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Newsgroups: rec.pyrotechnics
From: (Arno Hahma)
Subject: Re: electrolysis of KCl03 .
Date: Tue, 11 Jul 1995 17:43:05 GMT

In article <3tsekv$>,
 <> wrote:

>     Where is info on electrolysis available (net, literature references).
>I would like to make chlorate, or better yet, perchlorate from cheap starting

Chlorates are so cheap it does not pay to make them yourself with the
exception of sodium free barium chlorate. However, perchlorates are
considerably more expensive, so they are worth making. Sodium chlorate
is best as the starting material - someone has already done most of the
electrolyzing for you.

A major problem with chloride -> chlorate electrolysis is the erosion
of the electrodes. In the industry, they solve it by two ways: replace
the electrodes frequently or use platinum clad titanium as the
electrode material. It doesn't erode (well, it does, but slowly enough
to allow long maintenance cycles).

For the perchlorate electrolysis, there are little choices for the
electrode material: platinum group metals and lead dioxide. I have a
cell that uses the latter, for obvious reasons ;). Unfortunately, lead
dioxide cannot be used for chloride -> chlorate electrolysis, since it
erodes too fast.  It works just fine, but you get erosion rates of
about 10..20 grams/kilogram of chlorate produced. I consider that
unacceptable as long as I don't have a convenient means of producing
new anodes.

On the other hand, chlorate -> perchlorate causes no erosion to the
anode, there is no lead detectable from the cell solution, unless you
had it in the water before loading the cell.

>materials like sodium chloride or lithium hypochlorite. This would be for 

Lithium? Well, if you are going to make a lithium perchlorate rocket,
tell me too how you got it to work ;).

>I would like to focus on the methodology and make a simple, easily duplicated
>technique so that anyone who was interested could easily do it. 

A perchlorate cell is not going to be an easy task to build.  The
hardware as such is not complicated, but the electrical and electrode
problems are. Corrosion is also a major problem, it is hard to keep the
electrical connections from dissolving.


From: (Gerald L. Hurst)
Newsgroups: rec.pyrotechnics
Subject: Re: sodium chlorate
Date: 12 Jan 1996 21:04:13 GMT

In article <4d4ebo$>, (Power
Incarnate) says:

>I found a relatively large quantity of sodium chlorate that I didn't now 
>I had, and I'd like to know if it's good for anything. The FAQ didn't 
>mention it, so I'm assuming it's not. What I'd really like to know is a 
>safe way to get rid of it. (Can it be thrown out normally, flushed, or do 
>I have to treat it as hazardous waste?)

Sodium chlorate in aqueous solution is widely used as
a weed killer. It is usually sold in combination with
a larger quantity of sodium metaborate to limit its
use as an oxidizer in explosive formulations.

Jerry (Ico)

Newsgroups: rec.pyrotechnics
From: wfvisser <>
Subject: Re: home-making KClO3
Date: Tue, 13 Feb 1996 23:13:56 GMT

Klaas van Ditzhuyzen wrote:

> In an old German textbook on chemistry (which is still very good)
> W.Ostwald: Grundlinien der anorganischen Chemie, Steinkopff Dresden 1919(!)
> I read about preparation of KClO3 by electrolysis:
> Electrolyze a solution of potassium chloride which yields
> hydrogen gas and OH- ions at the cathode and chlorine gas at the anode.
> To get the KOH solution and the chlorine, the anode and cathode areas
> should NOT be mixed, otherwise the Cl2 reacts with the OH- which yields
> ClO3- ions.
> Howerer, according to the book, to obtain chlorate, DO mix the solution.
> The reaction is according to Ostwald:
> Cl2 + 6OH- -> 2ClO3- + 3H2
> If one already has potassium hydroxide, one can just prepare the chlorine
> by mixing an acid with hypochlorite toilet cleaner (CAUTION: OUTDOOR ONLY
> because Cl2 is HEAVILY TOXIC !!) and catch the Cl2 to lead into the KOH
> solution.
> Does somebody have experience with making KClO3 ?
> Klaas

I do have experience in making KClO3 and KClO4 by electrolysis, and
have found a lot of literature of the subject. I am also corresponding
with other people that have experience making KClO3 and KClO4. If you
have any questions, e-mail me.

My procedure is not very efficient, but I am working on a new improved design. 
Here's (in short. Ask if you don't get it) how I do it:

I use a saturated KCl solution, although a mixture of KCl with some
NaCl may be better due to better conductivity of the electrolyte. I
also add 2g of potassium dichromate (carcinogenic! Maybe an alternative
would be better) per liter of KCl solution. This reduces carbon
erosion, electrolytic reducion of hypochlorite (an intermediate in the
formation of chlorates) and helps control the pH. I use carbon rods,
and a 4A power supply. I try to control the pH by adding small amounts
(several ml's) of concentrated HCl. The solution should be slightly
acidic (pH ~ 5.5). I keep the temperature down with a fan. It should be
30...40C. Higher temp increases efficiency (70C...80C optimum), but
also increases carbon rod erosion. The cells consist of 1.5l
coke-bottles. I cut out the bottom, and put the carbons through the
hole on the other side. I seal with molten stearic acid (candles) to
protect the connection between the carbons rods and the wires to the
power supplie.  I continue electrolysis for 100Ah per 200ml of
electrolyte. My current density is too high (should be
0.01A/cm2...0.03A/cm2), but I usually run 2 cells in series, two in

If you have questions, e-mail me,

wouter visser (

Newsgroups: rec.pyrotechnics
From: wfvisser <>
Subject: Re: home-making KClO3
Date: Fri, 16 Feb 1996 14:50:49 GMT

<> wrote:

>Apparently if you let the apparatus run for an extended length of time,
>the chlorate will be further reduced to the _perchlorate_ ion (ClO4-).
>I'd think this would be more desirable as it is less sensitive than
>potassium chlorate. Adding KCrO4 or K2Cr2O7 will increase the amount of
>product you get.

and at the same time the dichromate or chromate will protect your carbon 
rods from erosion (to some extent). Note that potassium dichromate is a 
suspected carcinogenic, and toxic. It is very inefficient to make 
perchlorates with carbon anodes. They will deteriorate very quickly, even 
when treated with wax or linseed oil. All metals (including iridium and 
titanium, as mentioned in an earlier post) except 
iridium-and-osmium-free-platinum will wear out quickly.

Newsgroups: rec.pyrotechnics
From: wfvisser <>
Subject: Re: home-making KClO3
Date: Mon, 19 Feb 1996 22:02:41 GMT

William wrote:
>      I try to control the pH by adding small amounts
>      (several ml's) of concentrated HCl.
> Doesn't the HCl destroy chlorates (another intermediate)?
> Although perhaps it helps with the KCl->KClO phase...

It helps with the ClO- --> ClO3- phase. The ClO- ion does not react. If 
acid is present (near the anode, or when HCl is added), HClO is formed. 
This reacts to give ClO3-.


Newsgroups: rec.pyrotechnics
From: wfvisser <>
Subject: Re: Electrodes and home-making KClO4
Date: Mon, 19 Feb 1996 22:50:16 GMT

TWilk wrote:

> (Dan Major) wrote:
> >What about using "plain" titanium for the reaction vessel and electrodes?
> >I've got some out-of-spec aircraft parts that I could use if this will
> >work.
> I think its well worth a try... 'tho you would only need to use the titanium
> for the anodes. The vessel can be plastic of glass and the cathode just a bit
> of bent coffee tin.
> My cell is roughly...
>            /anode
>           /    /cathode
>          /    /
>     |  (/)   |       (/)= connection of wire to titanium anode
>     |  (X)   |            covered in epoxy
>     |  |X|   |
>     |  |X|   |       |x|= 3/8" dia plat.titanuim mesh folded
>     |  |X|   |            into a tube about 6" long
>     |  |X|   |
>     |  |X|   |
>     |  |X|   | <------ cathode is steel from a coffee tin
>     |  |X|   |         (cleaned with acetone to remove the
>     |  |X|   |          plastic coating) rolled into a tube
>     |  |X|   |          about 8" long and 1 1/4" dia
>     |  |X|   |
>     |  |X|   |
>     |        |
> ...the whole thing is submerged in electrolyte at about 45degrees
> and runs at around 3-4A at 35 degrees C  (approx)
> This is very successful, but has only been used for small trial batches
> while I've been monitoring A/V/Temp etc.
> I'm just working on a constant-current supply before I setup a multi-
> electrode bath for a bit more volume production. My guess is that
> if I supply const. current (limited within 3-6.5v), the temp. should
> be easier to control for a start and the process will gradually move from
> 3v up to 6v operation as the products form.
>         ..
>        .  .\|/
>       .   - * -
>       .    /|\
>       .
>       .
>       .
>     TonyW   []

This is interesting. I did quite extensive literature research on the
subject, and thought that titanium was unsuitable since it absorbed
hydrogen. I never used it since I expected it to erode quickly.
(iridium and osmium free) Platinum coated titanium was mentioned often
as a good anode though. Has someone ever tried Leaddioxide anodes
(Maybe graphite/PbO2) for chlorates? and for perchlorates? What
conditions (ie temp, pH, electrolyte, current density)? How does it
perform? How does your Ti-anode cell perform? (Have you measured
yields? What electrolyte composition?). Sorry to ask so many questions.
I am trying to find the optimal design.


Newsgroups: rec.pyrotechnics
From: wfvisser <>
Subject: Re: home-making KClO3
Date: Tue, 20 Feb 1996 17:55:44 GMT

Wes Brzozowski wrote:

> |>
> |> and at the same time the dichromate or chromate will protect your carbon
> |> rods from erosion (to some extent). Note that potassium dichromate is a
> |> suspected carcinogenic, and toxic. It is very inefficient to make
> |> perchlorates with carbon anodes. They will deteriorate very quickly, even
> |> when treated with wax or linseed oil. All metals (including iridium and
> |> titanium, as mentioned in an earlier post) except
> |> iridium-and-osmium-free-platinum will wear out quickly.
> What about silicon? The technical grade lumps available from chemical
> supply houses have sufficient impurities that they're quite conductive.
> They're not porous, so the deterioration common to carbon rods shouldn't
> happen. Will they be deteriorated by the chlorine or the NaOH that form
> as intermediates? I'm not interested in actually trying to make a material
> that can be purchased so cheaply, but the problem is an interesting one.
> I'd posted a query to this effect some months back, but got no nibbles.
> Anyone in the current discussion up to giving it a try or at least sharing
> their thoughts?
> Wes B.

Silicon reacts with NaOH solution to give silicates. I don't think the 
reaction is very speedy though with the low concentrations of OH- in the 
electrolyte. It would indeed be interesting to try. I only can get 
silicon powder. Is there a good way to form this into electrodes? Anybody 
else likes to try this?


Newsgroups: rec.pyrotechnics
From: wfvisser <>
Subject: Re: Making KClO4 - anode questions.
Date: Wed, 28 Feb 1996 22:54:15 GMT

/E00680/cstevens/Carl Stevens wrote:
> In the documents I am reading KClO4 is produced with carbon anodes and
> steel cathodes. The document says that this will produce "significant
> amounts of chlorate as a by product." Another document states that
> commpercial producers of KClO4 use lead dioxide or platinum for anodes.
> My questions are:
>      If one were to attempt KClO4 production would it be
>      worth the effort to try and find either a lead dioxide or a platinum
>      anode?

Yes. Carbon rods erode quickly for perchlorate synthesis. I've been
corresponding with somebody who has an efficient procedure for coating
the carbons with linseed oil. After treatment they perform much better,
but both platinum and PbO2 anodes are superior when making perchlorates
from chlorates. for the chloride-->chlorate step, carbon andodes can be

Lead dioxide anodes can be made at home. I am doing literature research
on the subject, and if you like, I can keep you informed. I don't know
how PbO2 anodes behave in chloride-->chlorate conversion though. For
chlorate-->perchlorate however, they have many advantages: last long at
high temps and low Cl- conc. (expect several months per anode) and they
are cheap. I will start experimenting with these anodes as soon as
possible (availability of spare time is limiting factor). The
disadvantage is that lead compounds are toxic. Preperation of the
anodes requires a soluble lead salt (soluble lead salts are usually
more toxic than unsoluble lead salts) such as lead nitrate or lead
acetate. If appropriate steps are taken however, the procedure can be
done at home safely.

Platinum anodes last almost forever. They can withstand high current
density, high temperatures and low chloride concentrations. They are
suitable for both chloride-->chlorate and for chlorate-->perchlorate.
Best would be platinum coated titanium anodes.

>      Should one attempt to harvest the chlorate after decanting the
>      liquid from the perchlorate crystals?

In the recrystallisation, perchlorate precipitates first. When chlorate
crystals start to appear, I usually decant the liquid, and wash the
perchlorate with ice-cold water. I store the chlorate solution. I have
only recantly begun producing perchlorate. I concentrated on chlorate
before. The chlorate solution can be added to the electrolyte, and it
will be converted to perchlorate. When I have optimalised my process, I
will use the chlorate solution I stored so far.

>      The product is said to be "essentially free" of chlorate after
>      double crystalizing and washing several times with cold water.
>      If one were to use the finished product for stars and gerbs
>      should it be treated as if it contained chlorate?  (Avoiding
>      compositions containing sulfur, etc.?)

I'm sure the product contains some chlorate. If I were you, I'd treat
it as if it was pure chlorate as long as you've not done a test. It
should be possible to remove most chlorate (say less than 0.1% left) by
recrystallisation in a few steps, but I don't know how many steps will
be neccessary.

> For reference I am using the two chlorate documents on TIP's page. Pointers
> to other references would be appreciated.

Far as I know, there are no other similar documents on the net. If you
have access to a good library though, you could start by searching
Chemical abstracts for "chloric acid, potassium salt" or the sodium
salt and for the salts of perchloric acid. I do have links to books
too. Interested? --> mail me.

From: (Dan Major)
Newsgroups: rec.pyrotechnics
Subject: Re: Making KClO4 - anode questions.
Date: 28 Feb 1996 20:55:59 GMT

I've been testing both the silicon wafers and the Ti plate. Both
seem to work well. I had constructed a small cell using two 50mm
wafers held in place in a small plastic container. The Si wafers
conducted very well, and I was getting good current flow
through the cell until one of the alligator clips holding one of
the wafers got into the electrolyte solution. It ate through the
clip rapidly, contaminating the solution and ruining the clip.
No erosion was noticed on either wafer. A similar experiment was
conducted using a Ti plate/ Si disk electrode setup, and with a
Ti plate / steel sheet electrode. I was only able to run these
cells for a short time, and noticed no erosion from the Ti.

My news server has died so it may be a while before I can post
back to this group.

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