Sciencemadness Discussion Board - More on PbO2 electrodes

More on PbO2 electrodes

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Picric-A - 18-8-2008 at 10:50

nope, in myn it looks like a black powder attached to it, when i rub it wet it comes off as a graphite like mark on your finger, when dry it seems to stay on, again like rubbing a pice of pencil lead on the side, only a bit of black comes off...

dann2 - 18-8-2008 at 11:37

Hi,

Not a hope of this working. The Lead substrate will get attacked from the start and the whole lot will fall apart.
It has been tried many times before my many hopeful Chlorate/Perchlorate makers. You will probably get some Perchlorate to form before the anode fails but you will get damm all.

Dann2

......and ya need not bother with the Iron either..........LOL

hashashan - 19-8-2008 at 00:40

What do you mean not bother with IRON?
I know a dude that grew a massive anode on Iron substrate

dann2 - 19-8-2008 at 02:45

I meant using Iron as an an actual current carrying substrate (in a Chlorate or Perchlorate cell). OK as a substrate for a massive anode.

Dann2

chief - 16-9-2008 at 03:06

Has someone tried this (?) ::
==> since the probloem with the PbO2-Anode is it's mechanical disintegration,
==> why not just put the PbO2-flakes into a cup (that rests at the bottom of the chlorate-cell),
==> and contact this cup, full with the PbO2, somehow ?

So the PbO2 wouldn's "fall" off, since gravitation could not drag it any lower, and the anode could be useful like that ...

For the contacting may be a goughing-rod, insulatat over most of it's path, and only electrically connecting from somewhat within the PbO2-ground, could suffice (?), like eg. leading the goughing-rod throug a glass-tube down to the PbO2.

Since electrochemical things only appear where the current flows, and the potential is shielded by conductors (as the PbO2), the eletrochemical reaction would just take place at the surface of the PbO2-bed, shielding the underlying PbO2 nd the graphite as well as the conductivity of the PbO2 allows: The better the conductivity, the better the shielding effect ...

Besides also the graphite, when corroding, just would end up within the PbO2 (contributing to the conductivity somewhat), maybe slowing down the corrosion-rate too ?

hashashan - 16-9-2008 at 03:20

Well I dont know where to start but my main pioint will be that it is imposible
the reasons would be :
1)water is not vacum, the powder will leave the cup and stay as suspension due to water currents and bubbles forming on the anode and inside it

2) PbO2 is resistant to the conditions in the cell but the powder is inferiour to the single ingot in resistance

3) the electrical resistance of the powdered ande would be enormous, heat will be evolved and once again your anode will just float around

4) graphite will get worn down in an hour once you hit the perchlorate stage

however if you press your anode most of the problems will dissapear.
I dont know how a pressed PbO2 anode will work but AFAIK it also doesnt work

chief - 17-9-2008 at 08:06

What about this:
==> When ppt. out the KClO3 from the NaClO3-NaCl- electrolyte ::
==> using just KOH instead of KCl, because of its high solubility

Benefit would be to have just to acquire only the KOH, no KCl (with little other usefuleness) necessary. The after-ppt.-electrolyte would then be more alcalic (affecting the efficiency, as I believe to have read elsewhere), but otherwise not much different from the usual XClO3-manufacturing scheme, where also someways anyhow an hydroxide-solution is reacted with chlorine ... ???

Do am I not aware of some difficulty ?

chief - 17-9-2008 at 08:25

Also: Since I didn't find any KOH or KCl until now, but a bag of K2SO4/MgSO4 (70/30), my raw plan is:
==> Mg out as MgCO3, via Soda
==> use the resulting Na2SO4/K2SO4 (70/30) to ppt. out the KClO4, with some loss ..

I don't care too much about the loss, but how is it:
==> Could the electrolyte be re-used (?), containing now also SO3(2-)-ions ?
==> might it even be better to at first not ppt. out the Mg, and thereby have some Mg getting into the reaction, which gives even more soluble Chlorate than Sodium (http://en.wikipedia.org/wiki/Solubility_table#M), which at the end might give a way to obtain NaClO3 by ppt. out the Mg at last (via carbonate again)

chief - 19-9-2008 at 04:23

Report: I have a PbO2-Anode in Service, after only the second attempt to make one:
==> It operates since 24 h, at 10 A, with no loss of material

Was made like that:
==> 13 mm-carbon rod (welding), copper plated
==> was hung into the Pb(NO3)2 -Bath, (_little_ acidic, more than 200 g/l, temperature 10-20 [Cels]
==> initially 60 mA/cm^2, after 5 h down to 20, for 12 more h
==> every 3 h PbCO3 was added, just so much as would quickly dissolve on it's path down the vessel (cola-bottle, ca. 1.2 l volume, Kathode: copper-wire (2 mm diameter, as spiral, 0.75 winding/cm))

Although th finished Anode lookes suspicious (pin-needle-head-like "pinholes") it holds and does not corrode ! After 24 h maybe its not that great, but at least it can be called a "hardened" graphite-electrode !

The welding-graphite-electrode was copper-plated and hung into the bath as it was, with the copper. The copper dissolved during the initial 1 h, then the PbO2 took its place. Thereby maybe I just re-used the proper-graphite-preparation (for plating) that was applied by the manufacturer (who plated the copper).

... and the anode was rotated during the plating, but not at 1000 rpm, just every 10 seconds a slight 0.3-seconds start to the drilling engine, in which it was mounted. Only enough movement to keep the bath stirred and to potentially shake off larger bubbles.

[Edited on 19-9-2008 by chief]

[Edited on 19-9-2008 by chief]

tentacles - 19-9-2008 at 19:21

I've been considering purchasing one of the commercial MMO anodes and attempting to plate it with PbO2, as an experiment. The 2x6" ones are only $49 from americanpyrosupply.com so it wouldn't be a gigantic loss if it was a failure. Thoughts from others? I've heard these anodes CAN make perc but likely erode faster than one would like. The PbO2 coating over top might work well, similar to how dann's PbO2 over ATO has been working out so well.

chief - 20-9-2008 at 00:05

But welding-rods (13 mm diameter, 40 cm length, copper-plated) cost below 1 EUR each ! Thats cheaper, and after the 50 EUR for a MMO-electrode probably by variation of the parameters anyone can get around using the graphite, and with an increasing success-rate !

hashashan - 20-9-2008 at 02:48

cheif you are right, however the problem will begin as soon as a single pin hole will reach the substrate, graphite erodes extremely fast when you are trying to make perchlorate with it, i mean it will be a matter of several hours untill your anode will become absolutely useless.
The only test you can make is to try to make perchlorate with it with low chloride amounts, then you will know if it functions or not.
the fact that it is working in a NaCl solution doesnt say anything yet

dann2 - 20-9-2008 at 14:10

Hello,

Ye old Graphite substrate Lead Dioxide anode....AGAIN!!

My two cents worth on Graphite substrate anodes:
Use a thick coating of Lead Dioxide, at least three mm, better to use 5mm.
Keep plating conditions as professional as possible (two big tanks, steady pH, steady Lead Ion concentration, use surfactant, etc) so that the coating is good.
Use high grade of Graphite. Gouging rods

(if you can get them to work that would be great)
Many have made the Graphite Substrate LD Anode,
Few have actually got the (damm) thing to work for long.

I think that plating an MMO would be interesting to see if it would work (don't see why not). US patent 4444642 says it can be done, it is the only patent I know that states it can be done, but there are many types of MMO. When LD plating wears off (hopefully after much Perchlorate has been made), just plate on more LD again.

If the LD plating fails quickly (ie. the anode does not work at all) you always still have your MMO anode for Chlorate etc. I would not think that plating with LD would actually damage the MMO coating. There would be no loss at all from trying!!! (Go for it tentacles, grab the bull by the horns!!! (as it were), it's the only way we will find out.
Coating Titanium with Tin Oxide is a bit of a pain, especially if you do not have any SnCl4 (Stannic Chloride, anhydrous or otherwise).

@Chief
You might be tired by the time you have all the different parameters tried. The one dollar Gouging rods are cheap but what about all the chemicals, time etc.
Graphite substrate LD anodes DO work. There were used by Kerr/McGee? to make kilo tons of Perchlorate (See US 2,945,791). The amateur has, by and large, failed to get this type of anode to work. It can be done though.

@ Tentacles
Where did you read/hear that MMO will make Perchlorate?
JP Smith has suggested that Pt Oxide (not a very usual Oxide type in MMO as far as I know) in an MMO anode may/would make Perk.
________________________________
Edit:
Patent for Perchlorate MMO Anode.
US Patent 4267025 depicts an MMO anode made from Ti, Platinum Group Oxides + Tin Oxide that is suitable for Perchlorate production.
______________________________

Really must crank up a cell with LD anode again soon.

Cheers,
Dann2

[Edited on 21-9-2008 by dann2]

chief - 25-9-2008 at 10:39

I don't want to brag around, but I just have to:
==> now, with the above setup, I also made a very dense and smooth anode, that has only 1 pinhole, and gives no black color when wiping it

This time the electrolyte was thicker, and I had plenty of PbCO3 to throw in, for neutralizing most of the acid.

DJF90 - 25-9-2008 at 11:09

PICTURES PLEASE

chief - 25-9-2008 at 12:05

Sorry for the lousy quality of the webcam; here 3 images, each as attachment (since img-code has to name a url):

pbo2-2.png - 35kB

chief - 25-9-2008 at 12:06

the next:

pbo2-1.png - 44kB

chief - 25-9-2008 at 12:07

and:

pbo2-3.png - 43kB

chief - 25-9-2008 at 12:15

And it weigths 77 gm more than another of the same sort (but with the original copper-coating in place)
The plating lasted maybe 6 hours,
==> current was 4.5 A,
==> current-density anbout 65 mA/cm^2 at the start,
==> than diminishing with the growing of the layer (maybe 2 mm thick)

dann2 - 26-9-2008 at 17:20

Hello Cheif,

Patent here:
http://www.freepatentsonline.com/4702805.html
that mentions Sulphate in the solution.
May be of some use regarding what you asked up a few posts.

Dann2

gregxy - 29-9-2008 at 17:00

There were some hints at this earlier but why not try the
following:

1. Get a cylindrical plastic container with a flat bottom.
2. Get a Pt or Pt plated wire
3. Drill a hole in the bottom of the plastic container the same dia as the wire.
4. Inset the wire through the hole and coil it to form a flat spiral in the bottom of the container.
5. seal around the wire with some form of glue.
6. Put about 2cm of PbO2 into the container.
7. Press the PbO2 to form a solid mass.
8. Plate additional PbO2 into the mass if needed.

This would allow you to create a truely massive electrode.
In addition the vulnerable connections are protected and any
PbO2 that flakes off should just stay in place.

It has a final advantage that the Cl2 that is generated will bubble up to the cathode, (which could be just a flat metal disk 1cm above the anode.)

tentacles - 29-9-2008 at 17:21

I think that if you can afford a piece of Pt wire that will handle the kind of current we're looking for (just as a simple conductor) then you don't need the PbO2 in the equation. Also, I have concerns about the oxygen and chlorine evolving preferentially on the Pt, when the solution inevitably penetrated the cracks and pitting.

Using a Pt plated Ti mesh anode as a substrate for PbO2 might work, though... but you're talking about a $100+ substrate. That makes a good anode by itself.

Please, go read that patent about pressed PbO2 anodes. It's getting kind of old, everyone always dredges that up. I'm guilty of it as well. You MUST plate over the pressed PbO2 - period. The powered stuff is the wrong phase. It crumbles. You have to press it (with a composite binder) at thousands of PSI. And even then, you STILL need a perfect PbO2 plating process, or a substrate that can handle the cell chemistry as anode.

Also, that advantage of Cl2 and O2 bubbling up.. also means that every bubble under the cathode is obstructing your electrons.

dann2 - 21-12-2008 at 18:57

Hello,

I seen the attached paper referenced many time but never actuall read it. It the original spinning Graphite substrate anode procedure form the Bulletin of the Chemical Society of Japan. It is available freely from their web site.
Interesting to note that they used Dichromate in a Chlorate cell and still got an OK CE. Guess Dichromate is not totally detrimental to CE in a Lead Dioxide anode Chlorate cell.

Attachment: Bulletin of CS Japan.pdf (748kB)
This file has been downloaded 1729 times

dann2 - 25-6-2009 at 10:05

Hello,
A paper here from the Bureau of Mines of a Ti substrate LD Anode from http://www.hathitrust.org/.
It is for electrowinning metals. Not much in it, it seems that we have not seen before. It uses Ti with holes drilled in it for the substrate. It also uses a high level of Nitric acid in the plating bath. Happy reading.
Dann2

Attachment: Bureau of Mines LD Anode.pdf (845kB)
This file has been downloaded 1043 times

tentacles - 7-10-2009 at 15:34

Very minor addition to the gene pool here, turns out nonionic surfactant is dead easy to come by, simply purchase Jet Dry rinse aid. 1-5% c10-16 ethoxylated alcohols... CAS 68002-97-1. No idea if this would be suitable for LD plating but it could be a very accessible source.

The END has arrived

dann2 - 12-1-2010 at 15:25

Hello,

Thought I would stick this in this thread since it's LD.

My Ti substrate LD Anode was shelved for approx. 6 months and then placed into a Perchlorate cell from a previous Graphite Anode cell (liquor which was taken to 30 grams per liter Sodium Chloride from a saturated solution of Chloride). It ran for approx. 3 weeks at 1.75 Amps until the last of the Lead Dioxide fell off. The Lead Dioxide fell of in two slabs of approx. 1.4cm squared each. There were no drilled holes in the Ti substrate at the top of the Anode where this LD was. The thickness of the LD that fell off was measured to be approx. 1.3mm. This compares to a starting thickness of approx. 1.5mm in that top area when the Anode was new. There was no visible erosion of the Ti substrate. The cell contained no Fluoride which was blamed for Ti erosion in the previous cell run. There are still parts of the Anode with LD still clinging to it around the holes etc. There are also areas of the Ti which still have Tin Oxide on them as they are gassing when current is passed. The Anode still draws 1.75 Amps funny enough. Tin Oxide is tough stuff. No tests for CE were made. Some brown deposit of LD can be seen on the cell bottom.

The Anode has clocked up a total of 4.7 months in various cells.
It's time to make a new one!

Previous adventures and all guresome details with this Anode can be seen here

Dann2

[Edited on 12-1-2010 by dann2]

Swede - 16-1-2010 at 12:57

Dann2, what effect (if any) do you think fluoride has on lead dioxide anodes, or by extension, on the cell chemistry itself? The whole area of cell additives seems to start and end at dichromate and fluoride, and this is one of those areas where, unless the cell chemistry is well known, it is hard to determine what effects these additives have. If there is a helpful additive that can be removed during purification, and isn't overly toxic, it'd be very helpful.

I need to get off my rear and try welding up some suitable frame-like substrates for further LD tests.

Rosco Bodine - 16-1-2010 at 20:43

Quote: Originally posted by Swede

I need to get off my rear and try welding up some suitable frame-like substrates for further LD tests.

Bismuth may be a thing to keep in mind there .......oh the beauty of hopper crystals , maybe it's a clue to see a rainbow there with sacred geometry

All Aboard
http://www.youtube.com/watch?v=dBawQqcNfog&fmt=18 Still Searching

[Edited on 17-1-2010 by Rosco Bodine]

dann2 - 17-1-2010 at 11:01

Hello,

If using Titanium substrate anything, Flourine is out IMO.
There is a paper (Perchlorate making) here giving info. on using Persulphate as an additive. It also uses Sulphuric acid (and both F and Sulphate) to both lower pH and as an 'additive'. The paper says that pH effects CE and also how effective each additive is. I have read papers that say the opposite, ie. pH has no effect on CE. It's all rather complicated and it depends on Anode age, CD, temperature etc etc etc. I am not up to speed on the best conditions to use for (say) a bucket cell, or indeed any other design. They also say that high pH gives LD erosioin (bad, very bad IMO).
Chromates form a film on the Cathode that keeps Chlorate, Hypochlorite, Perchlorate etc away from the Cathode but allows water and hydrogen through.
It also acts as a pH buffer and lowers Oxygen generation at the Anode. According to a thesis my Linda Nylen (spelling) that was uploaded here somewhere, Yttrium compounds will do the same job and are not toxic.
Chromates are out for use with LD (don't know about Y) as they form a film on the LD which lowers CE.
F does the same as Chromates, don't know if it forms a film on the Cathode or what.
Don't know how Persulphates work.

Link here to a patent that uses Persulphate as an additive for Perk making. It uses LD. The use of Persulphate seems to be associated with LD and Perk making.
I don't really know if Persulphate is a useful additive for Chlorate making or with what Anodes.

My own attitude to additives is to leave them out. Stay green. F is definately out for Ti substrate anything. Chromates are toxic. Yttrium not easy to get. Persulphate only helpful (I think) with LD during Perk. making?
Use high current density on Cathodes to help keep reduction of species as low as possible. Remember the CE advantages are not huge in regard to additives. It would be a joke to add additive to a Chlorate cell that is hot pH controlled.
Then again if using an expensive Pt Anode in very clean Chlorate (no Chloride) to make Perk. it seems sensible to add Chromate to help keep Chloride from appearing (reduction of Chlorate) and protect Pt Anode from erosion.

All clear as mud!

Genuine batch processes (like we do) where Chloride (or Chlorate) is added to a cell and that cell is then run to low Chloride (or Chlorate) concentration will ALWAYS give lower, less impressive CE's than quoted for industry no matter what additives or what not we employ.

Swede, why don't you get yourself one of those office chairs with wheels. You can keep your rear end where it is and propell yourself about the garage from bench to bench.......

Dann2

Dann2

dann2 - 20-1-2010 at 16:24

Hello,

One more on LD plating onto Graphite using ceramic particles in the LD plating tank. Tested in Perk. cell too.
Thanks to www.Solo.library.com !

Cheers,
Dann2

Attachment: ld_beads.pdf (526kB)
This file has been downloaded 1462 times

Swede - 22-1-2010 at 08:14

Sulfuric acid seems like it would be an ideal pH controller for a perchlorate cell sensitive to chloride ions. All that would be left behind in the end would be soluble sulfates, which can be removed in the washing/recrystallization process. If a high pH (inevitable with an uncontrolled perchlorate cell) is truly hard on LD (and it wouldn't surprise me) then sulfuric would be a decent option.

I am more interested in additives in a perchlorate cell more as a means of reducing or eliminating erosion that in increasing CE. Chromate are out, I won't use them for this process. If there are easily-removed additives that protect Pt, LD, or both, then it might be worth pursuing.

quicksilver - 6-2-2010 at 11:34

Would it be possible to accomplish two objectives at once with a bar of lead oxidizing WHILE IT IS BEING USED THUS MAINTAINING THE PbO?
It just seems that is not so impossible an objective.

The other thing that struck me (no pun) is that the technique for making Teflon coated bullets could be used with gouging rods with PbO. You would need an oven that someone would not want to cook in ANYMORE however. Powdered Teflon, graphite, PbO and a rod....

[Edited on 6-2-2010 by quicksilver]

Xenoid - 6-2-2010 at 12:38

Quote: Originally posted by quicksilver

Would it be possible to accomplish two objectives at once with a bar of lead oxidizing WHILE IT IS BEING USED THUS MAINTAINING THE PbO?
It just seems that is not so impossible an objective.

Well, it may just seem that way to you.

Do you seriously think industry spent many millions of dollars and over half a century searching for MMO when they could have just used lead anodes. Why would they use expensive platinum in perchlorate cells when they could just use good old lead!

Why don't you try putting a lead anode (even one with a lead dioxide coating on it from electrolysis of dilute sulphuric acid) in a chlorate or perchlorate cell. You'll get an instant messy mix of white, yellow and orange chloride and oxides!.

quicksilver - 7-2-2010 at 08:29

I know next to nothing about this industry specifically, so I can't really maintain a reason for the lack of use of PbO (I simply don't know enough about it) however it has worked for some electro-chemical concepts in the past. My guess is that lead per se' is just a no-no and working with it carry's too many hassles. But for a hobbyist agenda these MAY be overcome.
Actually I was genuinely asking a question because PbO pops it's heavy little head up periodically in these discussions.
Industry has different needs, etc. I was reaching because we appear to be channeled to a choice between MMO or carbon - -yet...PbO continues to come up in discussion regarding cell design. So; it's really a dead-end?

Xenoid - 7-2-2010 at 09:17

Quote: Originally posted by quicksilver

..PbO continues to come up in discussion regarding cell design. So; it's really a dead-end?

No - of course not! Lead dioxide is one of the best anode materials available, able to make chlorate and perchlorate efficiently. Unfortunately, like many coating materials it tends to be porous and will allow underlying anode materials to be eroded unless they are "valve" type metals (titanium, niobium, etc.). Such metals rapidly "passivate" at the point of attack, by becoming coated in a protective, impervious, oxide layer, thus preventing further erosion.

Lead dioxide is a good electrical conductor so if you can make a "solid" LDO anode or coat an inert material (even plastic) readily available to the amateur you will have made an outstanding contribution - good luck!

All your questions have been answered many times over, in the multitudinous chlorate/perchlorate and anode threads on this forum. Have you not read any of them? There are also several fine websites, and many publications online, please avail yourself of them.

[Edited on 7-2-2010 by Xenoid]

12AX7 - 7-2-2010 at 11:52

As far as using Pb or PbO directly as an anode, the latter is not very conductive, while the former does oxidize to PbO2 on the surface, but the interface layer consists of PbO and PbCl2 which are poor conductors. The result is a slowly flaking electrode and very little electrolysis of the solution.

Tim

mnick12 - 3-3-2010 at 15:58

I know little to nothing about electro-chemistry, but I think some of you who have been interested in making our using lead dioxide anodes may find this page interesting http://resources.metapress.com/pdf-preview.axd?code=h5726026... .
It outlines the preparation of both alpha and beta PbO2.

A quick question, it seems as though beta PbO2 is preferred over alpha PbO2, why is that? Is one more durable than the other?

Contrabasso - 4-3-2010 at 11:12

Years ago I worked in a big plating shop. The "Chrome" was put on in a huge automated machine. The plating order was (on top of steel!) flash nickel for adhesion, levelling copper for its ability to level the surface (saving hand buffing) then three nickels there were three slightly different nickel baths and they plated different grain sizes so that there was almost no porosity in the nickel then the top coat was bright chrome.

Now I haven't access to the plant (it's gone and rebuilt as houses!) but if anyone can relate the grain size variants to the properties of led dioxide plating system, could one plate three adhering but different layers to protect the substrate more???

quicksilver - 4-3-2010 at 11:53

Would not grain size variety need a micron measurement slide for a decent microscope? Else you'd be dependent upon things like "mesh" measurement which can be all over the place.

I am really struggling with switching power supplies. The more advanced, the more difficult to understand them with no background paperwork. One of the MOST frustrating things is that I have found problems I could have eliminated had I be much more professional in my wiring and simple matters. The excitement to get something up and running is slowing me and it's a real bastard.
One thing that I have come to understand is that Lamda (the company not the man) had bought out MANY struggling companies in Calif. and there are LOTS of good stuff out there (especially from the late 1980's) with NO paperwork. A lot of the rack mounted PSU and the heavy duty units designed for automated plating shops have differing sensor mechanisms.

IF you found a Lamda rack mount that reads in the tenth of a volt with no load and applying a load of 10w brings it up, you can then hook up the unit to your cell and the current will jump when the load is retrieved from the 5v output. HOWEVER there are some that lock at that current (Ratheon's Sorensen 5-30). To unlock the current sensing (you need a DIMM in line at the 10A plug) have some higher load like an auto interior light bulb & put that in place of the DIMM (or you'll screw your DIMM as it will jump to it top and drop down to what resistance it sees (there is a formula for this which I don't know)

I also discovered something about the use of computer PSU's for this application. SOME units will cheat you out of current if you bunch the + leads together. This does not occur on ALL computer PS what so ever. But some should be checked. I found one 400w that had this issue with the ground (bunching them to form a single negative lead). I have found out a hell of a lot of things by learning from Woelen's original design; which I have come to appreciate more and more. In fact, had I not found a electronics surplus and scrap yard I would defiantly get one of those 1000w supplies knowing what I do now. Those things can be made to continually pump 30A with NO problem!

[Edited on 4-3-2010 by quicksilver]

dann2 - 4-3-2010 at 12:36

Hello,

The full article is attached if anyone is interested. It's a djuv file and you will have to download a reader for to see it.
Regarding the Alpha/Beta my understanding is:
The Beta is stated to be the best wearing coat. It has higher conductivity too but I do not think that is really an issue as both have very good conductivity. The Beta may have higher catalytic activity (better Current efficincy and will make the products at a slightly lower Voltage that Alpha, thought that's a guess). The Beta is always used by industry.
I have seen Alpha on a Ti substate Anode exposed when the Beta fell off and it still worked away OK and lasted quite a long time. It was only a very thin coating put on first as it is supposed to adhere better that the Beta.

Dann2

Attachment: AlphaLD.djvu (230kB)
This file has been downloaded 778 times

alternating layers alpha PbO2 and beta PbO2

Rosco Bodine - 13-5-2010 at 15:50

It would seem possible that a stress relieved PbO2 anode can be formed simply by varying the temperature of an electrolyte which produces the alpha or beta modification
as a function of temperature. It would also seem possible that at an intermediate temperature a mixed deposit of the alpha and beta may simultaneously be produced. Although these processes were not described, that is a reasonable conclusion which may be drawn from the attached article.

A request is pending for the related later article from this past December which describes the beta PbO2 process.

A couple of ideas have occurred to me during the break for awhile in the discussion of plating schemes for PbO2. In the processes using lead nitrate electrolyte, there is a use of copper nitrate and nickel nitrate and sodium fluoride as minor ingredient additives. I have some reservations about
these particular additives. It occurred to me that it may be useful more than nickel nitrate to use cobalt nitrate instead,
as a likely substitute, or perhaps manganese nitrate. Also
it would seem that any use of fluoride should be the ammonium salt and no fluoride whatsoever should be used in combination with any bismuth compounds in the electrolyte due to the likelihood of precipitation of the virtually insoluble bismuth fluoride. It seems that bismuth
oxide could be applied as a pore filler sort of trace catalyst
on a PbO2 anode coating as a finishing step, and part or all of the bismuth oxide transformed into the fluoride chemically simply by a final dip in a fluoride solution. There possibly could be a catalytic bielectrode effect produced by the couple between the PbO2 matrix and the Bismuth Oxide / Bismuth Oxyfluoride / Bismuth Fluoride deposits in the pores.

Attachment: The electrodeposition of highly reflective lead dioxide coatings.pdf (423kB)
This file has been downloaded 2007 times

Here is the second article which describes the beta PbO2 electrodeposition at 60C.

Interestingly enough Bismuth is also capable of forming a concentrated solution or sol in a methanesulfonic acid aqueous system. See US6103088 attached. There are obvious implications here in these references for the usefulness of methanesulfonic acid in processes for production of anodes, electrolytical processes obviously.
But it would seem also that a methanesulfonate of bismuth
and perhaps other materials of interest as dopants may have interest with regards to baked coatings.

[Edited on 14-5-2010 by Rosco Bodine]

Attachment: The deposition of nanostructured b-PbO2 coatings from aqueous.pdf (642kB)
This file has been downloaded 2412 times

Attachment: US6103088 Bismuth Methanesulfonate.pdf (45kB)
This file has been downloaded 963 times

quicksilver - 15-5-2010 at 07:59

I've followed the above w/ great interest. Commercial availability of Bismuth trioxcide (tech-grade) through pyro supplier chemical outlets is fairly cheap as are nickel & copper nitrate. But most all fluoride/fluorine materials seem to be sold as reagent-grade only w/ commensurate price.

I would imagine that at the point of conductivity with minimal resistance, the percentage of binder would be low enough to allow use of "coating material" (with low % binder such as SL or thinned potting epoxy). "Baked" coatings also appear attractive as to be a less time & $ intensive route.
It just seems a damn shame to spend so much time on effective coating and see it all fall away after a few runs w/ high current. What's more at the level needed for proper solutions the price tag's not low either. To loose the coating after, say, half a dozen runs is tough. For that matter, what's the longest anyone has had a (DIY) coated anode stay coated for?
I have (somewhere) the conductivity tables of a great deal of materials & have learned via bridge-wireless ignition experimentation how to alter this with highly conductive dopants. It appears within grasp to make a polymer electrode as conductive as needed w/ addition of some % or carbons.
{At this point, Ive gotten some damn nice PSU's and see no need to do runs in small scale BUT have seen the results of higher current on electrodes & at or about >30A they take a real beating if the solution volume is under a certain level. We have seen the electrodes "curl away" from one another on many occasions and this, I believe is one factor to the flaking off of surface coatings. The flat design of an electrode is a double-edged sword.} This curling or warping effect is often due to the distance between electrode being closer than formula - however when distance is met surface area may go beyond what is practical unless simple means are found to mfg.

The use of a cylinder (such as a graphite rod) virtually eliminates the curling effect when proximity of electrodes are closer. Instead of using the flat perforated electrode, several cylinders [of each electrode] would possibly sustain a much longer life.
When it gets down to the nitty-gritty, it seems the coating of several graphite rods or bars may meet expectation of long life and highly efficient operation.

In regards to baked coatings; I have shopped element metals for years now & found that price breaks occur in powdered form (even from high-priced outlets like Alpha Asear). When dealing with oxides, technical grade (99.5% or poorer) are available in only certain products. Using reagent-grade would bring price levels to a very poor return on the investment IF the electrode's life is low.

[Edited on 15-5-2010 by quicksilver]

Rosco Bodine - 15-5-2010 at 15:58

I'll have to look back through the earlier references, but it seems familiar and possibly the use of the same surfactant also benefits beta PbO2 electrodeposition
from a lead nitrate based electrolyte. There may be other electrolyte systems which would also produce a dense and stress relieved mixed allotrope deposit
having high density. While doing some searching for these articles I also read that conducting the electrodeposition of PbO2 in an electrolyte which also contains a sol of a different oxide, such as alumina and possibly other materials
results in an incorporation of the oxide of that sol in mixture with the PbO2, as a kind of matrix. This could produce interesting mixed deposits having desirable properties.

Ag or Ag-Pb alloy substrate PbO2 anodes

Zaratukhshthra - 10-12-2010 at 08:18

US4345987 describes a Pb/Ag alloy substrate PbO2 anode. They claim the use of Pb alloy instead of pure silver increases the resistance against corrosion of the electrode. But their comparative studies (corrosion tests) were done in aq sulfuric acid medium instead of chloride ions (the electrode was not supposed to be used for ClO3/ClO4 preparation).
In the introduction part, there's a brief exlanation of silver substrate PbO2 anodes

Quote:

Japanese Patent Publication No. 23947/16 discloses an electrode obtained by electrodepositing PbO2 on the surface of silver substrate or a metal substrate plated with silver. This electrode has a very small contact resistance between the metal substrate and the PbO2 coating. further, the electrode exhibits a sufficient resisiance against corrosion when it is used for the electrolytes containing halogen, sulfides, chromates and carbonates that form sparingly soluble. silver. compounds, or for the, alkaline electrolytes.

(any Japanese member?)

It's well known that silver is one of the best choices for connecting to PbO2 anodes. this is not because of low resistance of silver oxide intermediate layer (simply because it's insulating) but the formation of a silver plumbate layer.
e.g. in US3017448 (electric battery) lead compounds are added to the active material of a silver electrode:

Quote:

In the presence of alkaline electrolyte, the
silver oxides and the lead or lead compound react to form
a coating on the silver oxide particles which has been
identified as silver plumbate, Ag2PbO3 or Ag5Pb2O6. This
coating or film reduces the gassing rate of a divalent
silver oxide electrode by a factor of about four, substantially
decreases the electrical resistance of such an electrode
and provides an electrode discharge which
[achieves] utilizes almost 100% of the theoretical divalent
silver oxide capacity at the upper voltage plateau.

(P.S. this is my first post. Hello to everyone!

)

Attachment: US4345987A PbAgSLD Anode.pdf (320kB)
This file has been downloaded 831 times

dann2 - 25-12-2010 at 17:56

Hello,

(correct thread this time!)

A good way do find out how the Pb/Ag substrate (when used in a LD Anode) would hold up in a Perchlorate cell (or Chlorate Ccell) would be to make a small amount of the alloy and cast an 'Anode'. Use this 'Anode' in a Perchlorate cell and see how long it lasts. If it lasts quite a long time, (like MMO or Tin Oxide on Ti) then it should be OK for a substrate in a Lead Dioxide Anode.
If it erodes like Graphite then it will not make a good substrate and will be comparable to Graphite as a substrate (a shit substrate for the average garage operator). It will need a perfect coating (stress free, no pin holes, thick, etc) of Lead Dioxide which is not very easy to obtain in the Amateur world.

A substrate that is tolerent of faults in the LD coating is extremly desirable.

Dann2

Nitrites in LD plating tank

dann2 - 5-8-2011 at 14:54

Bump.

Document attached on producing Lead Dioxide from Lead Nitrate and Lead Perchlorate baths. Not much in it but it talks a bit about the problem of Nitrites building up in the tank and causing a drop in plating efficiency.
They say this can be counteracted by adding Hydrogen Peroxide or using Pb304.

There is a graph showing plating efficiency versus 100*Nitrite/Nitrate ratio.
What does this ratio actually mean. If I have 300grams per litre Lead Nitrate and 10 grams per litre Lead Nitrite am I at the 100 X 10 / 300 = 3.3 point on the horizontal?
Thus 10 grams per litre Nitrite gives you about 42% plating CE if you have 300grams per liter Lead Nitrate.
US 2994649 gives a figure of an increase 0.1% Nitrite reducing plating CE down to 30%.
It's impossible (for me anyways) to interpret what the patent is trying to say (or hide).

The Patent mentions Sodium Nitrite (as opposed to Lead Nitrite) but thats just an error IMO or are they bizzarly giving the Nitrite content of the bath in terms of 'Sodium Nitrite'

Anyhow, it's time I STFU and got out the plating tank.......

TIA,
Dann2

Attachment: PB02_NITRITES.pdf (158kB)
This file has been downloaded 1205 times

[Edited on 5-8-2011 by dann2]

watson.fawkes - 6-8-2011 at 05:24

Quote: Originally posted by dann2

There is a graph showing plating efficiency versus 100*Nitrite/Nitrate ratio.
What does this ratio actually mean. If I have 300grams per litre Lead Nitrate and 10 grams per litre Lead Nitrite am I at the 100 X 10 / 300 = 3.3 point on the horizontal?

That's how I read it. The square brackets in the axis label denote activity, which here is tantamount to concentration. The 1.6 mol / L concentration they're using is more-or-less a saturated solution of Pb(NO3)2.

What's interesting, though, is that they mention that the plating efficiency is up at 100% when the cathodic current density is low, ~ 1 mA / cm^2. This seems like the easiest way to deal with the problem in practice, although it does necessarily increase the tank size. Optimum anodic density is listed at 36 mA / cm^2, so maintaining a 36:1 ratio between cathode and anode areas is the minimum.

The authors also mention using buffers to get rid of "residual stress in deposits". I presume they mean mechanical stress on the resulting anode. As this materially affects lifespan, this seems worth tracking down. They reference a paper by the same authors as "in press".

dann2 - 6-8-2011 at 05:52

Thanks for reply.
That artical cost me twenty bucks!!
Its from the Institute of metal finishing. I thought it would be a bit longer and perhaps elaborate on the Nitrite thing a bit more. It's a subject very little discussed in the patents and journals and yet seems to be very important. CE going to very low % is imporatant IMO.
Even in the elaborate patents by Gibbs (plating graphite with LD for commercial use back in the sixties) it is not mentioned. They have anti stress and anti bubble stuff in the tank, namely ctab (cetyl trimethylammoniumbromate, spelling more than likely wrong). They wash the tank contents (literally) using Amyl Alcohol to sweep out byproducts from the breakdown of the ctab as it effects plating badly after some time.
Perhaps the Amyl Alcohol washes out nitrites too? I would be inclined to think not as Nitrites are very similar to Nitrates (it doesent make sence for an alcohol to 'dissolve' nitrite ions to me anyways.).
Perhaps its a detail left out to confuse a patent thief.

Remember that the paper posted above is not in direct relation to Anodes for Chlorate and or Perchlorate but battery stuff.

Dann2

watson.fawkes - 7-8-2011 at 07:44

Quote: Originally posted by dann2

I thought it would be a bit longer and perhaps elaborate on the Nitrite thing a bit more. It's a subject very little discussed in the patents and journals and yet seems to be very important. CE going to very low % is imporatant IMO.

The point they made about nitrites is that it's an alternate current carrier: "the nitrate ion is reversibly reduced to nitrite at the cathode and oxidized to nitrate at the anode". So it's not presence of nitrite as such that causes the problem. Rather, the formation of nitrite is indicative of cell conditions that promote this alternate current path. The amount of nitrite in the bath at any given time is correlated to the current partition between electrons that travel through the nitrite path and ones that travel through other paths.

dann2 - 7-8-2011 at 09:10

Presence of Nitrites may (along with robbing current) give bad coatings of LD (for some unknown reason).
I of course have no idea if Nitrites do indeed cause a decrease in plating quality.

Reading (yet another) paper on Lead Dioxide. (ref section, a 2011 review of LD Anodes)
it states (and I quote):
............and for pure b-PbO2 typical conditions include:
(a) 1 M lead nitrate + 0.1 M copper nitrate (to avoid
Pb deposition and nitrate reduction on the cathode) in 1 M
nitric acid, 333 K, j = 50 mA cm2 then 20 mA cm2;..........

Will the presence of Copper Nitrate in a Lead Dioxide plating bath (using Lead Nitrate) eliminate or decrease greatly the formation of Nitrites at the Cathode do you think?
I have never seem it mentioned or hinted at before, the Cu Nitrate being there to only stop Lead metal being deposited (wasted) on the Cathode.
Perhaps the Nitrites are only a major problem when plating LD from Nitrate baths when Cu Nitrate is not present (like battery applications, or simply making LD as a reagent etc etc).
Funny enough the only (only two that I have ever seen) articles where it mentions Nitrite problems are in a reagent making patent (depositing LD for making reagent) and the paper above (depositing LD for battery stuff).

Thanks for your time.
Dann2

PolarSmokes - 24-8-2011 at 02:11

I was thinking- since so many seem to have a hard time with a perfect coating of PbO2, why not get a somewhat decent coating of PbO2, and find something you can clog the pinholes with in a vacuum? That something COULD be epoxy, but due to it's higher viscosity, it would take quite a long time to suck the epoxy in- also, the epoxy would be prone to chemical attack- I just chose it as a "something" because it more or less demonstrates my idea.

I know it's not perfect, you have to worry about thermal expansion gradients of the two materials to minimize stress; You would also have to have some surface treatment to get whatever is blocking the pores off of the surface. For the second part, removing the "something" off of the surface, techniques such as (gentle) sandblasting still may be enough to cause cracks in the PbO2.

I've thought of sodium silicate for the "something", but it has a number of problems, but it can also solve a lot of other problems...

Now that I mention this, I do seem to recall reading something about coating the surface with it, but i'm too lazy to go back and look, pardon the laze (:

There is the option of leaving it as a viscous fluid within the anode, kept in place by gravity, if it composed (part) of the floor of the cell. But then you have to worry about changes in volume from different states of hydration, and if it would act as an electrolyte. If it did, would the sodium ions be transferred to more cathodic regions of the cell? If so, then sodium silicate for the "something" is a horrible idea. I am just trying to think of a good "something"- preferably "something" that is simple and won't shred the anode from the inside out.

dann2 - 25-8-2011 at 14:12

All 'pin hole problems' have been solved with the arrival of the fault tolerant substrate
(MMO on Ti, Tin Oxide on Ti and others).
Stay away from Graphite. It's been giving Lead Dioxide Anodes a real bad name for the last twenty years, which is enough to make any grown man (not to mention a Lady!) weep.
Dann2

PolarSmokes - 27-8-2011 at 00:51

what about tin oxide on glass?

dann2 - 7-9-2011 at 16:34

Quote: Originally posted by PolarSmokes

what about tin oxide on glass?

With all non conducting substrates you are back to the problem of obtaining a good permanent connection to the Anode when it goes into service. The only way to do this is to use a Silver metal connection (paint or plate or perhaps wire).
The Lead Dioxide at the top end must carry all the current going to the Anode. You are better off with a conductive substrate IMO. Thats not to say it will not work.

I started to plate some Lead Dioxide today and after some time I tested the tank for Nitrites (Nitrites form at the Cathodes and are undesirable) and got a positive. I commenced to add some Hydrogen Peroxide (recommended here and there for the removal of Nitrites from a Lead Dioxide plating tank) to the plating tank and got a mass of bubbles coming to the surface. It appears that the solution was attacking the plated on LD. That is where all the bubbles were coming from. There was a tiny piece of LD at the bottom of the tank and it dissolve away.
Looks like you cannot do anything about Nitrites in the tank while plating is going on.
Thats a bummer!

Dann2

dann2 - 9-9-2011 at 13:48

I had to abandon ship with my latest effort at coating a Tin Oxide coated Ti strip.
The Alpha (first coat of LD), which is put on using a Alkaline bath when on very badly. It only went on in places on the substrate for some reason or other. When I started with the Beta bath (Lead Nitrate bath) the coating went OK but the set up I had let me down. Bubbles kept appearing in a siphon tube and I had to stop. Will need to set up a new rig.I
The Anode has a coating of LD on it so I decided to try in out in a Perk. cell just to see how long it lasts.

I also wanted to try out an idea seen over at AmateurPyro.org for attaching connections to Anodes. It looks as if you do not need to weld Ti straps to Anodes, simply attaching the Ti strap using bolts or rivets will do. The fact that solution gets between the strap and Anode does not seem to effect the flow of current . Hydrogen dopeing I guess must be keeping all the Ti Oxide conductive (both on the extension strap and the Anode coating or the Anode (Ti) sutstrate).

The picture attached shows the original Platinum coated Ti Anode + strap from AmateurPyro.
With my Anode + strap I simply bolted an extension Ti strap to the top of the LD Anode Ti substrate and submerged the Anode and bolted connection underneath the Perk. electrolyte where it has been working away quite happily now for about 8 hours.

Some pictures of LD Anode are in zip.

Attachment: Anode.zip (357kB)
This file has been downloaded 731 times

[Edited on 9-9-2011 by dann2]

MOTHER OF ALL ANODES

dann2 - 17-9-2011 at 16:03

Hello,
Just finished plating an Anode.
Seems to be OK.
Hopefully it will work for years?
Details enclosed in attached zip.

In relation to the last (very bad) Anode I made (few days ago) it worked for a few days in a Perk cell before I removed it. It was hard to know if the Tin Oxide or the LD was the active coating as the LD was chipping off. As a test I riveted a piece of Ti to it using a homemade Grade one rivet and it worked OK. No need for welding etc. A Grade five screw corroded.
See picture.

Dann2

[Edited on 18-9-2011 by dann2]

Attachment: cu.zip (394kB)
This file has been downloaded 746 times

[Edited on 18-9-2011 by dann2]

dann2 - 21-9-2011 at 06:28

GRANDMOTHER OF ALL ANODES

Hope I am not 'done' for double posting!

Cranked up anothe LD Anode. The substrate is 'LaserRed' (ebay seller) MMO, which was 1.6mm thick. The openings were 7.5 by 3mm. Coating thickness is about 1.75mm of LD, probably should have let it coat for longer. I used a two tank system. Flow rate between tanks was 17ml per minute per Amp (revised up from the last
Anode I made). pH of plating tank hovered around one. Constant current power supply used. Plating tank was stirred with a magnetic stirrer bar and the Neutralizing
tank was stirred using an aquarium air pump and air stone (a magnetic stirrer bar would be much better). Temp. around 67C.
Cable ties and silicone sealer are not compatabil materials for an Lead Nitrate plating tank. Don't use them. The containers were polyethyene and the filter cloth was
polyester.
Plating for this Anode started off at 60mA per square cm for two hours, 30mA/cm^2 or half an hour and the rest (about 22 hours) 20mA per cm^2.
Some red Lead was added to the Neutralizing tank to counteract Nitrites (not too sure if they are even a problem). 6 hours into plating session no Nitrites
were showing up in the plating tank as shown by an aquarium test kit. Lead Carbonate + Copper Carbonate Hydroxide was added to Neutralizing tank as a slurry/paste.
Some Cu Nitrate was added to the plating tank now and them as Cu was getting low (blue colour disappearing).
Some pictures in zip.

Attachment: cats.zip (1.1MB)
This file has been downloaded 752 times

Griffin - 27-10-2011 at 15:24

Hello,

Sorry if this is a stupid question. Are there companies that manufacture PbO2 anodes?

Many thanks

dann2 - 27-10-2011 at 18:54

'Patsroom' was selling them here some time ago.
Try www.amateurpyro.com

Dann2

dann2 - 9-12-2011 at 15:58

Hello,

Been running two Lead Dioxide Anodes for some time now (2.5 months) as posted in 'Thoughs on Anodes'.
Blow by blow (by blow by blow) details are in the files attached.
They are the same two files as was attached in a previous post with some more
info. added.
The bottom line is that the Anodes are working well. They are suffering very
little wear in the tasks that they are being used at. The larger Anode (187g)
has lost 3.8 grams and the small Anode (84g) has lost 0.5 grams.
The Ti/Tin Oxide substrate Anode was used in Perchlorate cells to 'scavenge'
Chlorate, that is, running the cells from approx. 20 grams per liter Chlorate
to less than one gram per liter Chlorate (high concentration of Perchlorate).
This is a low current efficiency process but is better than using Chemicals
to destroy residual Chlorate IMO.
The other Anode has an MMO on Ti substrate and it was mainly running in
Perchlorate cells that were started with approx. 100g/l Chloride + 500g/l
Chlorate and ran all the way to below one gram per liter Chlorate.
This role causes the most wear but it is very small.
%CE is low at around 40% when Chlorate concentration is high. Don't know why.

Stirring does not seem to help when Chlorate 'scavenging'. I have used Persulphate
and H2SO4 as an additive but I don't know if it helped or not.

Acid demands (to keep cell around 7) is very high in a Perk. cell from
approx. 20 grams per liter Chloride (high Chlorate conc.) to a day or so
after all Chloride is gone. Anyone know why this is so or what is escaping
from the cell to cause pH to go up?

I have yet to run a 'proper' Perchlorate cell. A cell with both high
concentration of Chlorate and Perchlorate (no Chloride).

Dann2

Attachment: LD.rar (423kB)
This file has been downloaded 666 times

dann2 - 30-12-2011 at 23:15

Hello Folks,
Anothe paper here using Gold coated Ti as the substrate for Lead Dioxide.
Dann2

Attachment: Ti_GOLD_Pb02 Anodes.pdf (283kB)
This file has been downloaded 922 times

Exploding Perk. cell

dann2 - 11-1-2012 at 17:20

I checked the pH of a Perchlorate cell today (3.8 liter size)and it was 11.0 so I decided to add some 12% HCl acid. I add it by putting it in a small container which drops the acid into the cell over a five minute period approx.
After adding approx. 50cc acid the pH was only down at 10.5. Started adding another 50cc acid and after about 20cc had gone in, the cell exploded. The lid consists of a piece of thin perspex sitting on top of a container. The lid is not actually attached, just sits there. The lid was also slid to one side to allow addition of the acid.
I was standing close by, and only I was, I probably would never have known there was a bang. It was similar in loudness to when you break a hot incandence bulb (light bulb) if you accidently spray water onto it (or perhaps a bit louder).
A puff of (I presume) water mist came out from under the lid. The lid was not blown off and the cell continued to work OK.
The electrolyte was very yellow in colour, (more yellow than it was before I started to add acid) and I think it may have been caused by ClO2.
There were no sparks or red connections to ignite Hydrogen or a mixture of H and Cl gasses.
Anyone any suggestions as to what may have caused it?

Dann2

Pulverulescent - 12-1-2012 at 02:01

Quote:

'Patsroom' was selling them here some time ago.

IIRC d2, the consensus here was that the Indian manufacturer involved used PbO2 coatings that were much too thin and fragile for sustained perchlorate synthesis for the amateur . . .
There are, I think, a plethora of companies in India making PbO2 anodes for industry!

P

watson.fawkes - 12-1-2012 at 05:03

Quote: Originally posted by dann2

Anyone any suggestions as to what may have caused it?

Does the cell have a stirrer or recirculation pump? If not, there's a class of reactions to be considered that occur in acidic environments.

Pulverulescent - 12-1-2012 at 07:37

Something similar happened me once d2; for expediency I'd just drop in some undiluted acid from time to time, but I accidentally added too much one day and the electrolyte bubbled and fizzed furiously for a few seconds.
There was a slight mist emitted through the vent and it was very lacrymatory!
The vent on a gallon cell should preferably be at least 1"dia.!

P

Pulverulescent - 12-1-2012 at 07:43

Quote:

Does the cell have a stirrer or recirculation pump?

With electrodes reaching close (3mm) to the floor of the cell, H2 evolution at the cathode is enough to provide the necessary circulation . . .

P

dann2 - 12-1-2012 at 10:25

The cell in question has the Anode and Cathodes going close to the bottom so I do not believe there is a 'dead layer' at the bottom.
The electrolyte was very basic (up at 10.0) when I add the acid yesterday.
The appears to be some buffering going on when adding acid to Perchlorate cells. The cell was at a pH of eleven (yesterday). I added 50cc of 12% HCl acid and pH went down to 10.5. (I added some more and the small explosion occured).
Today the cell was back up at 11.5.
I added 50cc acid and the pH went to 5.5.
The quantity of acid needed to control pH seems to be eratic.
My pH monitoring and acid additions are very eratic too. I would need to monitor pH more consistently.

Today the electrolyte did not turn a very yellow colour when I added the acid. I stated that the electrolyte DID turn very yellow when I added the acid yesterday but I am not too sure about that now.
There is some Chloride in the cell that is going in with the (homemade) Chlorate solution that I am addding to the cell which complicates (I guess) things even further.

The only reason that I bother to add acid at all is that I read somewhere that Anode dissolution (Lead Dioxide) has been observed when pH goes above 11. Don't want any Anode dissolution. Have not observed any yet even though the cell has been run for periods of time a a high pH (10 to 11.5)

Dann2

[Edited on 12-1-2012 by dann2]

Pulverulescent - 12-1-2012 at 11:36

Hmmm, have you tried adjusting the pH with the electrodes out of the cell and the electrolyte at RT?

P

dann2 - 30-1-2012 at 14:23

I made some Perchloric acid and it seem to be the 'real macoy' (good stuff) when it comes to controlling the pH of Perchlorate cells.
I set up a pump to pump HCl acid into a Perchlorate cell to keep pH low and all I got was lots of explosions, horrid smells, and a cell with a high pH once the acid had stopped pumping for a few hours.

My smaller Lead Dioxide Anode has come to its end rather suddenly. I put it into a Potassium Chlorate (not Perchlorate) cell to run up some time on it and it split apart. See attachement.
This file is a a file that was attached above with some stuff added to the end of it.

Dann2

Attachment: tiatold_3.zip (70kB)
This file has been downloaded 667 times

pH in a perchlorate cell

gilbert pinkston - 30-1-2012 at 17:19

you dont have to control pH in a perchlorate cell
where did anyone get that idea?

dann2 - 31-1-2012 at 12:17

I agree there is little or no point in controling the pH of an Amateur Perchlorate cell. It is not needed as far as current efficiency is concerned. There may be small gains to be had if you are running under specific, will controlled circumstances. (see link) Most commerical Perk. cells are pH controlled as stated in the Book 'The Perchlorates' by Schumacher (perhaps a cousin of Michael, who knows!)
I think that the pH may be controlled for reasons of equipment corrosion (pipes, tanks, the crystallizer section etc) or perhaps Anode erosion. I don't really know myself.

I have read in JES Aug 61 page 801 (link) that 'dissolution of the Lead Dioxide Anode occured when the pH went above 11'
I have never seen dissolution of my Anodes even though the pH was very high (above 11).
I was adding some HCl just to see how it went. If there is much Chloride in the cell you CANNOT controll the pH using HCl acid AFAICS. You would need Pechloric acid (hardly much point in bothering anyways).

The same paper describes problems when there is too much Chloride in the cell too.
(table close to end)
Dann2

Pulverulescent - 31-1-2012 at 16:23

Quote:

Hmmm, have you tried adjusting the pH with the electrodes out of the cell and the electrolyte at RT?

I had just assumed you were talking about a simple chlorate-cell . . .

P

Vikascoder - 6-2-2012 at 03:39

I have made my electrode by dissolving PVC and adding MnO2 it also works pretty well

Pulverulescent - 6-2-2012 at 03:43

For what? (

)

P

Vikascoder - 7-2-2012 at 08:11

It works very well for chlorate if ph is correct but little slow for perchlorate overall it is perfect for me because lead oxide is very toxic so why to deal with it if you have an alternative

dann2 - 10-2-2012 at 13:10

@Vikascoder

How long has the Anode worked in a Perchlorate cell.
What size is the Anode.
What current do you drive into it.
Have you a camera that you know how to operate or do you have any friends with cameras that know how to operate them.

Attached is some more blow by blow by blow by blow stuff from running my LD Anode.
It is starting to show it's age at the bottom by crumbling away. I thought it would last much longer.
The messing around with the Chloride/HCl acid did not help I guess. I often wonder how Platinum would hold up in a Perchlorate cell under similar conditions.

Dann2

Attachment: ld_130.zip (193kB)
This file has been downloaded 841 times

quicksilver - 12-2-2012 at 09:46

Quote: Originally posted by Griffin

Hello,

Sorry if this is a stupid question. Are there companies that manufacture PbO2 anodes?

Many thanks

This has only been MY experience....
If you do a search, you'll find a few. They are seriously expensive. One company is in Ireland & they mfg a professional quality set. There was a company in China that had them but someone I know gambled & was very disappointed with it (it appeared homemade and was simply not worth the money in terms of it's performance or quality).

The only seriously real method is to join a "business to business" contact site (and actually HAVE a business license) & go in with someone or several more people and buy some. Buying as an individual is like buy chemicals from United Nuclear: it's not a very good deal....

dann2 - 2-4-2012 at 15:39

Hello,

Been runnin me ould Anode for close to 6 months now. It's getting rather delapidated looking but still going strong (at a much reduced surface area and current).

Added some more details to the end of this page:
http://www.oxidizing.110mb.com/chlorate/leaddiox/mmold.html

I obtained some very nice looking Sodium Perchlorate crystals on run 8 when the cell cooled down. I got similar shards on previous cell runs too.

Dann2

dann2 - 20-4-2012 at 16:55

Anode has reached the end of it's life.
Added some more to the file.

http://oxidizing.110mb.com/chlorate/leaddiox/mmold.html

Going to wake..........

BLESSED BE THE DIAMOND SHAMROCK PATENTS AND ALL THEIR WORKS!!!!!!!!!!!

Swede - 29-5-2012 at 05:29

Hi dann2, I finally caught up with your research. You've done some excellent work. I wanted to thank you for adding so much to the body of knowledge.

I find it very interesting that your LD anode exhibited nearly identical edge warts to mine, and that the failure mode was also nearly identical... the warts fell off where the LD was plated over bare edge Ti, no MMO.

The conclusions that I took from that page you posted was that additions of acid seemed pointless, and that HCl may actually be harmful. Chlorides = erosion? So the optimum bath for LD would consist of chlorates with minimal chloride. The notion of taking a 100% chloride solution to perchlorate via LD seems to be a pipe dream.

One other thought - thick LD coatings may actually be LESS desirable than thin. The anode seemed to self-destruct in chunks, with the thicker sections simply being shed in their entirety. Perhaps a thin LD coating will have less internal stresses, and would last longer.

Once a LD plating bath is set up, maybe the way to go would be to plate multiple anodes at a time (or sequentially) with a lighter coat, and when the smoke clears, the user would have half a dozen (or more) LD anodes.

dann2 - 30-5-2012 at 14:29

Hello Swede,

Accounts of making and using homemade LD Anodes for making Perchlorates (and Chlorates ) are not too plentiful.

Accounts of using LD Anodes, made by companies (professionally made Anodes) are practically non existent. The only account I know of is on APF with only some very sketchy details + no pictures that you can actually see anything useful in. So I wonder do those professionally (Chinese) made Anodes last for months in a cell?

When running my last LD Anode, I decided to spent quite a bit of time (perhaps too much) running Sodium Perchlorate cells with only small amounts of Chlorate in them as I wanted to get some knowledge of how the Anode performed in this region. This region is interesting from an Amateurs point of view as it is really a Perchlorate purification process that circumvents a re-crystallizing step. This way gives very very low CE.
If large amounts of Perchlorate are the target, then a higher CE route would be much better by keeping cells at a high Chlorate concentration (and a very high Perchlorate concentration) and taking solid Sodium Perchlorate from the cell. If I had run the MMO substrate Anode at a high Chlorate concentration a total of approx. 33KG of Perchlorate (from Chlorate) would have been produced over
the lifetime of the Anode. This particular MMO substrate Anode give very low CE even when Chlorate concentration was high. I blamed having Red Lead in the plating tank though that’s only a guess.

Making K Perchlorate directly from K Chlorate is interesting is it avoids the Na contamination. Your own account is the only one that I know of.

As you stated when you have gone to the trouble of setting up an LD plating rig it would be wise to make a number of Anodes. But then again you have to ask yourself just how much Perchlorate do you want/need.

There is still much to be learned. I wonder how the original poster of the LD on Titanium Anode managed to get such a smooth, well defined coating of LD (picture below). I think perhaps surfactant may help.

I have bailed out of the Anode scene for a while.

Dann2

I finally make a working PbO2 anode!!!

plante1999 - 31-5-2012 at 03:55

I made a working PbO2 anode! To make it I took about 13g of lead II oxide and some ammonium nitrate (The lead oxide was in excess) And added about 40ml of water and boiled the solution to make lead nitrate and ammonia. Then I filtered in 3 coffee filter and I got a clear-yellowish sol., I tested for lead by pouring some of the sol. in sodium sulphate, the test was positive.

2NH4NO3 + PbO -) H2O + Pb(NO3)2 + 2NH3

Then I took a clean mmo mesh of 1inch by 4 and a similar titanium cathode and added them in the lead nitrate sol. (mmo mesh as the anode). I electrolysed it with 3.3V dc (1 inch by 1 inch surface area each) for an hour, There was a lot of spongy lead at the cathode but then I attempted to clean the anode(The plating on the anode was really black, much more than the gray mmo coating.) with conc. HCl but I destroyed about 3/8 inch by 1/4 of the plating making insoluble lead chloride and chlorine gas... Then I attempted to repair my fault by running the anode again in the lead nitrate bath but only a very thin layer formed and the electrolyte was not conductive anymore. Then I run it at 3.5V in conc. NaCl sol. for 2 hour, there was some lead oxide in the solution and the destroyed plating which I repaired was destroyed again (I suppose the plating was too thin). I poured some clean electrolyte and cleaned the cell/electrodes and I tested it again for 10 hour, there was not lead oxide precipitate and the very black coating was still there, success! Now I'm testing its durability by electrolising it at 6V 9 amp for 10hour, if the anode is still intact it will prove that the coating is very good, and that you don't need fancy salt to make lead dioxide anode. only lead nitrate and mmo mesh and you could make lead dioxide anode.

dann2 - 31-5-2012 at 05:53

I love the idea of making Lead Nitrate from Lead Oxide (Litharge) and Ammonium Nitrate!

Would boiling Lead Dioxide (from an old car battery) and Ammonium Nitrate convert the Dioxide to Lead Nitrate if you were to boil for long enough I wonder.
Lead Dioxide is insoluble but if you boiled for long enough (simmer for a few days perhaps) the Lead might eventually all leach out with Lead Nitrate becoming the only thing left in solution.
Perhaps adding some Hydrogen Peroxide might help. I do know that Hydrogen Peroxide + Nitric acid will dissolve (react) with Lead Dioixide.

Dann2

plante1999 - 31-5-2012 at 08:14

Quote: Originally posted by dann2

I love the idea of making Lead Nitrate from Lead Oxide (Litharge) and Ammonium Nitrate!

Would boiling Lead Dioxide (from an old car battery) and Ammonium Nitrate convert the Dioxide to Lead Nitrate if you were to boil for long enough I wonder.
Lead Dioxide is insoluble but if you boiled for long enough (simmer for a few days perhaps) the Lead might eventually all leach out with Lead Nitrate becoming the only thing left in solution.
Perhaps adding some Hydrogen Peroxide might help. I do know that Hydrogen Peroxide + Nitric acid will dissolve (react) with Lead Dioixide.

Dann2

In fact my PbO was from calcined car battery PbO2, heated to 400 degree C PbO2 will decompose prety fast to PbO, I recommend to do this in a steel container. It was prety easy to make. My anode plating still look nice and does not passivate. I will run it from chloride to perchlorate. I will test with methylene blue after.

[Edited on 31-5-2012 by plante1999]

Swede - 14-6-2012 at 09:56

@dann2 - I've used surfactants, and I think they may help. I still have that LD anode I made long ago, and except for the edge nodules shedding, it still looks as good as the day I made it. But I have not subjected it to the intense testing you did to your own. I really need to push it a bit to see if the process does in fact make a durable LD over MMO anode.

In the picture you posted, if I were to guess, the substrate has a pattern of holes drilled in it. See how the LD coating has those regular dimples? When I plated my mesh, I was hoping to close the mesh holes, but that proved overly optimistic. With smaller holes, the lead dioxide would fill the holes and mechanically join both sides. Passivation of the substrate may be inevitable, but if slow enough, there may be enough contact between substrate and coating to allow the anode to last a very long time.

plante, I'm glad you are seeing some success. The big question (as always) is the durability of the anode when producing perchlorate. Any trials yet?

dann2 - 14-6-2012 at 15:53

Hello Swede,

Yes, the dimples are where the holes were in the Ti.
Its a fairly thin piece of Ti that was used.

The original post for the Anode is here:
http://www.sciencemadness.org/talk/viewthread.php?tid=1425#p...

With a description thus: (I think I got this by U2U)

(In relation to the Anode)
The process that I finally settled upon is a bit laborious but I have had pretty consistent results:
I used Ti sheet of about 1mm thickness because that is what I had at the time. A little thicker would probably be better.
The first step involves drilling the solid sheet full of small holes. I used a piece of perforated stainless as a drilling guide/pattern. The holes then need to be de-burred or slightly countersunk to get rid of the ragged edges left by the drilling step; I just used a larger diameter drill bit to do this.
The substrate should then be sandblasted, (to help the PbO2 adhere to it. The holes are needed for the same reason) degreased with dish-washing soap, thoroughly rinsed in clean water and dried.
Next, a semiconducting coat of Sb doped SnO2 was applied by painting on a solution of SnCl4 + SbCl3 in water + Butanol, drying, and then heating to 500°C or so in an oxidizing atmosphere i.e. air. This step was repeated five to ten times to give a suitable coating thickness.
Then a thin (about 0.1mm) layer of Alpha PbO2 was plated onto the substrate from an alkaline lead tartrate bath.
The final coat of beta PbO2 was then plated over top of this from a lead nitrate bath. This layer was about 2mm thick.

The Anode performed well in a perchlorate cell.
The Anode above was only used for two batches of perchlorate, starting from NaClO3, which means that it has seen about 200 hours of use at a current of 35-40 A. It still looks pretty much exactly the same. I have made other Anodes (using the same process) that I've used in Chlorate cells for hundreds of hours with no visible signs of wear.
The Alpha PbO2 layer was added in order to improve adhesion + uniformity of the final beta PbO2 layer. See US5683567 for a description of a very similar anode. I used to always try and cut corners but after accumulating a whole lot of hazardous waste from failed attempts I've come to realize that it is easier to do it properly, even if it is more work.
I chose the SnO2/Sb2O3 system because it is easy to apply and the raw materials are easy to come by and above all cheap. SnO2 also has a higher Oxygen overvoltage than PbO2 which supposedly means that any exposed SnO2 will not interfere with the Anodic formation of Perchlorate.
____________________________________________________-

In relation to passivation of the substrate it may not be that serious after all.
I guy on a different forum has simply bolted a piece of Ti to a platinum anode and put the anode + connection into a cell and it workes OK. I have done the same thing with MMO and a Titanium runner (connection) and it seems to work OK. It's as if the current is able to 'jump' a small gap + the Ti Oxide once the connection is under the surface of the electrolyte. The surface of the connection where it matters (beside the Anode material proper) seems to act almost like a cathode and the surface layer of Ti Oxide which is usually a good electrical insulator becomes conductive (by the hydrogen released in the vincity) just like when Ti is used as a cathode.
It's described in a paper posted here somewhere or other. The released hydrogen dopes the normally insluating Ti Oxide and it becomes conductive.
Some of the Anode pictures that I posted show pieces of LD literally hanging off the substrate yet they seem to go on working (passing current into the electrolyte) until they fall off completely.

Dann2

[Edited on 15-6-2012 by dann2]

Swede - 15-6-2012 at 06:45

I know we've flogged this to death in various threads. We repeat ourselves over the years and go in circles, but it's hard not to.

I think the answer (for garage PbO2) will ultimately be a simple one, and I suspect it'll involve unique anode geometries, moreso than polymers or other compounds designed to give the correct PbO2 both structural integrity AND continuous conductivity with a suitable substrate. That is where I was going with the holes.

Perhaps a Ti substrate can be constructed such that the PbO2 is not hanging on for dear life, but is instead compacted into chambers or holes. Like a honeycomb... the Ti is the wax, and the PbO2 is the honey. Simplistic, but you get the idea. Of course, when you plate something like that, the fastest buildup is in areas where you wouldn't ultimately want it, rather than the voids.

Maybe mechanical intervention during the plate process? A scraper periodically over the horizontal surface... buildup is allowed only/primarily in the voids.

Of course, correct prep of the substrate will always be a factor, and if not done, it'll simply shed or passivate so badly that no current will flow.

Swede - 15-6-2012 at 06:50

Follow up thought - start with a sheet of Ti, 6mm thick or so. Spray the sheet with some sort of resist... a lacquer of some sort, so as to prevent electrical contact with the lead salts bath. Drill a pattern of holes in the sheet to form the honeycomb chambers. Chemically prep/etch the chambers so as to receive the plating. Plate away... the voids fill with PbO2, the faces do not, and you end up with an anode that is mechanically sound, at a minimum. If the Ti / PbO2 junction does not passivate, then it might be practical.

dann2 - 15-6-2012 at 09:58

It is difficult to get PbO2 to plate into deep (ish) holes or into (inside) corners. The outside rim of the hole will plate first and plug the hole IMO.

I think myself the garage PbO2 Anode HAS arrived. Its PbO2 on MMO!!!
The original poster of the Ti substrate anode (pictured above) said that the anode has done many many hours. It may not look so good after many months?
I am not knocking his Anode saying this. These things only have a certain life time.
Perhaps an improvement can be made by incorporating a fine reinforcing mesh, like the guys doing the massive anode, wrapped around the MMO mesh. Hashashan used stuff for domestic pot cleaning. PVC I presume it was made from.

BTW the anodes I made last time had very low CE for some reason or other. I am not too sure why.

Dann2

[Edited on 15-6-2012 by dann2]

Swede - 26-6-2012 at 08:43

It is interesting... quite a few PbO2 anodes being offered from China on Alibaba and similar sites look very similar to those we have produced in our labs.

These vendors also discuss some of the technical aspects of PbO2, such as recommended current density, conductivity, and application notes.

PbO2 anodes on Alibaba

Check out some of the pictures... edge warts and all. I wonder if these commercial anodes are truly superior to those we have made, or if they are simply used as a replaceable commodity with a fixed life?

In retrospect, the challenging part of plating PbO2 is in the setup. As I believe I mentioned earlier, once a respectable plating system is set up, the way to go would be to plate a half dozen anodes in succession, obviously keeping track of the bath constituents. A plating bath of respectable volume would be more expensive and troublesome, but would be chemically more stable, and capable of generating multiple anodes over the course of a plating session.

[Edited on 26-6-2012 by Swede]

dann2 - 26-6-2012 at 12:29

Hello Swede,

They don't seem too warty to me, but then again the photos are not up real close.
This one (its one with six connections going to the same anode or is it two anodes on top of one another?)
http://baojichangli.en.alibaba.com/productshowimg/494839933-...

seem to have pieces of thread coming out of it. I wonder what that is. fIber reinforcing perhaps?

Regarding tank size, you can work with quite modest tank volumes and use a pump to keep pumping in neutral Lead Nitrate. A simply peristaltic pump is OK.
Tank size I used last time was about 1 liters and one liter in neutral tank with the solution and could go on for ever IMO. Just keep adding Lead Carbonate and some Copper carbonate if blue colour gets weak.

I will look up an article on Graphite substrate anodes. I think they lasted an average of X months (5mm thick PbO2 coat).

edit:

Looking at some articles here and here

The first link states:
The anodes gave satisfactory service for 24 months
with 50% of the anodes still in good condition. A current
efficiency of 70-80% was obtained while depletin

See table 4 in the second link.

To make a long story short LD anode don't last for ever. Though if I made some with Graphite substrates and they lasted that long I would be happy. But you might always got a bad one.

Thats the advantage with Ti. Even if you get a 'bad' one it will run and run.

The guys in china probable have access to custom pieces of Ti coated with MMO all over. They are not cutting MMO and having problems with the 'ends' not being coated with MMO. They even seem to have end edges of some of the anodes reinforced with flat Ti strips or some such.

[Edited on 27-6-2012 by dann2]

Anode

tomasbrod - 10-7-2012 at 03:08

I have a problem with plating PbO2 on graphite substrate. I started with lead copper vinegar sodium bicarbonate lathern batteries 500uF capacitor diode and 4-6V AC power supply. I made sodium acetate solution put lead and copper strips in it and connected lead to positive and copper to negative 4-6V 300mA. Gray precipitate of Pb(OH)2 filtered after a day. Repeated until half of lead strip eroded. Some lead plated on copper so my Pb(OH)2 was contaminated with lead(0). Then i replaced remainder of lead strip with copper wire. Again repeated until anode eroded out. I neutralised Pb hydroxide with vhite vinegar and it bubbled. Light blue copper hydroxide not bubled when neutralising, but dissolved after a while. Both acetates crystalised on sun. Lead acetate - nice cristals. Copper acetate - samll crystals with white and brown contamination. I put coiled copper wire in a beaker. Then dissolved 1:3 by volume of both acetates in the beaker. I opened a lathern battery and get graphite electrode 7mm in diameter. I sanded the electrode. I attached a copper wire on top and put in centre of the beaker. Hooked wires and turn on power. Set current to 15mA. Added drop of dish soap(surphacant). A bit plated but then bubbles started forming on anode. No bubbles on cathode instead nice small lead crystals formed. Is there any way to prevent the bubbles?

hissingnoise - 10-7-2012 at 06:19

Preparation of graphite-substrate lead dioxide anodes, improved method!

Swede - 10-7-2012 at 11:35

This is weird... I was browsing yet again for PbO2/perchlorate info and ran into a paper published in an Iraqi science journal. As I read it, I'm thinking "I've read this before. I'm positive."

I found the article it in the "Diyala Journal of Engineering Sciences", vol 2, No. 1, June 09. Does the following ring a bell with anybody? I believe the real author to be a member here...

Here is the text, supposedly by one Ahmed D. Wiheeb. The article (a PDF) can be found Here.

From "Mr. Wahib's" paper:

Quote:

DSA stands for Dimensionally Stable Anode. This is the common term used to refer to anodes consisting of a layer of noble metal oxides (usually RuO2 and TiO2) coated onto a substrate, usually titanium. This type of anode is finding increased use in industrial cells because of its comparatively low cost when compared to platinum and its resistance to corrosion. The chemicals required to manufacture these anodes are expensive and difficult to handle. However, if the chemicals can be obtained and suitable equipment is available, the procedure to make the anode seems fairly straightforward and may be an option

The exact same text, as well as the bulk of the guy's "paper", can be found here.

Quote:

DSA: DSA stands for Dimensionally Stable Anode. This is the common term used torefer to anodes consisting of a layer of noble metal oxides (usually RuO 2 and TiO 2 )coated onto a substrate, usually titanium. This type of anode is finding increased use inindustrial cells because of its comparatively low cost when compared to platinum and itsresistance to corrosion. The chemicals required to manufacture these anodes areexpensive and difficult to handle. However, if the chemicals can be obtained and suitableequipment is available, the procedure to make the anode seems fairly straightforward andmay be an option. For the preparation of these, the reader is referenced to the literature.Again, I'd be most interested in anyone’s experiences with this type of anode

Again, didn't someone here write this stuff? Dann2, is this your text? The guy ripped someone off with a blatant cut and paste job for the "theory" section of his article. Wow...

Swede - 10-7-2012 at 12:06

Follow up: In an attempt to get back on topic, I did find an excellent article that explained one question that had been bothering me for quite some time.

In my perchlorate cells, both platinum and lead dioxide, I reported here the distinct odor of ozone (O3) being generated at the anode, and thought perhaps that it might have been part of the reaction mechanism. It's not. It CAN and does form, but only with the incorrect setup and operation of a cell.

Quote, from the excellent paper...

Quote:

Only oxygen and perchlorate are formed at the anode during electrolysis under the conditions used in this investigation [5]... The formation of ozone can only take place under extreme electrolysis conditions like high current density and low chlorate concentration.

Thus, high (excess) current densities, and/or low chlorate concentration, can result in O3 generation. Since I noticed ozone immediately upon power up, I can only surmise that my current density was too high.

This can possibly be a tool... if the distinct odor of ozone is emanating from the vent port, dial the current back a bit.

The paper is a good one. I am going to spend a bit of time and try to absorb some of the theory.

dann2 - 10-7-2012 at 14:37

Hello Folks,

@ tomasbrod
My advice regarding Lead Dioxide anodes is to STAY CLEAR of graphite as a substrate. You are going to need a perfectly formed coating of Lead Dioxide and a fairly thick coat. You will not achieve this perfect coating in the set up that you have no matter how hard you try.
If you cannot get DSA try to coat some Titanium with Tin Oxide and start from there. If you cannot obtain Ti then start with a massive anode with fiber reinforcing in it (grow it on Iron or a flat piece of Graphite.
The Graphite substrate is going to let you down, waste your time and your chemicals.

The text you are referring to Swede sounds alot like stuff I wrote. I wonder did the Iraq guy do all those experiments with a graphite substrate Anode? It would take months and months. He certainly did not do it with one anode IMO.

Anyhow in the stuff that you copied and pasted he is actually claiming that :
"This type of anode [DSA] is finding increased use in industrial cells because of its comparatively low cost when co mpared to platinum and its resistance to corrosion." [for perchlorate production].
This is nonsense. It is not and will not (in any sensible fashion) make Perk.
He also states that Magnetite has been used in industry for Perchlorate production which is more nonsense.
None of the references he gives in relation to DSA and Magnetite state that they can be used for Perchlorate production. He is mixing up Chlorate and Perchlorte production.
(The myths continue)

Perhaps MMO made from Platinum Oxide (as suggested by JP Smith) will make Perchlorate. I don't know myself. I have never seen the stuff or don't know if it is made commercially.
MMO made from Platinum Oxide should make Perchlorate because its Platinum Oxide that actually makes Perchlorate when using a Pt anode. (If you read an article from Johnston Mattey). A very thin layer of Pt oxide forms on the Anode.
At the end of the day you are back to a Pt anode.

Dann2

hyfalcon - 17-10-2012 at 04:28

I don't know if anyone is still interested in this topic or not but I just found an interesting patent.

Attachment: insoluble anode of porous lead dioxide for electrosynthesis-preparation and characterization.pdf (869kB)
This file has been downloaded 1135 times

tomasbrod - 21-10-2012 at 10:16

Quote: Originally posted by dann2

@ tomasbrod
You are going to need a perfectly formed coating of Lead Dioxide and a fairly thick coat. You will not achieve this perfect coating in the set up that you have no matter how hard you try.
If you cannot get DSA try to coat some Titanium with Tin Oxide and start from there.

Yes, you hav had true.
I let plating run for more than month on current as low as 10mA and got about 1.5mm coating. I mounted small phone vibrator (20x5x5mm) and set it on timer to vibrate every half minute. Vibrations had not stoped bubbles forming and after three weeks vibrator felt from anode because strong acetic acid vapours. I was lazy to set up NaCl electrolysis until now. Anode lasted two days on 0.3A and then cracked on two sides from top to bottom. Now i have even more PbO2 powder and clean graphite rod. Now i have again some free time so I dissolved polistirene in turpentine. To paste I added MnO2 powder from batteries. I will put the paste in sharpe, let it dry and try to plate PbO2 ower it. If it fails I will try aluminium tin Zn and iron. My method of preparation lead acetate is very fast and cheep on chemicals.

Vikascoder - 31-12-2012 at 21:25

There are lots of questions arising in my mind about Pb02 anodes
1 can battery anodes that is lead coated with lead dioxide be used directly in chlorate or perchlorate cell if no then why it can't be used
2 what is the best way of coating titanium with Pb02 so that it works for maximum time

IrC - 2-1-2013 at 18:21

http://www.freepatentsonline.com/6248221.html

Since lead sheet is really easy to roll into cylinders this patent might be something to consider, as far as the cell geometry is concerned.

Attachment: US6248221.pdf (264kB)
This file has been downloaded 794 times

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