Sciencemadness Discussion Board - Graphite Substrate Lead Dioxide anode

Graphite Substrate Lead Dioxide anode

ecos - 5-11-2015 at 07:57

Hi All,

I found the cost of Pt anode for perchlorate cells so high and I am searching for other solutions. I like to share my findings since it might help others.

I think lead dioxide anodes are very good solutions but their cost on internet is still high.

I found three methods to make lead dioxide anode:
1- Burn lead with propane torch to have lead dioxide : https://www.youtube.com/watch?v=eXgzEXjdoWw
I am not sure if this would work or not !
3- electroplating Titanium substrate with lead dioxide on it.
2- electroplating graphite substrate with lead dioxide using electrolysis : https://www.youtube.com/watch?v=D7bpoXKak-4

The second method is called Graphite Substrate Lead Dioxide anode "GSLD". It is discussed in details in the attached PDF. The setup looks like this :

The second video above has implemented the same setup and achieved a very nice anode.

some pictures for professional setup and anodes for motivation :

I think this process doesn't cost much compared to buying the anode from amazon or ebay. I also like the idea of controlling the thickness of the PbO2 layer. I found anodes on internet with 1 millimeters PbO2 layer but it was over $60.

I wonder if I can use magnetic stirrer to circulate the electrolyte instead of rotating the anode. This would make the setup even more simpler.
whats your idea?

More references :
http://www.apcforum.net/forums/blog/swede/index.php?showentr...
http://www.oocities.org/capecanaveral/campus/5361/chlorate/l...

Attachment: HowToMakeSodiumPerchlorate.pdf (211kB)
This file has been downloaded 3705 times

Detonationology - 5-11-2015 at 08:41

The idea of having the electrode attached to stirrer it quite innovative; however, I can see it being a real pain to maintain. Especially with chlorates and perchlorates, corrosion can be a big problem. It would only take a few days for the motor in the overhead stirrer to burn or short out.

Quote: Originally posted by ecos

1- Burn lead with propane torch to have lead dioxide. I am not sure if this would work or not!

I think this would be very optimistic for this to work effectively unless the Pb is atomized or combusted with an oxidizer.

ecos - 5-11-2015 at 10:35

Quote: Originally posted by Detonationology

The idea of having the electrode attached to stirrer it quite innovative; however, I can see it being a real pain to maintain. Especially with chlorates and perchlorates, corrosion can be a big problem. It would only take a few days for the motor in the overhead stirrer to burn or short out.

Quote: Originally posted by ecos

1- Burn lead with propane torch to have lead dioxide. I am not sure if this would work or not!

I think this would be very optimistic for this to work effectively unless the Pb is atomized or combusted with an oxidizer.

This process is for plating the graphite anode with PbO2. This process takes hours.
I am not alking about spinning the anode in chlorate cell

.

Fan motor will not burn if you left it run for days

Detonationology - 5-11-2015 at 11:22

Quote: Originally posted by ecos

Quote: Originally posted by Detonationology

Quote: Originally posted by ecos

1- Burn lead with propane torch to have lead dioxide. I am not sure if this would work or not!

I think this would be very optimistic for this to work effectively unless the Pb is atomized or combusted with an oxidizer.

This process is for plating the graphite anode with PbO2. This process takes hours.
I am not alking about spinning the anode in chlorate cell

.

Fan motor will not burn if you left it run for days

Your info is lucid, I just confused myself with another thread I had open. Sorry for my prior input. Wouldn't copper also precipitate onto the graphite rod?

[Edited on 11-5-2015 by Detonationology]

hissingnoise - 5-11-2015 at 11:58

Quote: Originally posted by Detonationology

The idea of having the electrode attached to stirrer it quite innovative..

It's a fairly well tried and trusted technique to minimise pinholing caused by stubborn bubbles adhering to the anode . . .

phlogiston - 5-11-2015 at 12:11

I drew that crappy picture of your setup in the 90's of the previous century. Never expected to see it show up again 15+ years later! Most of the rest of that pdf is from other sources though.

Copper does plates out, but on the cathode, not on the anode. In fact, the very function of the copper is to prevent lead from being plated out. The copper preferentially plates out and forms a thin, well-adherent layer on the cathode. If you don't add the copper, a spungy voluminous mess of lead will plate out on the cathode. This contaminates the cell and causes short circuits.

The original paper I got the method from also included a method to replenish the copper and lead in the plating electrolyte by circulating it through a system where it first passes through a tank with a mixture of PbO and CuCO3, then through a pH adjustment stage and then back in the cell. I'll see if I can find a dig up a copy of the paper and post it.

It is not really necessary though if you have enough plating solution and are not plating a very thick layer. The concentration of lead will only drop very little.

The anodes I got were more shiny than the one in that video. I recall they looked like they were made from obsidian.

[Edited on 5-11-2015 by phlogiston]

Detonationology - 5-11-2015 at 12:26

"The most important use of lead dioxide is as the cathode of lead acid batteries."
Is the cathode actually plated with lead oxide, or is it a product formed by the reaction of the battery?

ecos - 5-11-2015 at 15:18

Quote: Originally posted by phlogiston

I drew that crappy picture of your setup in the 90's of the previous century. Never expected to see it show up again 15+ years later! Most of the rest of that pdf is from other sources though.

Copper does plates out, but on the cathode, not on the anode. In fact, the very function of the copper is to prevent lead from being plated out. The copper preferentially plates out and forms a thin, well-adherent layer on the cathode. If you don't add the copper, a spungy voluminous mess of lead will plate out on the cathode. This contaminates the cell and causes short circuits.

The original paper I got the method from also included a method to replenish the copper and lead in the plating electrolyte by circulating it through a system where it first passes through a tank with a mixture of PbO and CuCO3, then through a pH adjustment stage and then back in the cell. I'll see if I can find a dig up a copy of the paper and post it.

It is not really necessary though if you have enough plating solution and are not plating a very thick layer. The concentration of lead will only drop very little.

The anodes I got were more shiny than the one in that video. I recall they looked like they were made from obsidian.

[Edited on 5-11-2015 by phlogiston]

It is very interesting to know that you draw that picture

.
I think this topic is very important due to the high cost of lead or platinum anode

An 10cm x 10cm anode covered with 1mm PbO2 costs $103 : Link

I was amazed when I know about GSLD. I can get carbon rods from batteries and electroplate them. It would be cheaper and I can make thicker layer. It was very nice to find a video for the whole process.

Didn't you think to circulate the electrolyte using magnetic stirrer ? this would make the setup more simpler.
I think this would avoid the forming of bubbles as well. I am not sure.

I am looking forward for your answer and pictures

[Edited on 5-11-2015 by ecos]

Aurium - 5-11-2015 at 16:02

This is great. I wish I had known about GSLD earlier!
This makes a homemade electrochemical cell so much more viable.

I wonder if the electrode will resist concentrated sulfuric acid?

Also, how many amps are you putting through a percolate cell?
Instead of hours at 2A maybe one can get the chemistry done in minutes using some 100Amps.

hyfalcon - 5-11-2015 at 17:00

I highly recommend reading a couple of the stickies at the top of the Techno-chemistry section. This thread is what brought me to SM.

https://www.sciencemadness.org/whisper/viewthread.php?tid=50...

I just wish all the links in it still pointed to something.

[Edited on 6-11-2015 by hyfalcon]

hyfalcon - 6-11-2015 at 05:48

Quote: Originally posted by Aurium

This is great. I wish I had known about GSLD earlier!
This makes a homemade electrochemical cell so much more viable.

I wonder if the electrode will resist concentrated sulfuric acid?

Also, how many amps are you putting through a percolate cell?
Instead of hours at 2A maybe one can get the chemistry done in minutes using some 100Amps.

Depending on quantity, you put 100 amps through your electrolyte and it will boil. You don't want more than 200-400mA per square centimeter dependent upon electrode material. Any more than that causes undue erosion of your anode.

ecos - 24-12-2015 at 02:11

I am thinking to make PbO2 anode using lead dioxide spongy in battery.
I will collect it and then melt it to form a solid electrode then use it for electrolysis.

Even if i have Pb within my PbO2 this won't harm since it would be oxidized from air while melting.

I think this process is toxic. but it should give me high thickness PbO2 electrode.

would this work ? I think it is basic idea

[Edited on 24-12-2015 by ecos]

phlogiston - 24-12-2015 at 06:39

No. PbO<sub>2</sub> decomposes when heated

careysub - 24-12-2015 at 08:06

Quote: Originally posted by Detonationology

"The most important use of lead dioxide is as the cathode of lead acid batteries."
Is the cathode actually plated with lead oxide, or is it a product formed by the reaction of the battery?

The first commercial lead-acid battery, by Gaston Planté, consisted of two sheets of pure lead immersed in the acid electrolyte.

The breakthrough that made lead-acid batteries practical for widespread use was Camille Faure's development of the lead dioxide paste electrode. This consisted of a lead grid lattice, into which a lead oxide paste was pressed, forming a plate.

Here is a page discussing paste electrode manufacture today:
https://www.osha.gov/SLTC/etools/battery_manufacturing/plate...

So the answer is both can be used, but the paste method makes superior batteries.

ecos - 24-12-2015 at 08:41

Then we have PbO2 paste inside car battery.
The key point now is to transfer this paste to a rigid electrode !
phlogiston state that , PbO2 will decompose while heating !
do I need to make electroplating or there is a better technique ?

PHILOU Zrealone - 24-12-2015 at 11:00

Quote: Originally posted by ecos

Then we have PbO2 paste inside car battery.
The key point now is to transfer this paste to a rigid electrode !
phlogiston state that , PbO2 will decompose while heating !
do I need to make electroplating or there is a better technique ?

You could also make a porous clay pot (gardening flower pot) to hold the paste and inserted inside the Pb or metallic net rolled in cylinder...

ecos - 24-12-2015 at 15:55

do you mean something like that :

comment from the website :

Quote:

with anodes lasting from hours to months. Pieces of Lead Dioxide were put into a porous plastic bag/wrap. A Graphite rod was placed on top of the contents of the bag/wrap and the contents + part of the Graphite rod was plated. The bag/wrap used in the picture was mesh material used in the garden to keep down weeds.

as you can read, it will not last for long time and not reliable.

PHILOU Zrealone - 31-12-2015 at 09:34

Quote: Originally posted by ecos

do you mean something like that :

comment from the website :

Quote:

as you can read, it will not last for long time and not reliable.

No not like that...a bag will not last long vs a backed clay gardening pot...
I was thinking to something like this:

ecos - 31-12-2015 at 17:00

I think your idea is based on the very tiny holes in the pot will not allow the PbO2 to be consumed in solution , am i right?

I think the problem here will be the current will be very small due to the small surface area of PbO2. do you agree?

PHILOU Zrealone - 31-12-2015 at 17:24

That is indeed a bit the idea...unsoluble PbO2 paste will remain inside the pot while ions will flow through the porous clay.

The surface will be the inner surface of the clay pot...thus more than your PbO2 plated electrode.
True that the diffusion of the ions through clay may be slightly more limiting than free diffusion in open media...

ecos - 1-1-2016 at 06:15

Ok , It make sense now.

for the lead grid/wire , can it be substituted with metals like SS , Al, Cu ?

PHILOU Zrealone - 1-1-2016 at 06:57

Quote: Originally posted by ecos

Ok , It make sense now.

for the lead grid/wire , can it be substituted with metals like SS , Al, Cu ?

The lead grid I had in mind would be rolled in cylinder, the diagram I posted is a kind of open cut of the system.

The idea is that the PbO2 paste is in contact with Pb so you get the couple PbO2/Pb in the case some side reaction occurs.

The paste will hold intimate with the grid and if it peals off, it simply remains where it is because it can't fall away --> remains in place...this will circumvent by a simple mechanical way the pealing off effect of Pb/PbO2 electrodes...

In principle this system will remain serviceable for long...as long as the PbO2 remains in the pot --> depends on how log the clay pot will resist electrochemical cell run conditions and how long it will remain integer vs hot saline solution. Some glazed clay do form micro cracks in saline/acidic/basic media...here the pot has to be glazedless...because glazed pot will be much less porous to ions...

The use of Al especially (or Cu) is forbidden in the conductive saline media...they would sacrificially corrode first.
Cu may eventually be used out of the mix (inside the Pb wire and over in the air)

Stainless Steel, if it is what you mean by SS, may be tested, but usually it doesn't like chloride, hypochlorite in acidic or basic media...so maybe just like the Copper --> out of the mix (inside the Pb wire and over in the air) but this may be costly vs Copper pipe and electrical wire...

phlogiston - 6-1-2016 at 18:04

Quote: Originally posted by ecos

I am looking forward for your answer and pictures

I found one of my first anodes made with this method. The coating was a bit thin, but it looks quite shiny and free of pinholes. Never tested this particular one in an actual cell, but later ones held up quite nicely and produced sufficient perchlorate for my needs (which were quite modest, just enough for a few small-scale pyrotechnics experiments).

ecos - 8-1-2016 at 01:53

@Phlogiston, Very interesting ! what is the dimension of this anode?

I wish I can make one.

I would like to know the current density you used for your anode.

phlogiston - 8-1-2016 at 03:46

The graphite substrate is 8mm diameter and 60mm long.

The current density for plating the PbO2 onto the anode or the current density in the perchlorate cell?

ecos - 8-1-2016 at 06:20

I was asking about the percolate cell but it is also interesting to know about the plating current density as well.

would it be a problem to have high current density for plating ? I see the PDF uses 5v supply.

NaClO4

Laboratory of Liptakov - 7-2-2016 at 09:37

I dont know, what it help us, but here is pretty a new video with clay cup membrane for producing NaClO4.
https://www.youtube.com/watch?v=8ZnYqmbiukI

ecos - 7-2-2016 at 12:40

Thx Liptakov,

Quote:

There are two advantages to this method, you can use graphite as an anode, and you can get 100% conversion due to no cathodic reduction.

I think the video explains the idea of PHILOU Zrealone that he expressed in his thread.

I need a little help now to understand this statement "you can get 100% conversion due to no cathodic reduction" what does this mean ?

[Edited on 7-2-2016 by ecos]

Laboratory of Liptakov - 8-2-2016 at 01:35

Well, I understand, this: Get 100% change from NaClO3 on NaClO4. It is very important for produce NH4ClO4. Without group ClO3. Or 0,1% ClO3 + 99,9 ClO4. Cathodic reduction (for this type galvanic reaction) is question for PHILOU and others kings of chemistry. LL.

markx - 8-2-2016 at 06:00

It is quite hard, not to say impossible, to obtain pure perchlorate crops by direct electrochemical means and without any further purification. The resulting cell liquor, even though it mostly contains perchlorate, will still be contaminated by a small amount of residual chlorate. This can be removed by chemical means though:

http://www.oocities.org/capecanaveral/campus/5361/chlorate/d...

Another means is to purify the perchlorate is by heating to convert the residual chlorate impurities into perchlorate and chloride. The chemical means probably is more reliable though...

As a matter of fact the thermal conversion of chlorate into perchlorate is actually quite appealing. Considering the simplicity of the conversion process and the ease with which chlorate can be produced in bulk by the electrochemical method, then it may make sense to omit the hassle of platinum or GSLD and the electrosynthesis route for perchlorate altogether.
Just produce coupious amounts of chlorate by electrolysis of chloride with MMO anodes and heat it to conversion temperature in a porcelain or stainless crucible (preferably with PID temp control). For sure the method is less effective in terms of yield, but way cheaper and quite simple:

http://people.ku.edu/~matt915/projects/chloratedecomp.html

https://www.youtube.com/watch?v=EC4OPnvPkLU

The percursor chlorate must be free of organic or metallic contaminants that may cause a firey explosion or decomposition into chloride and oxygen via catalytic action...

Hennig Brand - 8-2-2016 at 12:30

Good post! I have done the research a few times as well, but never got around to trying the thermal decomposition method. It does seem to have a lot of advantages over the electrochemical approach. Yield is a bit low, but so what. It is a relatively quick process, with minimal capital investment in equipment and like you said the chlorate feed is so cheap and easy to make in large quantities.

ecos - 9-2-2016 at 07:51

Quote: Originally posted by Hennig Brand

Good post! I have done the research a few times as well, but never got around to trying the thermal decomposition method. It does seem to have a lot of advantages over the electrochemical approach. Yield is a bit low, but so what. It is a relatively quick process, with minimal capital investment in equipment and like you said the chlorate feed is so cheap and easy to make in large quantities.

Thermal method is well known but it is risky. chlorate became very active when heated and any organic existence might end with explosion !
try to avoid it.

ecos - 9-2-2016 at 10:06

Lead Dioxide Electrodeposition Under Ultrasonication : https://www.youtube.com/watch?v=UgYgcymCJ20

Hennig Brand - 9-2-2016 at 13:37

Quote: Originally posted by ecos

Quote: Originally posted by Hennig Brand

Thermal method is well known but it is risky. chlorate became very active when heated and any organic existence might end with explosion !
try to avoid it.

I am not saying this to be rude, but driving a car can be extremely dangerous too if one doesn't have the necessary skills. Like driving, I am sure that I could learn to perform this process safely as well.

Laboratory of Liptakov - 10-2-2016 at 03:36

To control dangerous processes, that's great art, that's great beauty. Just as God.
Dr. Liptakov

ecos - 17-2-2016 at 09:17

I am thinking to electroplate graphite rod with lead dioxide.
I found two different kinds of graphite electrodes, one is black and one is gray.

what is the difference between both ?

hissingnoise - 17-2-2016 at 09:42

The grey rods contain graphite and the black one looks like compressed carbon . . . ?

Mabus - 17-2-2016 at 13:22

Vitreous carbon maybe?

ecos - 19-2-2016 at 05:10

i think the difference between carbon and graphite electrodes is the crystal structure of the carbon atom.

would electroplating of compressed carbon rod work for chlorate cells ?

ecos - 25-2-2016 at 09:39

I am ready to build this setup :

I bought lead , some copper and diluted nitric acid 65%.
I have a fan motor and some beakers.
I think I am ready.

I have a problem now to connect the shaft of the motor with a aluminium rod and to connect the Al rod with the graphite rod.

is there a better way than using glue? I prefer mechanical ways. I wish I find something like a drill chuck that can connect things together with different dimensions.

any suggestions ?

Hennig Brand - 25-2-2016 at 11:09

This has worked for me in the past for reasonably low torque arrangements:

Plastic tubing (vinyl, polyethylene), from the hardware store comes in all the standard sizes. The outside diameter of one size is the inside diameter of another. Short lengths of tubing can be used as couplings. If connecting two shafts of different diameters, build up the small shaft with smaller diameter couplings. If the shafts are standard sizes the tubing will fit snuggly like a glove. If friction isn't enough then drill a hole through all (shaft and coupling) and put a pin through, or use an adhesive of some sort.

ecos - 25-2-2016 at 13:29

Thanks a lot hennig ,

you mean a tube like this ?? :

I got your idea, this will be between the shaft of the motor and the Al tube.
what about the connection between Al tube and graphite rod?

my problem , I plan to get graphite rods with different diameters (13 mm , 19mm , 23 mm , ..)

Hennig Brand - 26-2-2016 at 11:57

You're welcome. There are at least several different types of tubing available at the better hardware stores around here. Even the more basic stores usually have vinyl and polyethylene. Also, a tube with the least curvature is best (outside start of a large diameter roll perhaps). With the two shafts close together in the "coupling" the connection is almost perfectly straight even with tubing with a bit of bend (imbalance of stress from one side of the tube to the other causing curvature). I think this would work with a graphite shaft as well.

The plastic tubing (coupling) also acts as a torsion shock absorber. Depending on the tubing chosen the coupling can be very elastic. This could possibly be a good thing when brittle shafts are involved.

[Edited on 27-2-2016 by Hennig Brand]

Laboratory of Liptakov - 27-2-2016 at 03:39

Crisis place in the red circle. If the connection is soft, graphite misalignment occurs. You need hard tube against axis displacement.

hyfalcon - 27-2-2016 at 05:34

How about something like this:

https://www.zoro.com/climax-metal-products-coupling-rigid-st...

Hennig Brand - 27-2-2016 at 06:04

If it is so soft and so much slack is allowed that it is flopping around when spinning that is a problem of course. However, even relatively stiff polyethylene, which holds its shape well under most normal conditions, has enough elasticity (is non rigid) so that spikes in torsion force are greatly reduced (lowered in amplitude and stretched out). Too soft is of course a problem. Not sure it is even needed, it was just a passing thought.

ecos - 8-3-2016 at 02:52

"I think if someone has lead dioxide powder he can add some epoxy and make stiff anode". I read it somewhere but I don't remember the source.

I found a nice clean technique to make lead oxide : https://www.youtube.com/watch?v=Wzm3N0xPyGU

I think if we add lead to a ball mill and run it for long time. the lead will be atomized and oxidized as well. (I think this is the reason why we add 5% carbon while milling Al to cover it and avoid oxidation)

if this will work we could have lead oxide or dioxide and make anodes easily. I am still investigating this point.

Laboratory of Liptakov - 15-7-2016 at 06:00

As very good idea is clay cap from Philou aparatus. From page 1 this thread. I have questions. Is possible as active surface ( in clay cap garden) use different lead oxides? Thus only pure Pb3O4 - minium? Has the Minium similarly properties (for galvanic process) as PbO2 ? Or worked Pb3O4 only with mix in PbO2? 1:1 ? Is posible used Pb3O4 without clay cap aparatus? Will be worked high pressed rod from Pb3O4 ? Thanks,....LL.... :cool:

ecos - 20-7-2016 at 06:14

I have a question.
I found some offers on the internet for crucible graphite. some of them are used and with good price.

anybody know if they can work as electrodes?

Jstuyfzand - 20-7-2016 at 06:47

Quote: Originally posted by ecos

I have a question.
I found some offers on the internet for crucible graphite. some of them are used and with good price.

anybody know if they can work as electrodes?

Problably, although they might have some additives to make them more suitable for their purpose, I guess.

markx - 20-7-2016 at 22:48

Quote: Originally posted by ecos

I have a question.
I found some offers on the internet for crucible graphite. some of them are used and with good price.

anybody know if they can work as electrodes?

They will definately work as inert electrodes, but when we are talking about anodes for Cl- conversion to ClO3- then the wear rate may be not too good. And yes, there might be some unwanted additives in the crucible composition, but one can not be sure about that.
Graphite anodes inevitably crumble and wear down in this application, especially under higher current densities and temperatures. If I remember correctly from older russian literature, then the critical point for graphite erosion in chlorate production was at 40C. Any higher than that will cause increased wear on the anodes. But then again in amateur application this aspect may not be that important. If you can get the material cheap then a bit of erosion will not be a problem. What may be a problem is getting the carbon residue out of the cell liquor during purification. It requires meticulous filtering to clear up the solution and when potassium chloride is used, the filtering must be done while solution is hot. It can be accomplished, but presents a rather uncomfortable stage in the process. And from the point of safety and stability it is not a good idea to leave carbon residue in your final product.

ecos - 21-7-2016 at 00:28

Thx all for the help.
I am planning to electroplate it with PbO2.

ecos - 21-7-2016 at 13:13

here is my carbon rod

length = 26 cm,
Diameter = 4 cm.
Weight = 630 g

it costs = $2.5

its time to electroplate it

markx - 24-7-2016 at 22:45

Just make sure to avoid any contact with the lead nitrate solution.....one can receive a lifetime worth of damage in a single afternoon with this compound. Also watch out for any airborne spray or mist that may be generated during electroplating.

PbO2 anode

Laboratory of Liptakov - 2-8-2016 at 08:18

On youtube is video about prepare PbO2 anode from pure Pb (carrier substrate) only with use H2SO4, current 30 A / 5V. Very small second Copper electrode. So simply ? Only H2SO4 30% ? I mean, that is a nonsense. (time 5:58)
https://www.youtube.com/watch?v=kylurawZEWs
...LL... :cool:

PHILOU Zrealone - 2-8-2016 at 08:30

Quote: Originally posted by Laboratory of Liptakov

On youtube is video about prepare PbO2 anode from pure Pb (carrier substrate) only with use H2SO4, current 30 A / 5V. Very small second Copper electrode. So simply ? Only H2SO4 30% ? I mean, that is a nonsense. (time 5:58)
https://www.youtube.com/watch?v=kylurawZEWs
...LL... :cool:

Yes that simple!
It is what happens into a car battery when recharging.

ecos - 2-8-2016 at 08:55

Quote: Originally posted by Laboratory of Liptakov

I read about this procedure before.
it was stated that the coated PbO2 with this process is very bad and fall easily from the anode !

Laboratory of Liptakov - 2-8-2016 at 10:17

Thanks ecos....:-) I do not understand speaking words from video. I estimate, that in easy prepare the anode will some problem. Maybe do it some a better process for coating from PbO2. For example rotating rod shape electrode /substrate/ and use cloth for entrainment bubble gas. And polishing of planar surface during rotation coating PbO2. Simply help tense of cloth. ..LL.. :cool:

ecos - 2-8-2016 at 15:37

I found the reference.

wiki : https://en.wikipedia.org/wiki/Lead_dioxide

Quote:

Electrolysis
An alternative synthesis method is electrochemical: lead dioxide forms on pure lead, in dilute sulfuric acid, when polarized anodically at electrode potential about +1.5 V at room temperature. This procedure is used for large-scale industrial production of PbO2 anodes. Lead and copper electrodes are immersed in sulfuric acid flowing at a rate of 5–10 L/min. The electrodeposition is carried out galvanostatically, by applying a current of about 100 A/m2 for about 30 minutes. The drawback of the lead electrode is its softness, especially compared to the hard and brittle PbO2 which has a Mohs hardness of 5.5.[11] This mismatch in mechanical properties results in peeling of the coating. Therefore, an alternative method is to use harder substrates, such as titanium, niobium, tantalum or graphite and deposit PbO2 on them from lead(II) nitrate in static or flowing sulfuric acid. The substrate is usually sand-blasted before the deposition to remove surface oxide and contamination and to increase the surface roughness and adhesion of the coating.[12]

PbO2 anode

Laboratory of Liptakov - 3-8-2016 at 03:46

Very important. Especially, that main problem is in different hardness between carrier and PbO2. Thanks..LL... :cool:

ecos - 4-8-2016 at 23:39

I attempt to connect my carbon rod to the shaft of a motor but i failed

the carbon rod diameter is 4 cm and the shaft of the motor's diameter is 1 cm !

I tried to use glue or silicon to attach it, but when i run the fan motor for some time, they split !

rod

Laboratory of Liptakov - 5-8-2016 at 02:53

You can drilled to carbon precise center hole, diameter 10,3 - 10,6 mm. Estimate depth 3 cm. And on small different (10,0mm steel carrier) use paper tape. Was try I am, hold it a good. Condition is long of steel rod from motor 35 mm. Connect and disconnect is possible. Recomend the slit between carbon and steel (for paper tape, not plast) is 0,1 - 0,3 mm. ..LL... :cool:

ecos - 20-9-2016 at 07:19

I am afraid to drill into the rod. it might get cracked

I was thinking of a solution to avoid the air bubbles that stick to the electrode while plating and affects the quality.
what if i put the electrolysis cell in a reduced pressure room ! won't that get rid of the air bubbles?
if yes, there will be no need to use a motor to rotate the rod so fast !

[Edited on 20-9-2016 by ecos]

yobbo II - 20-9-2016 at 13:34

Goog luck with the graphite subsrate. As the page, where the pictures at the top of this thread came from states, all the anodes fell apart.

The original Japanese spinning graphite article here.

http://www.sciencemadness.org/talk/files.php?pid=143479&...

and attached as well

Get some mmo and coat that.

In the extract from Wiki above I quote

"Therefore, an alternative method is to use harder substrates, such as titanium, niobium, tantalum or graphite and deposit PbO2 on them from lead(II) nitrate in static or flowing sulfuric acid. "

If you add sulphuric acid to lead nitrate you will get an immediate ppt of lead sulphate. The line is wrong.

Yob

Attachment: Bulletin of CS Japan.pdf (748kB)
This file has been downloaded 631 times

[Edited on 20-9-2016 by yobbo II]

ecos - 20-9-2016 at 23:15

Quote:

If you add sulphuric acid to lead nitrate you will get an immediate ppt of lead sulphate. The line is wrong.

I think you are right, it shall be lead nitrate and copper nitrate not sulfuric acid. This is also found in the first posts in this thread !

I will read the document you sent and provide my comments later.

markx - 21-9-2016 at 01:30

Oxidizing lead metal surface under anodic potential in sulfuric acid solution does not tend to form a durable layer of PbO2. The layer is thin and will not work in chloride solution for long. All in all it does not seem to be a practical solution....more a visualisation of the effect. Atleast in my experiments I could not get something that would resemble an inert anode by function.

The only somewhat working way still seems to be the electrodeposition of PbO2 from lead nitrate/copper nitrate solution. But also this method is quite complicated to use for the practical electrodeposition of thick PbO2 layers. Properties of the plating bath have to be corrected/stabilised during lenghty deposition process. Suitable additves or operating regimes established to avoid pitting, cavitation, dendrites and internal fracture stresses. Not an easy task to be honest....also one can expect to contaminate the premises that the experiment is conducted on and oneself with lead nitrate quite severely. There will spills and spray during the process that accumulate on surroundings, so there is a real danger of lead poisoning.
So perhaps if the goal is not to study the PbO2 electrodeposition process in depth, but more the electrosynthesis of perchlorates then it would make more sense to spare up for a platinum anode. They do run expensive, but trust me, a functional lead dioxide anode shall not come for a cheap price either.

The alpha way?

yobbo II - 21-9-2016 at 07:33

The toxicity of the lead nitrate is what makes the whole process nasty. If lead nitrate (and lead in general) was harmless it would make a great fun process.
I have seen mmo and tin oxide coated titanium coated with first a thin layer of alpha lead dioxide, then the thicker beta coat. Where the beta falls off in places after some use of the anode (in chlorate or perk cell) the alpha layer can stay on for an amazing length of time (sometimes). Someone once suggested that perhaps the way to go would be just coat with thin layers of alpha lead dioxide. This has been shown to work. You need a lead plumbate bath. Lead oxide (litharge) + sodium hydroxide and plate slowly at low current density. You do not need large amounts of lead compounds. Litharge is easy to get. The bath is still toxic of course.
Not much toxic spray from bath (not many bubbles). No ph control. Not much reduction in concentration of lead compound in bath as the actual volume of Pb doixide being plated is small in total.
It will make chlorate /perchlorate. The beta is preferred. A reason that beta is preferred is that the voltage accross cells (chlorate or perk) is lower that with alpha which is very advantageous in industry but irrelevant with the home maker.

Alpha paper attached.

Yob

Attachment: AlphaLD.zip (229kB)
This file has been downloaded 547 times

ecos - 28-3-2017 at 01:08

do any body know PbO2 anode provider on internet ?
I want to order one. Unfortunately most of the internet sources i know are gone !

anodes

Laboratory of Liptakov - 28-3-2017 at 10:10

Early coming times, when will stop sale for all perchlorate anodes. Stay only graphite rods for welding (and chlorates).
For luck, is here method heated conversion Na/K ClO3 on Na/K ClO4. Yield is about 60% on insert xClO3, but still is it better than nothing..... :cool:

...LL

RogueRose - 28-3-2017 at 11:26

Quote: Originally posted by Laboratory of Liptakov

Early coming times, when will stop sale for all perchlorate anodes. Stay only graphite rods for welding (and chlorates).
For luck, is here method heated conversion Na/K ClO3 on Na/K ClO4. Yield is about 60% on insert xClO3, but still is it better than nothing..... :cool:

...LL

Could you please make this intelligible in some way?

Laboratory of Liptakov - 28-3-2017 at 13:33

Here is method on conversion KClO3 on KClO4 https://www.youtube.com/watch?v=EC4OPnvPkLU

Bert - 17-12-2017 at 11:26

Have any tried a copper coated Carbon arc light electrode for the substrate when plating a Lead dioxide anode for perchlorates? I have a few, 3/8" Dia. x 9" long as I recall

markx - 27-12-2017 at 06:11

Quote: Originally posted by Bert

Have any tried a copper coated Carbon arc light electrode for the substrate when plating a Lead dioxide anode for perchlorates? I have a few, 3/8" Dia. x 9" long as I recall

I see no reason why it should not work once the copper coating has been removed either chemically or electrochemically.

On another note regarding the lead dioxide anode....I've been contemplating a novel approach for generating the required bath constituents in situ electrochemically from rather benign raw materials. The idea was to use a common cell with a solution of ammonium nitrate into which several sets of electrodes are immersed, driven by separate power supplies (or separate h-bridge style mosfet switches at least) to first electrochemically generate lead nitrate and copper nitrate by dissolution of sacrificial anodes made from the respective metals and then electodeposit the lead dioxide from these previously generated bath contituents on a separate set of electrodes....
The power supplies would be driven one at a time for predetermined intervals to minimise side reactions/cross polarisation and to allow for the more or less complete conversion of the generated bath constituents with every cycle. The cycles could be quite short in fact, perhaps on the scale of milliseconds. A sort of multi power supply pulse plating setup if you will....
Granted the ammonium nitrate cell would have to be probably separated by a suitable membrane to avoid the alkaline cathodic compartment products from migrating into the anodic compartment and precipitating the lead and copper nitrates before there is a chance to use them in the lead dioxide forming reaction. Surely this approach is techically complicated and presents some serious electronical challenges, but I like the idea of not having to mess around with coupious amounts of lead nitrate and the fact that one probably will not have to build up a serious concentration of it in the bath at any given point in time with this approach.
I did test this concept in a very simplified form several years ago: took a solution of ammmonium nitrate and drove current through it for a short period of time (5 seconds range) by using a lead metal anode, thus propagating lead (II) ions into the solution, then replacing the sacrificial lead anode with a stainless steel substrate.
And the damndest thing happened: a nice shiny black layer of lead dioxide deposited on the substrate. Of course my cell did not have a membrane, so most of the lead that got into solution quickly precipitated in contact with the cathodic products, but the concept worked for a short period of time. In fact I also tested the thus obtained lead dioxide layer as anode in sodium chloride solution and was pleasantly surprised by the notable evolution of free chlorine (organoleptically detected). Of course the plating was not perfect, so the stainless substrate quickly started to dissolve in the chloride solution under anodic potential, but as a proof of concept that was quite encouraging.
I never got into more involved research regarding this concept, but perhaps the time is here...

Laboratory of Liptakov - 27-12-2017 at 09:37

Maybe is time, because almost identical method I did also. However my attempt was ending as an smoke bomb with Pb steams. Melted AN + dissolved PbNO3/2 , during cell - current run, did increased temperature. After some second was started autoreaction between all materials together. Was used dry sand for stopped this madness. But I believe, that this is maybe way... :cool:

Simoski - 28-12-2017 at 00:13

Guys I have lead nitrate and copper nitrate and have wanted to electrodeposit Pb02 over MMO Ti mesh for a while now, what current density must I use for the alpha and what current density for the beta? What other additives do I need? Does the pH rise during plating and I need to acidify the electrolyte ?

Simoski - 28-12-2017 at 09:24

Does the beta crystal structure resemble obsidian?

Simoski - 28-12-2017 at 09:27

Has anyone attempted to electro-deposit PbO2 at elevated and reduced pressure? If not, reply if you have any ideas on how to build a machine that can. Let's build the most inert anode ever!

[Edited on 28-12-2017 by Simoski]

ecos - 16-1-2018 at 04:12

i tried a lot and failed. it is not easy to electro-deposit PbO2 on anything !

complicated setup and nasty chemicals.

spend some money and by an anode !

Laboratory of Liptakov - 9-2-2018 at 11:09

Ecos has right. Buy anode is much more easily. And here it seems, that is possible go to from NaCl on NaClO4 in one step. Even without adding any next inhibitors etc. https://www.youtube.com/watch?v=VQb4jLp-Vuc with PbO2 anode of course.

NeonPulse - 1-4-2018 at 05:10

Ok. Had a success on making one of the anodes. Basically used the setup described in the first post on this thread and with help from the video listed in that post. I used a 100mm by 8mm diameter graphite rod as the substrate and firstly sanded it shiny smooth with 1200 grit sandpaper. Next it was thoroughly wiped down with acetone and given a pre treatment electrolysis in NaOH a 10% solution with a stainless steel cathode for about 30 mins. After this it was submerged in a 5% HNO3 solution for another 15-20mins and washed with water. Next the graphite was left to dry overnight.
For plating the substrate I made a solution of 400mls using 50g of Lead nitrate and 10g of copper nitrate, this was acidified to PH of 1 with diluted HNO3. The rod was attached to a small 12v motor with a speed control PWM device added. This was done by sliding a brass couple onto the motor shaft and slipping a bit of hose over it in which the graphite rod was inserted. Some copper foil was wrapped around the hose with a glob of silver conductive glue to make contact with the rod to allow a sliding contact to the power supply. There was a bit of copper wire as the cathode. The substrate was immersed and the motor started along with the power supply which was set to around 6v and 2a and was kept playing fro just over 1 hour. The results were pretty good. The coating looks sturdy and does not rub off easily. There’s no pitting anywhere with a few dendritic growths on the base. The added weight to the anode totals 10.6g. A couple more of these and we should be good to go for a perchlorate cell. I do have a couple of salvaged MMO anodes from a pool chlorination setup I would love to attempt to plate. Possibly under ultrasonic vibrations to move the bubbles away. I got them cheap so they are expendable.

077F901E-0534-45A7-B573-B41D52EB78AC.jpeg - 1.7MB

A1548E47-BFC4-4395-835C-0D83DA8AC500.jpeg - 1.4MB

markx - 1-4-2018 at 08:55

This looks very sturdy, Neonpulse! Would love to hear how they hold up in perchlorate cell conditions. My thin coatings were surprisingly fragile in terms of durability and tended to flake off.

XeonTheMGPony - 2-4-2018 at 04:25

use a pumped bath, all the motor does is stir the solution, using a cheap systolic pump or other type you move the solution rather then electrode.

for screen you can cut a section of pipe that make the required flow geometry to wash off any bubble adjust flow volume to ensure effective bubble removal but not so fast to disturb plating

NeonPulse - 17-4-2018 at 23:22

Ok a bit of an update. I recently made 4 GSLDA’s for my perchlorate project and they looked solid, like they would work. Well looks are secondary to performance..... three of the anodes failed. I firstly put three together on a Ti connection and it was going well for a few hours after running the cell for a little I was dismayed to see a pile of Lead dioxide at the bottom of the cell. Shortly after the liquor began to take on an obvious brown colour of graphite destruction. Doh. The next day after filtering the liquid I tried again with two more anodes - one failed in less than 15 mins and this is not surprising as it was the one that looked the worst and I called a fail. Luckily the last one is actually holding up. It was one of the 3 from the first anode I tried. It has been going for hours with no problems and it is forming perchlorate. The cell is running at 5v 14a and it’s plodding along fine. There is very little erosion as I can see tiny amount of brown particles after stopping the cell for the night but it is working. I tested some of the cell liquid ice cold with methylene blue and it turn the desired purple with purple precipitation.

214054AA-B4CB-4C68-853E-2A49EA69A046.jpeg - 1.6MB

70A6210C-D76E-4475-BD6E-C45A1B692F68.jpeg - 1.2MB

Laboratory of Liptakov - 18-4-2018 at 02:18

Very important information for anyone. This shows, that anode is not some easy manufacture. Never. However x ClO4 is great result.
You info are key info on the field an heavy xxClO4 production. Hat down... :cool:

yobbo II - 18-4-2018 at 16:18

It's dead easy to make graphite substrate lead dioxide anodes. It is real hard to make one that will last for any appreciable length of time.
As the professionals stated a long time ago.
At least three mm thick coating (better to have five).
Perfect coating with no holes either of the visible kind or the invisible kind.

This requires a proper set up and a large quantity of chemicals in relation to the total amount of lead dioxide that you are going to deposit.

and some luck IMO!

Most end up with lots of work and an anode that lasted half (or less) of a batch of perk.

Yob

symboom - 19-4-2018 at 12:14

Problems with lead dioxide from flaking off

https://www.google.com/amp/www.instructables.com/id/Make-Con...

Would this work it conductive glue it uses charcoal powder

markx - 20-4-2018 at 04:25

Quote: Originally posted by symboom

Problems with lead dioxide from flaking off

https://www.google.com/amp/www.instructables.com/id/Make-Con...

Would this work it conductive glue it uses charcoal powder

I think this glue approach will hardly work under perchlorate synthesis conditions. Such conductive coatings can be used as the initial layer in plating operations when using nonconductive substrates as the cathode (plating on plastic details e.g.) I used a silver based conductive paint when I was working on thick platings to grow moulds for forming plastic details with intricate geometry. Basically the plastic detail was coated with conductive paint and then a thick coating of Cu or Ni plated over that to create an exact replica for forming further details made out of plastic. That was way back during the years of my bachelor studies in material science department.

Seemingly the only way to a more or less durable anode is to create a homogenous and thick coating of PbO2, as already mentioned before (but that is no trivial task and reproducibility seems poor).