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PbO2 anode? Make It at home.


kingkama

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Well in the last months i decided to make a new PbO2 anode.

Materials

1 Ru/Ir well used near death anode

1.5 liters of PbNO3 full saturated bath 

1/7 of the Total PbNO3 weigth in CuNO3

Some stripe of lead metal long as the anode 

1 cathode or preferred 2 in Ti 

A Power source where you can regolate voltage and amperes.

Some HNO3 acid

Lots of patience.

 

Procedure

Prepare the bath in a suitable container for the electrodes, if possible a glass beaker with magnetic stirring, not necessary but useful.

Also insert the lead strips into the bath that do not touch the two electrodes

Run the power source at the highest possible amperage for 5 minutes then switch to 0.5 amp for 12 hours. After 12 hours add a few ml of nitric acid and replace the lead strips if they are spent . Continue in this way until you obtain the desired thickness, at least 3 mm per side.

The amperage switching can be carried out several times during the plating hours in order to create alternating layers of alpha and beta lead (beta is the best for oxidizing and is formed at low amperage)

The presence of copper nitrate is essential since copper dissolves metallic lead so when the bath changes color you need to empty the container and recover the copper that has precipitated.

The copper should be dissolved in nitric acid and the solution added to the bath.

In this way the lead in solution remains at an optimal level and there is no acid dispersion.

Arm yourself with a lot of patience and time, because the plating takes a few days and must necessarily be thick.

Edited by kingkama
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10mm welding carbon rood are easy way reproducible and cheap. And if the coating comes off later, the solution will not be contaminated by other metals that dissolve. Cylindrical shape, so it can be easily spinned with a motor. It is good to spin it with a motor so that the coating is smooth, and remove the bubbles. Without it, pinholes are formed and the coating will not be smooth. If pinholes are formed, the coating disintegrates. The solution should be kept 60°C hot. There will be less wear in a NaClO3 or NaClO4 cell with a near neutral pH. But unfortunately, it will wear out slowly. At 2 volts around I got a pretty strong coating. I did it with several interruptions. The slower it is made, the stronger the coating. It should be coated as slowly as possible, or the coating peels off quickly in a perchlorate cell. I read somewhere that a pro coating made about 36 hours. First the graphite are boiled in Na3PO4, and used NaOH  as anode, so that the coating adheres properly later.

Edited by mx5kevin
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Try this parameters:

Lead Nitrate PbNO3 375g/l

Copper Nitrate CuNO3 14g/l

TritonX 100 0.5g/l

Nitric acid 5g/l

pH controlled with nitric acid: pH 1.5-6.0

Solution temperature 70-90°C

Anode current density: 10 to 100 mA /cm2 1.46V is required for the formation of the dioxide layer

Current maximum 2.2V 0.4A

The electrode must be rotated rapidly in the solution with a motor.

Basic graphite 10mm welding rood.

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Use a graphite electrode, even using surfactants the result is always disappointing and not very long-lasting, using an mmo electrode it gives the possibility of having a functioning and very long-lasting electrode, which even if not perfectly covered does not pollute the cell and is not destroyed, therefore it can be re-plated at the end.

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5 hours ago, kingkama said:

Use a graphite electrode, even using surfactants the result is always disappointing and not very long-lasting, using an mmo electrode it gives the possibility of having a functioning and very long-lasting electrode, which even if not perfectly covered does not pollute the cell and is not destroyed, therefore it can be re-plated at the end.

I agree  PbO2 plated Ti MMO anode are the best. There is a problem if something else is used instead of titanium, say stainless steel. When the lead dioxide layer comes off, the solution starts to dissolving the metal. The problem is that it is difficult to do this at home in such a way that the coating is almost as durable as the factory one. Preparing such an anode at home is at least as costly as making perchlorate itself. A usable anode that won't wear off the lead dioxide too quickly requires to make some anodes before. The problem with homemade anodes is that they fall apart after a few uses. Wear is much faster than with factory anodes. One of the the biggest problem by far is the resulting bubbles that stick to each other on the electrode when plating. One of the cheapest things that I think can help if the electrode cannot be rotated is a vibrating motor. But the problem what I see is those who have more serious lab equipment they all say that homemade PbO2 anodes fall apart quickly. Few people write accurate statistics who have already made several such electrodes at home, using the exact method and how long they last.

Example in a perchlorate cell the exact anode how many hours did it last? How much NaClO4 did it manage to produce with it in total.

https://odysee.com/@mx5kevin:a/tuzijatekutmutatok:c

Search this document: Deposition of Lead Dioxide (PbO2) on various substrates, with refinements. By Swede. A lot of good old useful content has disappeared from the internet.

To be honest, I experimented with it for a while, but I thought it was too costly and lead is toxic. Then I buyght a costumer specific platinum anode corresponding to the production of a 6-8mm thick 10cm long graphite electrode for a small cell. The factory made lead dioxide anode in a Ti base wears out slowly too. It crashes after several runs. But I think it's much more worth buying it. If someone wants to buy, buy MMO, PbO2, Pt, Ti electrodes directly from the manufacturer. Ebay is full of fakes, shoddy products. I also saw someone selling lead dioxide anodes made in his own garage for making perchlorate on Ebay. Don't buy these.

Edited by mx5kevin
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4 hours ago, mx5kevin said:

I agree  PbO2 plated Ti MMO anode are the best. There is a problem if something else is used instead of titanium, say stainless steel. When the lead dioxide layer comes off, the solution starts to dissolving the metal. The problem is that it is difficult to do this at home in such a way that the coating is almost as durable as the factory one. Preparing such an anode at home is at least as costly as making perchlorate itself. A usable anode that won't wear off the lead dioxide too quickly requires to make some anodes before. The problem with homemade anodes is that they fall apart after a few uses. Wear is much faster than with factory anodes. One of the the biggest problem by far is the resulting bubbles that stick to each other on the electrode when plating. One of the cheapest things that I think can help if the electrode cannot be rotated is a vibrating motor. But the problem what I see is those who have more serious lab equipment they all say that homemade PbO2 anodes fall apart quickly. Few people write accurate statistics who have already made several such electrodes at home, using the exact method and how long they last.

Example in a perchlorate cell the exact anode how many hours did it last? How much NaClO4 did it manage to produce with it in total.

https://odysee.com/@mx5kevin:a/tuzijatekutmutatok:c

Search this document: Deposition of Lead Dioxide (PbO2) on various substrates, with refinements. By Swede. A lot of good old useful content has disappeared from the internet.

To be honest, I experimented with it for a while, but I thought it was too costly and lead is toxic. Then I buyght a costumer specific platinum anode corresponding to the production of a 6-8mm thick 10cm long graphite electrode for a small cell. The factory made lead dioxide anode in a Ti base wears out slowly too. It crashes after several runs. But I think it's much more worth buying it. If someone wants to buy, buy MMO, PbO2, Pt, Ti electrodes directly from the manufacturer. Ebay is full of fakes, shoddy products. I also saw someone selling lead dioxide anodes made in his own garage for making perchlorate on Ebay. Don't buy these.

I agree with you on the terrible quality of some products on various online markets, in my experiment I used an MMO anode (titanium covered with iridium ruthenium oxides) which had been used for a lot of time and due to errors in use it had worn out, before throwing it away I decided to try covering it in PbO2.I've had good luck using the knowledge I gained from reading a lot of material online. Lead is toxic but by using a pair of gloves and minimizing environmental dispersion there are risks Relatively low. I have tried many times with graphite but with terrible results, I agree that buying a platinum anode is an interesting solution at first glance but what to do if you have the availability of one MMO anode at the end of its working life and you don't want to just replace it or throw it away, this way I got an anode that is virtually indestructible unless you drop it on the ground.

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  • 1 month later...

I found sellers on Taobao/Aliexpress/etc. selling lead dioxide anodes. Is it really necessary to make them?

I know last time I tried it they fell apart, but I was running it with a computer power supply at 5 volts, without any means to adjust voltage at all. I think they need a constant current supply, and I think I can use a cheap stick welder for this, because stick welders are a constant current supply, and are designed to short circuit.

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I had success (9 years ago) using a power supply with constant voltage (CV) and current (CC) capability. By adjusting the power supply to maximum voltage and ramping the current up slowly from zero, it ran in CC mode and the Current density I chose was 0.1 A/cm2 of Anode area, and the voltage was stable at about 4.2 Vdc during the run of about 70 hours for a 3 liter cell.

This was using a commercial lead dioxide on titanium mesh anode (from China) surrounded by two solid titanium cathode plates. Everything ran reasonably well and produced NaClO4 solution which, after destroying residual chlorate with SO2, made chlorate-free sodium perchlorate solution (useful for making potassium perchlorate by metathesis with potassium chloride solution, which I did).

WSM B)

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My question is, has anyone tried using a stick welder as a constant current supply?

I did some titanium welding today... not the best but it works. I found very high weld current, enough to quickly melt the metal and fuse it is necessary. The middle was where I tried to attach it, but it wasn't a good fusion (full of impurities because I couldn't keep the gas flowing before the titanium cooled). Once I understood that very high current is needed I was able to fuse it better. Both rod and plate is grade 2 titanium.

If I get a MMO anode or whatever that isn't already welded, I can easily do that.

As far as I know, TIG and stick welder is constant current, meaning the voltage adjusts itself to get the desired current. MIG welder is constant voltage it seems.

The edge roughness is me attempting to cut the Ti plate with a plasma cutter. Angle grinder cutting discs had extremely hard time cutting titanium, but plasma just cuts it like it's not even there. It throws white hot sparks everywhere though.

PXL_20240414_171702581.jpg

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22 hours ago, taiwanluthiers said:

My question is, has anyone tried using a stick welder as a constant current supply?

I did some titanium welding today... not the best but it works. I found very high weld current, enough to quickly melt the metal and fuse it is necessary. The middle was where I tried to attach it, but it wasn't a good fusion (full of impurities because I couldn't keep the gas flowing before the titanium cooled). Once I understood that very high current is needed I was able to fuse it better. Both rod and plate is grade 2 titanium.

If I get a MMO anode or whatever that isn't already welded, I can easily do that.

As far as I know, TIG and stick welder is constant current, meaning the voltage adjusts itself to get the desired current. MIG welder is constant voltage it seems.

The edge roughness is me attempting to cut the Ti plate with a plasma cutter. Angle grinder cutting discs had extremely hard time cutting titanium, but plasma just cuts it like it's not even there. It throws white hot sparks everywhere though.

PXL_20240414_171702581.jpg

The idea could work, but the amperage would be too much a good covering Is obtained if less than 0.08 amp are used, a bigger current would for the alpha form of PbO2. The alpha form would not be reliabile and not endure the Cell pH 

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20 minutes ago, kingkama said:

The idea could work, but the amperage would be too much a good covering Is obtained if less than 0.08 amp are used, a bigger current would for the alpha form of PbO2. The alpha form would not be reliabile and not endure the Cell pH 

Yea I don't know if I'd want to make lead dioxide anode myself anyways, as you can just buy it from China. I speak of using it for making chlorate/perchlorate. The picture shown is just cathode. I cut a slot into the Ti stick and just jam the plate on, and then tack weld it together. Fusion weld only because Titanium filler rods are expensive. Really Titanium welds like stainless steel, uses the same process (DC TIG welding). I just blast it with very high current (about 150 amps), and make sure the argon flows for at least 10 seconds.

Most stick welder can go down to about 10 amps or so. My trouble with using a computer power supply is you have no control of the voltage or amperage.

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15 hours ago, kingkama said:

The idea could work, but the amperage would be too much a good covering Is obtained if less than 0.08 amp are used, a bigger current would for the alpha form of PbO2. The alpha form would not be reliabile and not endure the Cell pH 

 

15 hours ago, taiwanluthiers said:

Yea I don't know if I'd want to make lead dioxide anode myself anyways, as you can just buy it from China. I speak of using it for making chlorate/perchlorate. The picture shown is just cathode. I cut a slot into the Ti stick and just jam the plate on, and then tack weld it together. Fusion weld only because Titanium filler rods are expensive. Really Titanium welds like stainless steel, uses the same process (DC TIG welding). I just blast it with very high current (about 150 amps), and make sure the argon flows for at least 10 seconds.

Most stick welder can go down to about 10 amps or so. My trouble with using a computer power supply is you have no control of the voltage or amperage.

You can control amperage e voltage with a multimeter, but for the same cost you can buy a controlled Power supply, also the Lab Little One with a peak of 10 amps Is more than you need for the firsts batch

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