Sciencemadness Discussion Board - Best Graphite anode recipe (chlorate electrolysis)

Best Graphite anode recipe (chlorate electrolysis)

Bogdonovan - 6-1-2020 at 12:24

Hello everyone, ive given up on trying to make charcoal electrodes and ive gone on and bought some graphite powder. Im looking for a way to make a good electrode but im seeing very different answers to this question, none regarding chlorate electrolysis. I would appreciate if anyone could drop a recipe or a tip for making and using these.

TheMrbunGee - 6-1-2020 at 12:33

Quote: Originally posted by Bogdonovan

Hello everyone, ive given up on trying to make charcoal electrodes and ive gone on and bought some graphite powder. Im looking for a way to make a good electrode but im seeing very different answers to this question, none regarding chlorate electrolysis. I would appreciate if anyone could drop a recipe or a tip for making and using these.

Quick search did not find any non-industrial graphite block forming.

Here is a link on block production, and the process is not for home lab.

I would suggest to order graphite rods or blocks from ebay or something.

And here is an old thread about making graphite.

[Edited on 6-1-2020 by TheMrbunGee]

mhz4.77 - 6-1-2020 at 17:13

If I remember clearly, in Bessemer's autobiography he talked about using pressure to amalgamate graphite powder into rods. Probably took significant tonnage and generated weak rods though. You might get somewhere with a variation on the pencil lead technique: a mixture of graphite and clay, light on the clay, and baked to harden.
Also you _might_ get a mixture of graphite and 'waterproof' (perhaps casein) glue to work, but I would expect it to have poor electrical properties at best.

Twospoons - 6-1-2020 at 19:13

Quote: Originally posted by mhz4.77

Also you _might_ get a mixture of graphite and 'waterproof' (perhaps casein) glue to work, but I would expect it to have poor electrical properties at best.

Conductive inks are essentially graphite + binder so the result may be better than one would expect. For bulk electrodes you'd want a 2 component or a heat set binder - cracking could be a issue with a solvent based binder.
You'd want to use as little binder as possible, preferably one with a very low viscosity.
This also has the possibility on molding the graphite directly around a copper core to create a terminal for electrical connections.

I'd try a slow cure potting epoxy, mixing in as much graphite powder as you can.
Reminder: don't get epoxy on your skin, unless you want an epoxy allergy

[Edited on 7-1-2020 by Twospoons]

markx - 6-1-2020 at 23:50

Quote: Originally posted by Bogdonovan

Trying to form graphite powder into a durable monolithic anode by homeshop techniques is probably not a going to be an easy task.
If I recall correctly the "olden time" industrial process for creating this type of material involved serious sintering durations at very high temperatures reaching into several thousand degrees. Anthracite coal and bitumen mixtures were pressed into blocks of needed size and these were sintered in furnaces for days to convert the mass into graphite. It is not likely that one could cost effectively replicate the process in an amateur setting. If only for satisfying scientific curiosity. Also it is likely that the homemade anode shall have a rather high erosion rate in a chlorate cell.
It makes more sense trying to acquire a monolithic graphite block instead the powder and work from there. Preferably a grade that is designed for electrochemical application. There are different grades of graphite and not all of them tend to be durable in chlorate cell conditions.

Herr Haber - 7-1-2020 at 04:39

Quote: Originally posted by markx

There are different grades of graphite and not all of them tend to be durable in chlorate cell conditions.

I use graphite crucibles in my kiln and totally agree with your statement.

The more expensive crucibles appear shiny and weight a little bit more than the cheap crucibles that look porous even before use.

I'd recommend the OP to get a graphite rod. They are fairly inexpensive.

Fery - 7-1-2020 at 12:10

Visit welding shop and buy slotted electrodes which are graphite rod covered by very thin layer of Cu. Remove Cu e.g. electrolytically.
I've bought this half-full package in a shop where used goods are sold when being bored while waiting for GF spending long time in one of her favorite shop :-D
The price was 20 CZK which is less than 1 EUR / 1 US$
That moment I totally changed my opinion for these kinds of shops.

[Edited on 7-1-2020 by Fery]

Arc Welding Gouging Rods

MadHatter - 8-1-2020 at 11:00

Fery, that's quite a find, especially for the price.
Back in 2007 I used 3/8" diameter(largest I
could find) rods to produce perchlorates with
chlorates as an intermediate step. You can peel
the electroplated copper off with your fingers
and some patience. I used to throw the copper
into my scrap pile. It looks like you have about
half a box. Generally 50 in a box. What's the
diameter of those rods ?

BTW, gouging rods are excellent in chlorate
production. Be aware that the anode will
erode as the temperature rises in the cell.
Also, an intermediate to chlorate is hypochlorite.
Your work area will smell like bleach.

Lookup some of my old posts - search "gouging"

[Edited on 2020/1/8 by MadHatter]

Bogdonovan - 8-1-2020 at 12:19

Hi everyone, and thanks for all the replies. Looking at this thread i think some people got the idea im trying to make graphite? I have the graphite already, just trying to figure out how to make electrodes from it. They dont need to be super durable or anything as this graphite powder is pretty cheap. Ill be trying with epoxy untill i get something that works, then i might try making a lead dioxide coating setup depending on how these will perform. Gouging rods i am acquainted with however they are incredibly hard to find here, no shop has them and i cant find it online. I cant find graphite in any other form than powder here.

Fery - 8-1-2020 at 13:01

Hi MadHatter, thx for supporting the correct translation (so gouging, not slotted)
electrodes are only 7 mm in diameter and yes half a box
when I bought them I was very happy as I had some ideas how to use them and was also very surprised because bought them in unexpected place (I wanted to buy them for 1 decade but did not have time to visit welding shop and then my dream came true unexpectedly without any effort and at a price which was almost free)
for preparation of ClO4- did you cover the graphite with PbO2 ?

Bogdonovan - 8-1-2020 at 13:42

Ok, nevermind this whole thread entirely. Just found a great deal for 50 9,5x305mm gouging rods. It didnt show up on any search engines... Whats the mA/cm² i should be aiming for here? Also, how good will stainless work for a cathode here? I think i have some old spatulas and other junk lying around.