentacles

It feels kind of useless, but I'll add my two cents:

First, convert your sodium salt to the potassium salt. Now you'll have a product that is easily separated in bulk from the chlorate by recrystallization. First of course, separate the potassium salts from the sodium as best you can in a single step. Now recrystallize the potassium chlorate/perchlorate mixture, and take the product of that operation, dissolve in boiling water until saturated, and at this point would be a good time to use chemical means to destroy any residual chlorate, which will be a small, but detectable, amount. Cool the solution, collect the crystals, etc and somewhere near this point you should have clean perc. The number of recrystallizations may vary, though. Experimentation is NECESSARY. The problem I see with using sodium salts is removing all those pesky sodium ions. That's not easy, and adds a LOT of work.

There's no substantial need for things like pipettes and volumetric flasks - it's far easier to make up a solution that you can compare to, see the link in the next paragraph. Why titrate when you can test against a known level, easily (and cheaply) made up in bulk?

For a good, easy chlorate test you need a reagent called N-Phenylanthranilic Acid - it's mentioned on the wouter pages, and possibly also dann2's pages (the geocities site). If you look here (http://www.apcforum....hp?showentry=20) Swede has refined greatly the usability and sensitivity of this test. His test on commercial perc yielded absolutely no color. Undetectable level of chlorate. He was able to detect 10ppm levels in other tests.

Probably crud from your stainless cathode, they are known to do this. The only "clean" cathode is Titanium, or another valve metal (excepting aluminum). Seems like such a shame to use a good platinum anode to make chlorate, though.

What are you using to test for chlorate? Sodium chlorate is *very* hydroscopic, I doubt you can get it dry enough to do a brute force test like dragging hammer through sulfur. If you want to see if your anode is working, try electrolyzing potassium chloride, you should get visible results MUCH faster. As Bonny said, buy a bag of KCl as sodium free water softener salt. I paid $9 for 20kg at 'Rona'. Converting NaCLOx to KClOx is time consuming, and troublesome at best. You're better off starting with KCl from the get-go unless you're operating on an industrial scale. You can dissolve enough KClO3 in warm (40C) water to make big, Na free yields out of a good sized cell.

Are you using any kind of cell additive?

reply to old posting -
pkhow - there are some people working on a MMO perchlorate anode, we have some leads that *may* be viable. There are viable chlorate anodes, certainly, and rather simple to make.

marble: I found a method somewhere that involved melting KNO3 and slowly adding your lead to the melted salt. This formed PbO, somewhat more practially than merely heating lead.

As the Pb ion plates out of the tank, the nitrate ion will be left and forms HNO3 - you really don't want a very low PH in your plating solution. The "high nitric" plating baths are primarily to prevent Pb from plating out at the cathode - which you can prevent by using a copper cathode, or using copper nitrate (plates Cu at the cathode, essentially makes your cathode copper). The idea was to redissolve any Pb as it plated out. What you're going to want is some PbO, PbCO3 or PbOH to add new Pb ion to your plating tank. PbO is suggested, since you can just dump a bunch in and let it dissolve as the plating progresses. Litharge (PbO) is sold for mining/assaying purposes and also at a few ceramics shops - many stores like to be "lead free" which is bad for us, maybe good for potters. There are several ways to produce it, and none of them really appeal to me at the moment.

Marble, try and get some PbO as well, you can dump it in your PbO2 plating tank to control PH and provide more lead ion to plate out. Try ceramics shops and mining/assay suppliers.



Things I've noticed regarding perchlorate manufacture, various stuff here..

If you're using copper cathodes, don't bother with Cu(NO3)2 - the copper anodes supply the same function without the hassle.

The lowest current density I've seen in a patent for PbO2 is 100ma/cm^2 - their efficiency rate was similar to the other tests in the patent. It was a patent for using NaF in a chloride to perchlorate cell. (in other words, there may not be a minimum current density to generate perchlorate)

It is possible that plating PbO2 at a lower current gives a smoother plating - I have no reference for this, only my own minimal experience.

Also, for those who haven't seen it, there was a reference on science madness to a substitute for sufactants in PbO2 plating:
"Ceramic particles are preferably incorporated in the electrolyte solution because these particles, when suspended in the electrolyte as by constant agitation, prevent oxygen bubbles from clinging to the substrate anode during the electrolysis and consequently eliminate the formation of holes in the lead dioxide deposit. Typical ceramic particles are minus 325 mesh ceramic beads and, when employed, are used in a typical concentration range of 1 to 10 grams per liter. "

I plan on trying some "silica flint" from my local pottery shop; it's listed as 325 mesh SiO2.

The shop I've ordered some nitric acid from (40L of 30%) sells greenhouse and lawn care supplies; I may see if they have some surfactant and try a combo of surfactant and silica.