Sciencemadness Discussion Board

More on PbO2 electrodes

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garage chemist - 30-5-2007 at 10:04

I found a supplier for RuCl3, it costs 159€ per gram which is ridiculous. Also, 5g would be the minimum amount to buy.
I'll look for Ru- free alternatives. I probably will make my own recipe using Pd, of which I already have some.

I know that MMO/DSA anodes dont make perchlorates.
Platinum is the optimal anode for chlorate ---> perchlorate, I have much experience with this (essentially zero platinum erosion when the chlorate is pure and dichromate is used according to my experiments).
What is needed is a good non-eroding anode for chloride ----> chlorate.

dann2 - 30-5-2007 at 14:59

Quote:
Originally posted by garage chemist
I found a supplier for RuCl3, it costs 159€ per gram which is ridiculous. Also, 5g would be the minimum amount to buy.
I'll look for Ru- free alternatives. I probably will make my own recipe using Pd, of which I already have some.

I know that MMO/DSA anodes dont make perchlorates.
Platinum is the optimal anode for chlorate ---> perchlorate, I have much experience with this (essentially zero platinum erosion when the chlorate is pure and dichromate is used according to my experiments).
What is needed is a good non-eroding anode for chloride ----> chlorate.


Hello,

Have you ever tested your Perchlorate cell when for the presence of Chloride using Silver Nitrate. It would be interesting to see if any Chloride shows up that is visually detectable using the Ag Nitrate.
According to Schumacher, The Perchlorates (book) some Chloride is produced in a Perchlorate cell from dissociation of Perchlorate (or is it reduction at the cathode, I cannot remember).
If, say, all or most Perchlorate cells run with one or two percent Chloride in them due to the above there is little point in trying to recrystallize Chlorate so that you get to the 100.000% Chlorate, 0.000% Chloride point.
Perhaps the amounts of Chloride generated in a Perchlorate cell are tiny when you use Chromate to stop reduction at the Cathode.

Regarding MMO for perchlorate I have run an mmo cell with Chlorate only (there was a few % Chloride in it too) for about three weeks, one amp into a half liter cell. Current density about 130mA per cm squared. No Perchlorate formed.
In fact I was convinced the Chloride level increased somewhat at the start of the cell run. Ag Nitrate as a visual test was used for the Chloride. NaF was used in cell. The MMO was an anti corrosion wire anode.
Ir + Ta Oxides on Ti rod AFAIK.
According to a patent I have read Lithium seems to form into the Perchlorate very easily (easier than the other more usual metals). Perhaps it may be possible to get Li Perchlorate to form at MMO.
I guess there is only one way to find out.


Cheers,
DANN2

jpsmith123 - 30-5-2007 at 16:27

It's confusing to me since a few people have in the past claimed to make perchlorate with pool chlorinator anodes.

I suppose it probably depends on the exact MMO composition and process details. From what I've read, PdO would be better than RuO2, for example.

Right now I'm having a discussion with someone on rec.pyrotechnics about it. He's already made chlorate, and is now attempting to make perchlorate. I don't think he knows the composition of his MMO coating, however.

Some interesting patents

Rosco Bodine - 30-5-2007 at 19:27

These few should probably be added to the collection
of patents having possible usefulness with regards to perchlorate anodes .

US4422917 Describes a substoichiometric titanium dioxide
which is formed by high firing the normal stoichiometric material in the presence of a reducing material admixed
with the clay , or firing in a reducing atmosphere . The resulting vitrified ceramic has extreme corrosion resistance
and electrical conductivity similar to graphite , and high
oxygen and hydrogen overvoltages which allow for its use as either anode or cathode or both .
US5126218 gives more information on the ceramic material
which is / was commercially produced and called Ebonex
by Lambertville ? More information on this I have not searched , but here is a page link for a manufacturer

http://www.atraverda.com/Ebonex_tech.htm

There is a hundred page book on the material by the inventor available from RSC publications

http://www.rsc.org/publishing/ebooks/2001/9780854049844.asp

US2994649 Describes a method for plating beta PbO2 on a stainless steel substrate , maintaining current efficiency by
a concurrent addition of hydrogen peroxide to the nitrate plating bath . This might have usefulness for the production
of massive PbO2 anodes on a cheaper more readily available substrate from which the finished part may be stripped .

US3033908 Appears to be the original patent concerning
alpha PbO2 , and describes a bath which is a combination of lead acetate with sodium nitrate , operated at room temperature and a slightly acid pH . This patent is of particular interest to me anyway , as it produces the alpha
PbO2 under conditions which are close enough to those for
the nitrate bath used for deposition of the beta PbO2 , that
it seems possible to devise a plating mixture which could concurrently precipitate both alpha and beta PbO2 in a blended structure which would be inherently stable by
virtue of being internally stress relieved at a microstructural level . Also interesting is that this bath for alpha PbO2 produces a deposit which is not so strongly adherent to the substrate as is the deposit from the alkaline tartarate bath
of US4064035 , and this could be an advantage in the easier
separation of a massive anode from a substrate , where the
alpha PbO2 is used as a priming layer . Also , it would seem
that because this alpha PbO2 bath is acidic , that it may allow for use of a graphite substrate .


[Edited on 24-6-2007 by Rosco Bodine]

Attachment: US2994649 _LEAD_DIOXIDE on stainless steel substrate.pdf (112kB)
This file has been downloaded 824 times


garage chemist - 30-5-2007 at 21:20

My Perchlorate cell does not produce any chloride, I've tested it with AgNO3 before and after the run.
I use dichromate and commercial 99% NaClO3.
Once I ran it without dichromate, and then it definately produced some chloride. The platinum anode was also visibly attacked, which did never happen before when I used dichromate.
So it is probably cathodic reduction which forms chloride, and this is prevented by dichromate addition.

Can dichromate be used with MMO anodes in a chlorate cell? I'm unsure about that.

Does anyone have patents concerning manufacture of chlorine- resistant MMO anodes using PdO/PdO2 and TiO2 as the conducting oxide? If I cant find any, I'll use one of the Ru based recipes (butanol, butyl titanate) and substitute RuCl3 by H2PdCl4.

Who knows what butyl titanate is supposed to be? Can it be made from TiCl4 and butanol?

[Edited on 31-5-2007 by garage chemist]

Hmmm...aluminum is a listed "valve metal" !

Rosco Bodine - 31-5-2007 at 00:24

Maybe this has been mentioned before , I don't think so .

If the combined tin and antimony oxides which are baked onto a "valve metal" as a semiconducting "anodization" , and upon which can be plated PbO2 ......then aluminum
could certainly be useful as a cheap and easily removable
substrate for a massive PbO2 anode .

The idea would be to first produce the aluminum sheet with
the combined oxides and place it in a plexiglass baffle ,
a sort of picture frame which would blank off the backside
and edges from the plating on of the PbO2 . So the PbO2
could be built up into a 3/8" - 1/2" thick layer on the front side only . The completed anode could be separated from
the substrate by simply scratching through the oxides layer
on the unplated backside , using a rotary stone or file to
expose naked aluminum . Paint on some HgCl2 in dilute HCl
and immerse the whole assembly in dilute HCl or any other
dilute acid and the aluminum substrate would be etched away completely , leaving the massive PbO2 in one piece ,
no chance of breakage from otherwise having to pry it away
from a metal substrate . And no expensive titanium required .

Along the same line of thinking , a massive PbO2 anode
could similarly be plated onto one side only of a thin graphite
sheet , and then not even attempted to be pryed from
the thin graphite substrate .....but put into use in the cell
where the corrosive action of the cell itself erodes away the
graphite substrate , leaving the massive PbO2 anode to
continue working just fine ( hopefully ) after having been
relieved of its graphite .

alancj - 31-5-2007 at 02:42

Does strong alkali attack PbO2? Considering that some plating baths are alkaline, I'm thinking it should be inert to it. If it is, then a solution of sodium hydroxide would easily dissolve the aluminum right off.

-Alan

Rosco Bodine - 31-5-2007 at 04:02

IIRC there is better resistance of PbO2 to acid than to alkali , and the etching away of amalgamated aluminum
is a whole lot more rapid in dilute HCl than in alkali .

Another possibility for using aluminum as a substrate
is to plate onto it 20 microns or so of nickel or cobalt ,
and then plate on the lead dioxide . Of course this
nickel plated aluminum would never hold up in a chlorate cell , but it would hold up in the lead dioxide plating process . And then similarly , by scratching through the
thin plating , and loosing upon the aluminum the HgCl2 ,
the same disappearing of the aluminum would occur .

But really , the more I think about the graphite idea ,
the more it seems like the simplest idea to just let the
cell itself eat away the graphite . The substrate of course
is expendable for either of these approaches ....it is a one
use substrate , which is the only down side that I can see about this idea .

Pt or MMO Pool Chlorinator Anode

dann2 - 31-5-2007 at 04:15

Quote:
Originally posted by jpsmith123
It's confusing to me since a few people have in the past claimed to make perchlorate with pool chlorinator anodes.

I suppose it probably depends on the exact MMO composition and process details. From what I've read, PdO would be better than RuO2, for example.

Right now I'm having a discussion with someone on rec.pyrotechnics about it. He's already made chlorate, and is now attempting to make perchlorate. I don't think he knows the composition of his MMO coating, however.


I think some of the Pool chlorination anodes are Pt based. They have a coating of Pt on them (not the shiney variety but the black variety). They are described as bipolar. Think that means you can put an ac to them. It also means you can reverse the DC (if using dc) to clean them.

There was a guy here using a 'sachlor' anode to make Perchlorate. A fellow contributor said this anode was a Pt based anode. The user thought/said it was MMO.

Thread can be got from here:
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

EDIT:
Sorry JP it was yourself that uploaded the pool anode image:)

Cheers,

Dann2

[Edited on 31-5-2007 by dann2]

dann2 - 31-5-2007 at 04:33

Quote:
Originally posted by Rosco Bodine
Maybe this has been mentioned before , I don't think so .



Along the same line of thinking , a massive PbO2 anode
could similarly be plated onto one side only of a thin graphite
sheet , and then not even attempted to be pryed from
the thin graphite substrate .....but put into use in the cell
where the corrosive action of the cell itself erodes away the
graphite substrate , leaving the massive PbO2 anode to
continue working just fine ( hopefully ) after having been
relieved of its graphite .


The whole problem (as I see it) with the massive anodes is that you are going to need very good plating conditions. Well controlled temp., concentrations, etc. It is difficult to get one big piece of Lead Dioxide to stay together. It is also VERY fragile. Let it fall and it's goodnight anode.
The substrate (if we can get one) is essential reinforcing.

Dann2

hashashan - 31-5-2007 at 04:44

i have dropped my anode (very thick anode on fabric) several times from about 1.5 meters and it didnt crack. So this PbO2 is not so fragile as one might think. As soon as it gets above 3mm thick its quite strong/

jpsmith123 - 31-5-2007 at 05:45

Garage Chemist, several of Beer's patents have examples that use PdO (from PdCl2). I think the main reason PdO is not used commercially is because Ru and Ir are significantly cheaper.

As far as I can tell, the processes are basically the same regardless of which PGM oxide is used; IOW, the PdO/TiO2 coating can be put on electrolytically or by thermodecomposable salt solution.

I think I posted the "recipe" for electrodeposition of a RuO2/TiO2 coating somewhere here before. I can post it again if you can't find it.

BTW there are a few Japanese patents that exclusively use PdO. Supposedly it has a very high oxygen evolution overpotential, thus I think it would be a good candidate to make perchlorate.

garage chemist - 31-5-2007 at 07:04

I just looked for Beer's patents, and found one where Pd is used:
US3711385
But no TiO2 is used here, so the electrode obtained in that way most likely wont be as resistant as one with TiO2 and PGM oxide.

I keep looking for a patent which describes a TiO2/PdO anode.
Pd seems to be much cheaper than Ru, but the prices of all those metals have changed very much over the years, so what once was cheap can today be very expensive. Pd is currently much cheaper than Pt.

EDIT: Another one which uses Pd, but again without TiO2: US4052271

Maybe I'll try one of those when I get my titanium, and see how well they hold up. Maybe it is not necessary to purchase TiCl4 in order to make a functional DSA coating.
If it doesnt hold up, Ru and TiCl4 will probably have to be purchased, with Ru from a supplier who has decent prices.

[Edited on 31-5-2007 by garage chemist]

jpsmith123 - 31-5-2007 at 10:08

There used to be someone selling RuCl3 on ebay, although I don't see it there anymore. I think PdCl2 is easier to find and cheaper because Pd has more industrial/commercial uses.

Here's 5 grams of RuCl3 for sale for $72.60:
https://new.fishersci.com/wps/portal/PRODUCTDETAIL?LBCID=856...

With regard to a PdO/TiO2 coating, I will have to look for it. In the mean time, in Beer's patent# 3632498, on page 4, there is a table where he qualitatively compares the various "coprecipitated oxides", and Pd/Ti is among the contestants.

Rosco Bodine - 31-5-2007 at 11:24

Quote:
Originally posted by dann2
The whole problem (as I see it) with the massive anodes is that you are going to need very good plating conditions. Well controlled temp., concentrations, etc. It is difficult to get one big piece of Lead Dioxide to stay together. It is also VERY fragile. Let it fall and it's goodnight anode.
The substrate (if we can get one) is essential reinforcing.

Dann2


I think you folks are so in love with the idea of titanium substrates and elegant semiconductor coatings that you can't see the forest for the trees . There are several different sources which indicate that the massive PbO2
anode is technically superior and much easier to make .
And in terms of technical difficulty and need for exotic materials and labor intensive high temperature lamination of doped oxides onto titanium , ......for all that work on a substrate , it is still the PbO2 which is the working surface ,
and the only real advantage gained it would seem is not
needing to silver plate for the connection when a conductive
permanent internal substrate is being used . Given the costs
of titanium and the other materials and labor ....I just don't see how the doped titanium substrate is superior except in terms of bragging rights for having the product of exotic materials and methods and a whole lot of work , which may
not even last as long as a massive PbO2 anode more easily and cheaply made .

Aside from the previously mentioned possiblility of coplating
alpha and beta PbO2 from a mixed bath , it may also be possible to add the barium dioxide component as a third component , all being blended and layered either as distinct
plys simply by stepwise variation of the plating current , or
as a continuous composite laid down by a varied intensity
waveform of direct current as may come from rectified AC .

The possibilities of using common and economical substrate materials which are temporary substrates only used in the
anode deposition process and then stripped from the massive anode which serves as the working part are obviously superior economically and technically simpler ....
if the service life of the end result is acceptable .

Bottom line is that no matter how exotic the substrate ,
even if pure platinum , the working layer of PbO2 will
separate eventually if it fractures exposing the substrate ,
whether the substrate corrodes away or not ....the anode
will fail some time after fracturing , even if it takes a considerable time after the working coating fractures .
This will hold true for the oxide treated titanium substrate ,
as the poor mans platinum substitute will fare no better
than the real thing . It will most definitely eventually fail in a similar way , worse than would a platinum substrate , though to a lesser extent even the platinum will erode .

Therefore it would seem that the very best substrate is no substrate at all . Because any substrate which isn't truly inert in the cell will eventually compromise the anode .

Attached is one patent for the massive PbO2 electrode ,
although there are many variations on the theme described in other patents . The drawings are not very good really , and they are showing a scheme where both sides of the substrate are used for making a pair of massive anodes simultaneously . This is in contrast to my idea of blocking off the backside and forming one massive anode only on the front surface of a substrate . This one side plating of a substrate , including a graphite substrate , has been described in other patents . What I am suggesting has in some forms been done already . But I don't know of any
references where various refinements have been combined
to try to optimize the massive PbO2 design .

Attachment: US2846378 Massive PbO2 Anode method.pdf (388kB)
This file has been downloaded 1248 times


12AX7 - 31-5-2007 at 14:39

How about this: take a sheet of, say, copper, apply duct tape to the narrow sides, and plate PbO2 over it. Now, peel off the tape and copper (or dissolve it in nitric). Voila, two massive anodes, pure PbO2!

Nevermind that it'll take ages to plate, but still...

Tim

dann2 - 31-5-2007 at 16:33

Quote:
Originally posted by 12AX7
How about this: take a sheet of, say, copper, apply duct tape to the narrow sides, and plate PbO2 over it. Now, peel off the tape and copper (or dissolve it in nitric). Voila, two massive anodes, pure PbO2!

Nevermind that it'll take ages to plate, but still...

Tim


I hate to be a party pooper (read: I love being a party pooper:-)) but the massive Lead Dioxide anode is not an easy thing to achive. Have you ever heard of anyone, having made a substrate anode, had it fall apart, being left behind with a quantity of usable massive anodes at the bottom of the Chlorate tank.
It is my opinin that when you have plated on your perfect (and it had better be perfect) coating of Lead Dioxide on your removable substrate, that you will be very lucky to have a usable anode left after you remove said substarte. Perhaps I have gone Ti mad.
A lot of the literature I have read (not patents) that have mentioned massive anode have always said that they were problamatic or that the yield was low. ie. expect a large failure rate when making them.
The Lead Dioxide that most amateurs will plate (at least like myself) will not be of A1 standard. When substrate is removed (intentionally as when making a massive anode or unintentionally as when a substrate anode gives up the ghost) you will be left with only small pieces of Lead Dioxide.

Perhaps I am too pessimestic.

The cloth substrate anode is really a massive anode with some reinforcing in it. The cloth (or whatever) hopefully holding the whole lot together. I would suggest of anyone is making massive anode would be to try and incorporate some sore of cloth/mesh material into the anode to help hold it together.
I once had a massive anode. It was a piece that came off the side of a ceramic substrate anode and was about 1.5cm
by 7cm by 3mm thick. Not a very big anode by any standards.
It was the only piece of Lead Dioxide that I ever got that was usable out of all the anodes that fell appart.

Most of the patents make anode making sound very very straight forward always adding some new device/process/chemical that allegedly transforms the whole process.
I noticed that the patent that Rosco put up here yesterday? (thank you) used a 300 gallon!!!!!! tank of Lead Nitrate.
They did not mention what size the anode was but a tank
that size (unless the anode was being lifted in and out of the tank with a crane) would give a very stable pH, Ion concentration and temperature during the course of the plating process.
Few are willing to invest in a two or three gallon tank per smaller anode.

Dann2
(wasp chewing)

dann2 - 31-5-2007 at 16:41

Quote:
Originally posted by hashashan
i have dropped my anode (very thick anode on fabric) several times from about 1.5 meters and it didnt crack. So this PbO2 is not so fragile as one might think. As soon as it gets above 3mm thick its quite strong/


Hello Hashashan,

Did you do this on purpose to test the ande or was it an accident?. If you did it as a test you are a much braver man than myself (and most others too I guess :D)

Dann2

Rosco Bodine - 31-5-2007 at 18:47

Industry patents have in general proven to be sources of good information for me anyway , although there are a few
exceptions ...some of which can be debunked with a little effort . Several of the PbO2 deposition method patents test the particular process for its value in producing a massive anode , since a quality strain relieved thick layer is stable as a massive anode , whereas a stressed deposit indeed will crack and crumble . It is sort of a litmus test for the stability of the plating which will then be also stable in much thinner platings on anodes which do have a substrate .....if that is the interest instead .

I don't have a problem with setting up the equipment necessary to test some of these ideas , as I already have
most of the needed materials and equipment on hand for
other uses . It is simply a matter of finding time , clearing my bench , and setting it up and running the process . I can pretty closely duplicate the controlled conditions described by the patents .

If you look at the example 3 in patent US4064035 ,
there is an example of one side of a graphite substrate being
plated with a thick layer of PbO2 . But it seems like they are using an overly thick graphite which must then be separated
with some difficulty . This is one of those points where it appears they simply used the material which they had on hand , which was not ideal ....but the focus of interest was the massive anode produced succesfully . IMO a thinner substrate plate could have functioned just as well .

Anyway , as for the complexity of the anode production setup required , unless you are doing some really thin buildups of PbO2 , then you are going to need the same equipment for making a massive anode , it simply has to run for longer time to build the added thickness . I see no difference there in the technical requirement except for the longer time for the plating run , and of course more lead salts for replenishing the bath .


@12AX7
Copper can be used as a temporary substrate for PbO2 as can aluminum , if it is first plated with nickel . Of course since copper would be more difficult to etch away , as compared with amalgamated aluminum , copper would seem to offer no advantage over say stainless steel which could be used directly without plating , in a bath containing hydrogen peroxide . Physically prying off the deposited anode would be required for the stainless steel substrate , and that is likely to be the case also for the copper . It would seem that
a concentrated enough nitric acid for etching away the copper would likely also attack the PbO2 . So copper would
seem not to be a good candidate as a substrate due to these complications , even with the use of super duper duct tape around the edges , and several hopeful alchemists chants and amulet waving ....it just doesn't seem likely:D

Aluminum however , with nickel plating is another matter .

Attached is a patent US2492206 which describes construction
of a special type of battery capable of producing high current even when operated in extremely low temperatures where conventional batteries deactivate . The patent , although
it relates to production of a primary cell , makes use of a lead dioxide anode , and some details of its preparation are pertinent to PbO2 anodes in a more general sense , including the production of perchlorate cell anodes .
For example the same plating bath could be used for our purposes , and a drawing shows the setup , which includes
a small recirculation pump and filtration arrangement perfectly applicable to our needs . An aquarium power filter
would seem perfect to fit the function of maintaining the pH
and Pb content of the plating bath . The patent also mentions the usefulness of basic lead salts for buffering the
pH , which is something I have mentioned also would be preferable to the use of lead carbonate or oxide .

@dann2
The important detail to learn from the patent US2994649 which described the usefulness of hydrogen peroxide for
control of nitrite levels which destroy the efficiency and quality of a plating bath , is not that it only works in a 300 gallon government facility plating tank ....but that it likely solves the same problem the same way in a laboratory scale plating bath . The problem of increasing levels of nitrites has a simple solution , and if that solution improves the performance of a bath enough that plating onto a stainless steel substrate becomes efficient , as well as improving the plating onto nickel and even platinum , then it is a worthwhile additive which very probably results also in a better quality of PbO2 deposit . Increased cell efficiency means less waste heat from IR loss and side reactions which
should translate to a cleaner purer and denser PbO2 deposit which is laid down at a faster rate . These are good things :D , ......not problems .

BTW , on your website there is an interesting
article , JES Vol.104, No. 7 (July 1957) page 448
Electrolytic Production of Bromates , which describes
the deposition of massive PbO2 anode material on *iron*
substrate from a *neutral* pH lead nitrate bath . It would hardly get any simpler than that , if a piece of low carbon soft steel would work as well . I am thinking cold rolled bar stock could do the trick as a substrate . or possibly even a soft cast iron , or mild steel .

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...


[Edited on 1-6-2007 by Rosco Bodine]

Attachment: US2492206 Nickel Plated Aluminum PbO2 Electrode.pdf (213kB)
This file has been downloaded 702 times


hashashan - 1-6-2007 at 06:25

Quote:
Originally posted by dann2
Quote:
Originally posted by hashashan
i have dropped my anode (very thick anode on fabric) several times from about 1.5 meters and it didnt crack. So this PbO2 is not so fragile as one might think. As soon as it gets above 3mm thick its quite strong/


Hello Hashashan,

Did you do this on purpose to test the ande or was it an accident?. If you did it as a test you are a much braver man than myself (and most others too I guess :D)


It was an accident ... however it did occur several times.

And i see you are offering to plate PbO2 on metals and then ermove the metals .. I CANT BELIEVE IT .... look about 3 or 4 pages back .. i offered it and you all told me that its a waste of time.
Dann2

garage chemist - 1-6-2007 at 06:44

OK, found curent price of ruthenium: about 850$ per ounce.
Thats only slightly cheaper than platinum, while Palladium is very much cheaper than platinum. So you see, recipes using Pd are to be looked for.
I also found a source for Ru powder close to market price (but thats still about twice the price of palladium).

Eclectic - 1-6-2007 at 09:19

Industrial Bullion Prices

I see $540/troy oz. It was $67 or so a few years ago when Pd was $180. Ir was $70!

dann2 - 1-6-2007 at 10:00

Quote:
Originally posted by Rosco Bodine
Industry patents have in general proven to be sources of good information for me anyway , although there are a few
exceptions ...some of which can be debunked with a little effort .

BTW , on your website there is an interesting
article , JES Vol.104, No. 7 (July 1957) page 448
Electrolytic Production of Bromates , which describes
the deposition of massive PbO2 anode material on *iron*
substrate from a *neutral* pH lead nitrate bath . It would hardly get any simpler than that , if a piece of low carbon soft steel would work as well . I am thinking cold rolled bar stock could do the trick as a substrate . or possibly even a soft cast iron , or mild steel .

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...


[Edited on 1-6-2007 by Rosco Bodine]


This set up uses 5 tanks, two stirrers, a pump and constant pH monitoring. Not impossible but not too simple either.
Most people only want to bother with one tank. Perhaps thats the problem.
If you are going to plate any substrate that is attackable by nitric acid from a nitrate bath you must plate with a neutral or near neutral bath. This will require two tanks. It is difficult to keep pH close to neutral as it will drop rapidly as plating commences due to formation of nitric acid.
You cannot do it in a one tank set up IMHO.

Dann2

[Edited on 1-6-2007 by dann2]

garage chemist - 1-6-2007 at 10:08

Hmm, then our sources are contradicting- dont know my source though, it was some website.
Anyway, I cant get it for market price at such small amounts. Its damn hard to find a supplier for this, I called up Degussa and Chemetall and none had Ruthenium or Ru compounds among their products.
My supplier wants 25€ a gram, which is acceptable.

Palladium is still cheaper, and I already have several grams of it.

Rosco Bodine - 1-6-2007 at 10:21

Quote:
Originally posted by dann2
And i see you are offering to plate PbO2 on metals and then ermove the metals .. I CANT BELIEVE IT .... look about 3 or 4 pages back .. i offered it and you all told me that its a waste of time.
Dann2


Just now also replying belatedly to a message from four pages back .....WTF happened to dann2's current post ? Don't be shy and then delete ;) When you have a mouthful of lead salts and iron filings ....spit it out !:D:D

Quote:
Originally posted by dann2
If you are going to get into the business of growing massive Lead Dioxide anode (like growing an anode by starting with 2 cm of Pt.) you will need a well contolled set up. Good pH control, fearly steady Lead Ion concentration, steady temp. etc etc.


A well controlled setup is really what is needed in any case ,
unless you have a relatively huge volume plating bath for
the size of the anode being made , so that its composition changes but very little from the decreasing lead ion and changing pH .

Quote:

Lead Dioxide can be deposited on Pt. It has been done many times when Ti was plated with Lead Dioxide. A thin coating of Pt was deposited first to protect the Ti from the Lead Dioxide.
I was flicking through a library book today and read that Lead Dioxide was known as the 'Poor man's Platinum'. HUH.


Yeah PbO2 was probably used as a protective oxide for preventing the erosion of platinum anodes ....cheaper to have PbO2 eroding away and replace it as needed by replating the platinum with a fresh coat , than to have
platinum steadily eroding as the unavoidable cost of production . That could become costly for huge production facilities making tons of material .
Quote:

You can grow massive anodeS on Iron, Nickle and other wires. It has been done in the journals. The maker started with a close to neutral Lead Nitrate bath and kept plating solution treated with Lead Carbonate etc to neutralize the nitric acid as it was produced to stop it from attacking the Iron, Nickle etc. Well controlled set up.


I can see a problem with growing a coaxial deposit having a wire as its core . The wire limits the amount of current which
can be delivered , while maintaining the same current density
for plating upon an exponentially expanding outer surface would require ramping the voltage to overcome the IR loss in the wire . It would be entirely better from an electrical supply side perspective to be depositing the plating upon a planar substrate whose surface area of accumulating deposit is relatively constant .

But the truly interesting aspect of the massive PbO2 anode
capability is that it may be deposited from a neutral pH bath
of lead nitrate , ( and perhaps from other neutral salts ) upon
an ordinary *iron* substrate . It would seem that exploiting
this cheap *iron* material as a temporary substrate , would make available a lot of money which might otherwise be spent upon exotic and expensive substrates , which could be much better spent on the apparatus for closely controlling the quality of the plating bath itself to produce massive anodes which have a service life of longer than one year while being made of only cheap material .

[Edited on 1-6-2007 by Rosco Bodine]

Rosco Bodine - 1-6-2007 at 10:33

Quote:
Originally posted by dann2
Quote:
Originally posted by Rosco Bodine
Industry patents have in general proven to be sources of good information for me anyway , although there are a few
exceptions ...some of which can be debunked with a little effort .

BTW , on your website there is an interesting
article , JES Vol.104, No. 7 (July 1957) page 448
Electrolytic Production of Bromates , which describes
the deposition of massive PbO2 anode material on *iron*
substrate from a *neutral* pH lead nitrate bath . It would hardly get any simpler than that , if a piece of low carbon soft steel would work as well . I am thinking cold rolled bar stock could do the trick as a substrate . or possibly even a soft cast iron , or mild steel .

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...


[Edited on 1-6-2007 by Rosco Bodine]


This set up uses 5 tanks, two stirrers, a pump and constant pH monitoring. Not impossible but not too simple either.


Think outside the box for a minute and realize that 5 separate tanks are not required , just because that is how they accomplished the desired result for an industrial scale apparatus . An aquarium power filter with the neutralizing salts in the filter would accomplish the same thing . Two tanks only would be convenient , and actually one of those
could be the filter tank compartment of the power filter itself .
Quote:

Most people only want to bother with one tank. Perhaps thats the problem.
If you are going to plate any substrate that is attackable by nitric acid from a nitrate bath you must plate with a neutral or near neutral bath. This will require two tanks. It is difficult to keep pH close to neutral as it will drop rapidly as plating commences due to formation of nitric acid.
You cannot do it in a one tank set up IMHO.
DANN2


Actually a one tank setup is possible if you have one of those miniature submersible magdrive pumps like are used for tabletop fountains .

http://www.pondland.com/product_info.php/cPath/1/products_id...

You would simply put the submersible pump in the bottom of the plating tank , and bring a discharge tube straight up from it to discharge into a receiving vessel above , which has a bottom drain , and an overflow tube also coming down to the drain would be good . The vessel would be a percolation
funnel having a wad of polyester filter fiber in the bottom ,
maybe a layer of diatomaceous earth filter aid above that ,
and then a loose wad of filter fiber whose space is loaded with solid particles of lead oxide or basic lead nitrate , for
neutralization of the electrolyte which percolates by gravity
through the vessel . Something like this could be made from
an empty plastic bottle with the bottom cut off and inverted ,
or from an old filter housing or plastic cannister , or even a section of PVC pipe . The setup would function in the same way as the drawing of Fig.#4 in the patent US2492206 .
This is something that could be done for a small scale cell , perhaps even for a gallon jar sized plating tank .

[Edited on 1-6-2007 by Rosco Bodine]

Palladium vs Ruthenium

jpsmith123 - 1-6-2007 at 17:35

When I first started looking into this, Ru was cheaper than Pd!

Going by the Englehard data that Eclectic linked to, it looks like Ru really took off last year for some reason, but prior to 2006, AFAIK, Ru was usually significantly cheaper than Pd.

Anyway I'm attaching a patent that you might find interesting. It looks like an attempt to find an alternative to Beer's MMO patents. According to these inventors, Pd is better than Ru as far as electrocatalytic activity is concerned. They find that PdO by itself didn't adhere well to the titanium.

And they ended up with a PdO/Pt-Pt alloy or something like that.

[Edited on by jpsmith123]

[Edited on by jpsmith123]

Attachment: 4313814.pdf (446kB)
This file has been downloaded 671 times


garage chemist - 1-6-2007 at 23:27

The processes described in that patent sound really complicated, with baking at defined temperatures and for defined time.
I also consider my platinum too valuable to use it in a way that is so uncertain of success. If the electrode doesnt work, I'm left with the work of recovering and separating the Pd and Pt from the solution and surface of the failed electrode which is going to be very tedious.

Oh well, I probably wont get around ordering two or three grams of Ru. One try with a pure PdO coating, and if it fails its time for ordering Ru and TiCl4.

jpsmith123 - 2-6-2007 at 03:55

If it were me I don't think I would bother with the process in that patent...I think that was mainly an attempt to find a proprietary alternative to Beer's MMO technology.

What I thought most interesting about that patent was the brief discussion comparing the catalytic activity of the various PGMs.

Maybe you could try a PdO/TiO2 (electrodeposited or baked on) coating in the molar ratio suggested by Beer? Seems to me that's the logical place to start. You can get 5 grams of PdCl2 on ebay for $80.00.

http://cgi.ebay.com/Palladium-Chloride-ACS-pure-Photo-5g_W0Q...

All you need is iron

Rosco Bodine - 2-6-2007 at 07:39

All you need is iron ,
All you need is iron ,

All you need is iron , iron .....

Iron is all you need
Iron is all you need
Iron is all you need

:D:D:D:P:D;):cool::cool::cool::D:D:D:D


http://www.youtube.com/watch?v=Z05zPJKasDw

Attachment: allyouneed.mid (43kB)
This file has been downloaded 879 times


Eclectic - 2-6-2007 at 08:13

I think all you need is lead free 95/5 solder, Muriatic acid, and a self cleaning oven to make Sn/Sb oxide coated titanium, coated or not with PbO2. Oh, and maybe some oxalic acid to strip the oxide off of the Ti first.

If you use a closed end Ti tube, you could pour molten aluminum around a copper bus bar in the center and never have to worry about making a good electrical connection. :D

Rosco Bodine - 2-6-2007 at 08:39

Iron , Iron , Iron
Iron , Iron , Iron
Iron , Iron , Iron

Iron is all you need ! :D

Spend the money you would spend for your titanium
on a fountain pump instead :) And save a bit for
a silver bullion coin , for plating a contact surface .


BTW , a bit of background for the youngsters
concerning that video clip from forty years ago ....

It was the first live global television broadcast from
linked satellite feeds .....and the subject matter
was the rock and roll group called The Beatles
offering a message of peace and love to planet earth :D

Here is an interview about the broadcast .

http://www.youtube.com/watch?v=ef-6zix0YNg&mode=related&...

Pretty cool .......huh ? :D

Also cool was that it was an unrehearsed and never
performed song , which was improvised for the occasion
and performed for a world audience .....
which is something requiring a lot of talent and
a major set of balls :D

But the songs performance came off very well ,
and it became a very famous song .

alancj - 2-6-2007 at 17:47

All you need is love, and a nice -big- PbO2 anode... :) (sigh).

-Alan

hashashan - 3-6-2007 at 04:19

3 anodes burst into flames. damn

Finaly i made 3 nice anodes on plastic subtrce, conected them with the silver paint.. started to run nicely, after couple of hours .. puff no anode.

is there a minimal thickness of the coating? maximum current? is the paint good enough contact? what is the best way to connect to the paint?

anyone made the paint by himself? im starting to run out of paint(and it isnt cheap)

dann2 - 3-6-2007 at 04:37

Quote:
Originally posted by hashashan
3 anodes burst into flames. damn

Finaly i made 3 nice anodes on plastic subtrce, conected them with the silver paint.. started to run nicely, after couple of hours .. puff no anode.

is there a minimal thickness of the coating? maximum current? is the paint good enough contact? what is the best way to connect to the paint?

anyone made the paint by himself? im starting to run out of paint(and it isnt cheap)


Hello Hashashan,

What sort of power supply are you using with the anodes.
(You probably answered this before :()

It is strange that they are going on fire!!
Usually if the anode fails due to a bad connection or cracked Dioxide or bad/discontinous Dioxide the current simply decreased to the point where it is very low or non existant.
The only time I had a problem like this was when I used a welder to put current into cell. You program the current but if you start to get a bad connection somewhere the voltage will rise and rise (up to approx. 100V) accross connection, a huge amount of power will be dissipated (it will go red hot.).
Are you getting smooth, good quality coatings on the anodes or are they bad quality nodular coatings.

Dann2

hashashan - 3-6-2007 at 05:04

The PSU is a computer supply. i conect the 12V conection and the current is held at about 10 amps.
the anode heats a lot and then it just catches fire.

the coating is quite smooth although not perfect

Do you use the paint? what do you connect to the paint? i used a platinum wire, or several silver wires.
for some reason the silver wires dont drive current when they are conected to the dioxide directly.

what can be my problem?

dann2 - 3-6-2007 at 05:29

Quote:
Originally posted by hashashan
The PSU is a computer supply. i conect the 12V conection and the current is held at about 10 amps.
the anode heats a lot and then it just catches fire.

the coating is quite smooth although not perfect

Do you use the paint? what do you connect to the paint? i used a platinum wire, or several silver wires.
for some reason the silver wires dont drive current when they are conected to the dioxide directly.

what can be my problem?


The coating of Lead Dioxide is probable too thin and/or off too low a quality, though if you say it is smooth it would appear that the quality is OK. Try putting on a thicker coating.
What is the dimensions of the anode/coating?

When I used a silver paint at the top of a massive anode I put copper braid on top of the silver and then clamped that or wound copper wire around the wad of braid to hold it tightly against the silver. You can get copper braid from TV type cable (co-axial cable).

The fact that you need 12 volts to drive current into cell and through anode + connections is an indication that there is a bad current path somewhere.
The anode I guess since it is igniting!

Lead Dixoide has a conductivity better than most metals. Thats if it is good/fairly good quality coating.

The 'sock' substrate anode that you posted pictures of some time ago had a Lead Dioxide coating that was not of high quality. If you coatings are of similar quality I would expect trouble.

Dann2

hashashan - 3-6-2007 at 05:36

Well i plated at very low currents and the next ones were of much better quality, i didnt understand what you said about my 12V.
i am connecting it to the 12V supply, what is the problem with that?

the dimensions are 10*5 and the thickness is about 1mm(maybe a bit less)

dann2 - 3-6-2007 at 18:49

Hello,

The 5 volt output should be enough voltage to drive a sensible current into a Chlorate cell.
The fact that you need 12 volts seems to me to be an indication that there is something wrong.
Where in the circuit is the 12 volts getting dropped.
When the Anode is working OK most of the voltage is probably getting dropped accross the bulk of the Chlorate solution where that is able to take the generated heat. When a connection (or the Lead Dioxide skin on the anode) in your case starts to become a higher resistance you start to get the voltage dropped accross that section. The power associated with the voltage drop at, say, a crack in the anode is causing it to heat up and ignite.
Try the 5 volt setting, but this is not going to cure the bad anodes. At least the current flow will (hopefully) decrease to a level where you may be able to acertain where the problem is before whole lot goes up in smoke.

Cheers,
Dann2

Inline Pump Idea

Rosco Bodine - 3-6-2007 at 19:10

There is a fairly cheap but good quality magdrive pump which is made for use as a powerhead *or* can optionally be run unsubmerged as an inline pump . They are called Resun King pumps and there are several variants or rebadged versions
available . I have been looking mainly at the Resun King 1 , the smallest , a 10 watt pump , and the Resun King 2 , a bit larger 20 Watt pump .

The pump can double as a plating bath stirrer and pH / lead ion maintainer , performing the circulation task for both simultaneously .

They look like this. The slotted cowling contains a filter sponge which covers an intake hose barb for use when the
pump is used non-submerged , as an external inline pump .
This would be necessary to allow pump cooling if warm liquids were being pumped for example . It also allows for
intake from a tube dropped to the bottom of a vessel and
connected to the intake hose barb on the pump , in cases
where there is not room at the bottom of the vessel or the
presence of the pump would be unsightly or otherwise inconvenient and remote location in inline configuration is necessary .





The pumps have more flow than is needed for circulating
the bath through a pH neutralizing funnel , and the flow would need to be restricted by a valve to keep it from
continuously overflowing the percolation filter with the excess flow . So I figured that the easiest way to manage the flow from the pump would be to split the flow using a Y on the discharge , simply returning most of the pump output along the sidewall of the beaker in which the plating bath is held , to keep it swirling ......serving the function of a stirrer
using the excess flow . A globe valve could be used to restrict the open flow adjustably , and the back pressure at
the Y would divert some of the flow upwards to the percolation funnel above the plating bath . A soxhlet extractor or a pressure equalized addition funnel could be used for the percolation funnel , or one could be improvised .
The discharge flow from the bottom of the percolation funnel
could be delivered through a drop tube near the discharge
of the stirring jet to provide good mixing .

I was looking at what appears to be a knockoff or variant
of the Resun King that is the cheapest one I have found .
The WP22 here at 12.6 Watts is $12.95 plus postage .

http://www.aquaticeco.com/index.cfm/fuseaction/product.detai...

And the cheapest genuine Resun King pumps I found here

http://www.americanaquariumproducts.com/Kingwaterpump.html

$15.99 for the Resun King 1A and $17.99 for the Resun King 2 , plus $7.45 postage for either .

In regards to a different , but related matter ....

These sintered alumina cylinders also caught my notice ,
as the largest one would make a 25 Amp anode if it was
a ceramic substrate . What I thought was if the inside diameter is not too large , it might make a good sleeve around the outside of a rod form massive PbO2 core
having been grown on a wire , for building up its surface
area quickly . The finished anode would be something
shaped like a broomstick concentrically mounted in a soup can . It might also make a good diameter buildup substrate as a wrap for the lower end section of a graphite EDM rod .



http://www.aquaticeco.com/index.cfm/fuseaction/product.detai...

BTW there is another magdrive pump which is cheap and also
is reportedly good quality , called a Maxi-jet ......and one of
the descriptions says that it has inline capability , but other
descriptions say that it must be at least partly submerged ,
so I am not sure whether it is inline capable or not .

The Sen 300 is inline capable .

http://www.aquacave.com/detail.aspx?ID=969

Also the Azoo 1800 at about $20 is inline capable

http://www.drsfostersmith.com/product/prod_display.cfm?pcati...

And BTW these inline capable pumps are useful for water cooling recirculation pumps , like for cooling condensers , water block heatsinks for CPU's ect .


[Edited on 3-6-2007 by Rosco Bodine]

hashashan - 3-6-2007 at 23:56

Quote:
Originally posted by dann2
Hello,

The 5 volt output should be enough voltage to drive a sensible current into a Chlorate cell.
The fact that you need 12 volts seems to me to be an indication that there is something wrong.
Where in the circuit is the 12 volts getting dropped.
When the Anode is working OK most of the voltage is probably getting dropped accross the bulk of the Chlorate solution where that is able to take the generated heat. When a connection (or the Lead Dioxide skin on the anode) in your case starts to become a higher resistance you start to get the voltage dropped accross that section. The power associated with the voltage drop at, say, a crack in the anode is causing it to heat up and ignite.
Try the 5 volt setting, but this is not going to cure the bad anodes. At least the current flow will (hopefully) decrease to a level where you may be able to acertain where the problem is before whole lot goes up in smoke.

Cheers,
Dann2


I use the 12V because my electrodes are at a quite large distance, they are about 10cm away from each other. When i connect th 5V i get only about 4 amps, which is not enough to make perchlorate.
However you might be right about the cracks thing, ill try to grow my anode a bit thicker and ill see what is going on there.
I actually do get the connection are quite hot and i dont know why. I pasted a quite large area with the silver paint and there is no reason for it not to drive the current along the crack even if it exists.


PS. does anybody know how to make the silver paint, i.e. what is the glue that holds the silver pieces together?

Rosco Bodine - 4-6-2007 at 00:45

An electrode spacing of 5 to 8 mm would seem
more reasonable .....10 mm at the most ,
not ten times that . One of the coaxial electrode
arrangements described in a patent was 4 mm spacing ,
but that was in a precisely aligned fixture and using
a pumped electrolyte moving quickly through the gap .
Every time you double the number of mm's distance
for the electrode spacing ......you also double
the voltage drop for keeping the same current .

For example if you have plates 10 mm apart
and the cell is drawing 20 Amps at 6 volts ,
if you move the plates to 20 mm apart then
it should take 12 volts to produce the same current ,
but you are dumping the wasted power as heat ,
not making any more perchlorate , because it is the
Amperes passed that does the work . So for best
power efficiency , you want the voltage as low as you can use and still achieve the 1.3 amps per square inch
of anode current ..or more , that you want for a PbO2
anode .....about 0.2 A per square cm of anode surface .

Sheesh , I bet that cell you are using runs hot .
It would have to be dumping 90+% of its real
power as heat instead of making anything .
You wrote your anode is about 1 mm thick , and
it needs to be at least 5 times that thick probably
to carry the current . Thicker is better .


[Edited on 4-6-2007 by Rosco Bodine]

hashashan - 4-6-2007 at 01:05

Good to know, thanks that really mightbe my problem.
I was told to take a big gap in order to avoid cathodic reduction. I dont have a persulfates or Flurides so i need some way to avoid reduction.

Ill try to make a short gap. And my cell does get hot but not too much, it reaches about 60c but doesnt go above that(Hey it is in a bucket full of cooling water :D)
Ill try to combine all that you have said, thanks a lot :)

Rosco Bodine - 4-6-2007 at 01:29

You could sort of reverse engineer what is the cross sectional area of the PbO2 needed per Ampere of
current required for the surface area of the anode ,
and determine how thick the anode needs to be in
relation to its surface area to safely conduct the current .

If you take that Bromate patent for example and look at
the dimensions of the anodes compared to their thickness , that will get you in the ball park for what a production electrode requires . You know what they state
as the current density at which the cell is being run in production , so you just do the math .....and you can figure out what you will need to adapt that scenario
to your own . The folks who applied for the patent
already did the work .....so just steal their numbers as
a starting point for copying success into your own design .

Even though that is a bromate cell , it shouldn't matter ,
as too much current would burn up an anode regardless
of what sort of cell it is in or what is being made . So in that respect the bromate cell data is transferable to any
other cell using a massive PbO2 anode .

hashashan - 4-6-2007 at 02:08

i just left the plating running and when to study :). i guess when ill get back home ill have a nice 1cm thick anode and that will be 100% enough

Rosco Bodine - 4-6-2007 at 09:45

The art of plating , no matter what is the material being plated .....from everything I have read describes a process which must be closely controlled within certain
limits to produce a structurally sound deposit . The pH
and the temperature and the concentration of the material in the plating bath which is being consumed by the process , and the plating current must *all* be kept controlled to achieve the best plating . The conditions
in the plating cell have to be optimized and then kept constant .....with the exception of the current which might be deliberately varied for fixed periods . Otherwise , if you haven't set up a cell with something in the way of automatic controls , then you have to manually baby sit the process , or have a cell set up so
that as the process runs , the changes do not exceed
a certain permitted range of change in the composiition
for the electrolyte .

That is exactly why I am looking at *pumps* in order to
set up a tank where I can regulate everything in order
to remove the variables as much as possible from the
process . I figure if there was an easier way to get good results , then the penny wise folks in industry wouldn't have ever bothered with all the extra work and detailing
what was required to achieve success . I may simplify
the configuration considerably for a smaller scale process , but the idea is to keep the reaction conditions as close to identical as I can make them to what was reported to work . That will rule out a lot of variables
when it comes to troubleshooting any problems , or tweaking the process later .

Keeping the bath circulating by some method is necessary , and a stirrer or a pump is unavoidable unless
the electrode assembly itself functions as a pump of sorts to keep the liquid flowing . That is why my attention very
quickly was drawn to little magdrive pumps . I think it is possible to do a labscale duplication of the industrial scale methods , since those methods were almost certainly piloted and prototyped on a labscale first and then scaled up for the plant scale tanks . With plating methods having been around for more than a hundred years , and the basics having been pretty well established , there is no need for us to try to reinvent the wheel .....but more for us to *copy* what works ,
and maybe see little refinements which may be possible .

Concerning surfactants or plating "conditioners" which might improve the density of the plating , there are a few others
which might be worth a try . Phenolpthalein , ethanolamine ,
and betaine are things that might be worth a try as small
percentage additives . Sulfanilic acid is another amino organic compound I didn't see mentioned , but also might be worth trying , as it also has surfactant properties .

[Edited on 4-6-2007 by Rosco Bodine]

12AX7 - 4-6-2007 at 14:05

*Shrug* copper is effortless to plate, given some thiourea. Strong (about half strength of saturated) solution of CuSO4, dash of sulfuric acid, couple drops of thiourea solution, add a moderate current and go.

But on the other hand, I've discovered zinc is a bitch to plate. It really likes water and either foamy or crystalline deposits...you may be on to something about control...

And that's to say nothing of PbO2, but that's something still completely differentER...

Tim

[Edited on 6-4-2007 by 12AX7]

Rosco Bodine - 4-6-2007 at 17:18

Quote:
Originally posted by 12AX7
*Shrug* copper is effortless to plate, given some thiourea. Strong (about half strength of saturated) solution of CuSO4, dash of sulfuric acid, couple drops of thiourea solution, add a moderate current and go.


Copper might also plate out well from the same sort of amine or ammonia complexation baths as would silver and probably nickel and probably zinc also since they all form polyamino complexes . Ammonium acetate or possibly ammonium nitrate and free ammonium hydroxide are additives to the alkaline plating baths . The problem I think with the close to neutral pH baths would be hydrolysis causing some metals like Tin for example to precipitate , as their basic salts are nearly insoluble .

No problem in that regard for basic lead nitrate , as it is nearly half as soluble as the normal nitrate . It would seem that PbO2 should plate onto copper , since it plates onto iron ....
but I never saw it described and it may just not work at all
or it may work fine ...I don't know . But there is one way to find out , try it and see what happens . There is also a technique of amalgamating the surface of some metals which
may be difficult to plate , and then plating onto the amalgam
which breaks the surface oxide . Whole books and sets of books have been written on plating as part of the metal finishers industry .
Quote:

But on the other hand, I've discovered zinc is a bitch to plate. It really likes water and either foamy or crystalline deposits...you may be on to something about control...

Yeah at the very least a good flow of fresh electrolyte across the surface is required since that is the conveyor that keeps the ions supplied that are being plated out . If you don't have a steady flow of electrolyte then it is left to chance what is the composition of the relatively stagnant liquid which
may set up its own peculiar laminar flows having swirls and eddies and variable composition depending only on where bubbles are forming and thermal currents are flowing by chimney effect . But a forced flow of electrolyte takes those variables out of the picture .
Quote:

And that's to say nothing of PbO2, but that's something still completely differentER...

Tim

[Edited on 6-4-2007 by 12AX7]


Yeah it is different being that the plating of PbO2 is actually anodizing ....exactly the opposite of metal plating which is a cathode process . But the same rules apply to doing good chemistry , and the same surfactants good for a cathodic
process may also be good for the opposite polarity . In fact some of these processes are entirely reversible by the flip of a switch .

One of the things about which I have been wondering concerning the plating of PbO2 and maintaining the Pb ion
relates to using a sacrificial " pH - trode " , perhaps amalgamate the surface of some lead sheet using mercuric nitrate in dilute nitric acid and hang these amalgamated lead sheets as spectator "neutrodes" in the electrolyte for maintenance of the pH and replenishment of the lead ions . This amalgamation should break the oxide which would normally be on the sheet lead and render it sufficiently vulnerable to increasing acidity of the bath ....
so that an equilibrium might be established in a pH range
moderate enough for good plating performance . The idea is
that the "neutrode" sheet lead would simply be eaten away by the increasing acidity of the electrolyte as the lead in solution is plated out as the dioxide , and this would eleminate having to use any lead oxide or basic lead salt separately for pH control .

Many metal plating processes use an anode made from the metal that is being plated and it is sacrificed and corroded away as the plating proceeds . Of course this is straightforward when the metal plating uses that polarity ,
as the anode is conventionally the sacrificial part . But hydrogen evolution on the surface of the cathode would likely
protect a sheet lead cathode from attack in a nearly neutral pH bath , so it may not just work to use an amalgamated lead sheet cathode . Maybe ...maybe not ....I don't know .

dann2 - 4-6-2007 at 17:58

Quote:
Originally posted by hashashan
Good to know, thanks that really mightbe my problem.
I was told to take a big gap in order to avoid cathodic reduction. I dont have a persulfates or Flurides so i need some way to avoid reduction.

Ill try to make a short gap. And my cell does get hot but not too much, it reaches about 60c but doesnt go above that(Hey it is in a bucket full of cooling water :D)
Ill try to combine all that you have said, thanks a lot :)


I have never heard of keeping the electrodes apart to stop reduction at the cathode.
I do not think that the spacing of the electrodes will make any difference to reduction at the cathode.

Where did you hear that?

60C is hot.

Cheers,
DANN2

hashashan - 4-6-2007 at 22:54

Never mind, one of my friends told me that, usually he does know what he's talking about.
But if you say that it doesnt really matter ill try to take about 1cm distance with 5V(damn there's going to be a high current)

Rosco Bodine - 5-6-2007 at 00:12

Quote:
Originally posted by hashashan
Never mind, one of my friends told me that, usually he does know what he's talking about.
But if you say that it doesnt really matter ill try to take about 1cm distance with 5V(damn there's going to be a high current)



Since you can't adjust the voltage , then you have no choice but to adjust the spacing , and dump any excess
power as heat . You might try the 3.3 volt output for
close spacing . Also you need to hit your target current
based on the area of your anode . So having only fixed
voltages you will have to try different combinations to
find what is most power efficient .

This is where having a laboratory power supply would
make things much better , as you could choose whatever
spacing you want to use , and then just dial in the voltage
which brings the current up to where you want it .

But not having that control , you will have to make the adjustments differently in a less convenient way .

[Edited on 5-6-2007 by Rosco Bodine]

dann2 - 5-6-2007 at 15:35

Quote:
Originally posted by hashashan
Never mind, one of my friends told me that, usually he does know what he's talking about.
But if you say that it doesnt really matter ill try to take about 1cm distance with 5V(damn there's going to be a high current)


Hello,

I am using a computer power supply to power my experimental cells. I can get any current I want (below max. for supply of course) by using an electronic device, a diagram
of which if which is below:

____________________

Diagram above ;)
It is a piece of Nicrome wire. Get a piece from a old electirc fire/heater. Tap the wire where you are getting a current that suits you. If the wire/resistor is too short at the current you
want just use two lengths of the wire (or three or four) in parallel and you can use a longer piece. The wire will get (very) hot but that is not a probem.

Dann2

some new finds

Rosco Bodine - 7-6-2007 at 00:08

Here is a strange one . Reportedly if lead is in contact
with certain other materials , like particles of magnetite for
example , the lead exhibits a self-healing quality under anodic conditions which penetrate an adherent PbO2
coating .....so the exposed metallic lead reforms a protective layer of PbO2 and does not corrode !

Attachment: US3454472 Sintered Lead and Magnetite PbO2 Anode Substrate.pdf (186kB)
This file has been downloaded 722 times


another conductive ceramic anode

Rosco Bodine - 7-6-2007 at 00:17

Here's a different conductive ceramic patent .

BTW , in yet another patent I was reading that there is
a glass formed that is a binary eutectic PbO:V2O5 mp 480C
which has fluxing properties towards other metallic oxides .
I have no idea what may be its electrical properties .

This might have interesting possibilities as a binder
for PbO2 or other conductive oxides , or some mixture
which might form a conductive glass , and have a reasonably low melting point .

Attachment: US3372107 Ceramic anode for perchlorate.pdf (95kB)
This file has been downloaded 673 times


Brainstorming ! Any help available ????

Rosco Bodine - 7-6-2007 at 10:08

In an earlier post I mentioned an idea for a sacrificial lead metal plate to be used in simultaneous fashion within the
PbO2 plating cell , as a means of keeping the Pb content
and the pH constant .....and I am still thinking about this
as the ideal way of keeping the plating bath composition
constant , if it is workable . I had thought of using an amalgamated lead plate as a sort of
" neutrode " as I termed it , a passive lead source which would simply be
vulnerable to corrosion and dissolution by increasing acidity of the bath .

Anyway , I have been thinking more about this and the idea has evolved to consideration of making the consumable lead
part of the same circuit as is used for plating the PbO2 ,
making the consumable lead plate an electrolytically driven
" auxilliary anode " which would be solubilized to replenish
the Pb content of the bath , at precisely the same rate as
is Pb being plated out as PbO2 .....so that the Pb content
of the plating bath and also the pH , is held constant .

This might require the use of two separate cells with the
common electrolyte circulated continuously in a loop supplying both cells ....but likewise having the two cells
electrode pairs form an electrical series circuit so that
the same current flows through each . In that way ,
the same amount of Pb plated out as PbO2 would be
precisely replaced , and at exactly the same rate .
In this manner the process would self-regulate the
composition of the electrolyte . At the end of the plating
of PbO2 , even after days of operation at whatever variations
of current or temperature within reasonable limits .....the composition of the plating bath would remain exactly where
it started in regards to pH and Pb content . :D

So what do you guys think ? And do you have any suggestions or ideas how this should or should not work ?

For reference purposes , there is a patent US459946 which I attached in the lead salts preparation thread .
The arrangement which I am contemplating for the series
circuit would be to use a power supply negative output lead
to a stainless or graphite cathode in the PbO2 plating tank ,
and placed nearby will be the anode substrate onto which the PbO2 will be plated . An electrical cable connection is made to the substrate and the opposite end of the cable is connected to a cathode plate of graphite or stainless in a second tank (if necessary to be separate ) . Spaced nearby this cathode in the second tank is a lead sheet anode having electrical connection to the positive output of the power supply so that the two cells operate in series . Of course a higher voltage will be required to drive the desired current through the two cells in series .....but the idea is that for every mole of PbO2 which is plated onto the anode substrate in the first tank .....exactly the same mole of Pb metal will be driven into solution as a result of dissolution of the lead sheet anode in the second tank .

[Edited on 7-6-2007 by Rosco Bodine]

Twospoons - 7-6-2007 at 15:13

Here's a synthesis for magnetite, to go with Rosco's "lead + magnetite" patent.

[Edited on 8-6-2007 by Twospoons]

Attachment: magnetite_Synthesis.pdf (124kB)
This file has been downloaded 1376 times


Rosco Bodine - 7-6-2007 at 16:11

The patent did say that the synthetic magnetite material could be used :D

In some of the patents which I have seen describing electrodeposition , there has been reference to producing a composite plating from a bath containing
suspended particles which become trapped in the layer of material being plated .....even inert particles of silica or teflon can be trapped in the material being plated to form a composite . So I wonder if a composite plating of lead metal having entrapped particles of magnetite might be made this way , or in some variation of the method .
It would probably result in an even denser layer of better interlocked materials than any sintering could achieve .

Magnetite is also a material of interest , along with some other conductive oxides , like tin , titanium and bismuth ,
which have interest as possible components of a conductive ceramic or glass . Such a composite material could be a sort of holy grail anode material , even if it ended up requiring arc furnace temperatures to melt the stuff .

[Edited on 7-6-2007 by Rosco Bodine]

Perchlorate Cell same as Bromate Cell

Rosco Bodine - 8-6-2007 at 08:53

Earlier in the thread I pointed out the Bromate Cell article
which is posted on the following page
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
saying that the massive PbO2 anode described for the bromate cell is applicable to a perchlorate cell also ,
and this has been confirmed by the attached article .

The massive PbO2 anodes were used in service for two years without failure , and the anodes were originally grown on an *iron* substrate .

Hmmmm , Guess that means for a temporary substrate .....

All you need is iron ,
All you need is iron ,

All you need is iron , iron .....

Iron is all you need
Iron is all you need
Iron is all you need

:D:D:D:P:D;):cool::cool::cool::D:D:D:D

Sound familiar ????

[Edited on 8-6-2007 by Rosco Bodine]

Attachment: Electrolytic Production of Perchlorate by Lead Dioxide Anodes JES 116 Issue 2 pp 203-207.pdf (625kB)
This file has been downloaded 1657 times


dann2 - 8-6-2007 at 17:15

Hello,

So it's back to the five tanks, pump, two stirrers, 66 hours (monitored if not using good automatic equipment) plating time, heater, no mention of tank size, but probably bigger than any tank I (you?) are willing to afford.


All you need is a stack of cash
a stack of cash....
[insert looney tune here]


Good night.

Dann2

:D

jpsmith123 - 8-6-2007 at 18:28

I wonder how much this place wants for PbO2 anodes? It seems once you're making them on a production line it shouldn't be all that expensive...especially in a country like India. I think I'll email them and ask the price.

http://www.titanindia.com/ledma.htm

Rosco Bodine - 8-6-2007 at 19:14

Quote:
Originally posted by dann2
Hello,

So it's back to the five tanks, pump, two stirrers, 66 hours (monitored if not using good automatic equipment) plating time, heater, no mention of tank size, but probably bigger than any tank I (you?) are willing to afford.


According to you it's that way , because you aren't considering what I said already about it being much simpler .
I even posted a picture of an inline magdrive pump ,
and attached a patent US2492206 , drawing Fig.4 showing a simpler plating arrangement to make it clear . I said you need to think outside the box concerning the industrial scale to lab scale conversion , and see how the process can be adapted .

But you have such tunnel vision about titanium substrate
anodes , that you seem in denial that tons of perchlorates
have been made using less technically difficult and less expensive anodes . I even posted a patent which showed
how bare graphite anodes have been used in divided cells
that did work , a long time before any internet usenet dubious designs may have oversimplified what was required . Even so graphite works for somebody who knows how it must be used , and dittos for PbO2 .

The massive PbO2 anodes of the JES Bromate and Perchlorate articles are essentially the same size as
what alembic made on a titanium substrate , and the same precise control of the bath conditions is required for the
making of either . The real difference between the two
is that the low tech version is cheaper and easier to make
and will last longer .

But to those who are singing the praises of titanium substrate , the truth of that is irrelevant .

Quote:

All you need is a stack of cash
a stack of cash....
[insert looney tune here]


A stack of cash isn't required unless you are shopping for
titanium and the dopants needed , when NONE of that is required .....but is simply a high tech way of producing
a perchlorate anode substrate that is inferior to the working material that coats it , and producing a composite that is no better than its weakest link . Keeping at that effort is what seems looney . I mean what is the point ? You go on and on about the complexity and fragility of a massive PbO2 anode , when that design has been proven in commercial use to be the most easily and economically attained of the durable anodes . On your website you even said that the best substrate is no substrate at all , so I should be preaching to the choir here . But I guess you are now
dedicated to the "false religion" of titanium substrates
and exotic "paint and bake" semiconductor junctions , which
then get what for advantage but many prayers the sacred
coatings don't crack .

Quote:

Good night.

Dann2

:D


Good night indeed !
Jesus Christ would be more like it ....:D
but then who's swearing?

Think of PbO2 on iron as that "old time religion" that just works , and stop hanging out with the Moonies and the Dianetics crowd !

Where I am at now is choosing the best scheme for keeping the Pb content and pH of the plating bath constant .
I grabbed all sorts of references for the preparations
of the basic salts that would be the simplest way . And I have also been looking at the possibility of using an active
electrolytic method for doing this ....but will probably just use
the percolator funnel setup since it is simpler .

I have found another patent which further substantiates
that industry has used not just iron but steel as a substrate
on which to electrodeposit PbO2 for massive anodes . I found a patent which describes a method used by the plating shops for cleaning the substrates of PbO2 residues
prior to the replating of new PbO2 anodes . It is US5487820 attached . Given these patent and literature references
which are related to industrial use of long lived and durable and cheap massive PbO2 anodes , which have also been prototyped on a lab scale , a few people seem to be in some sort of denial that this would be a very logical approach .

And all I can say to the notion that somehow *any* substrate is going to be superior to the massive PbO2
configuration .....is :roll: , hope springs eternal .

BTW .....WTF happened to the roll eyes icon ,
was it not PC ??? I mean was it too provocative and insensitive , too offensive to any genuine intellectuals
who otherwise might contribute something here if
only this were a more tolerant and nurturing environment :P

There are several patents which have mentioned the use of
steel or iron as a temporary substrate upon which massive PbO2 anodes may be plated . US2846378 , US2945790 ,
US4064035 are three of them and there are others I don't have handy . Those patent references along with the JES
description are very thorough and credible . And according
to US4064035 it is less than a one day plating time to buildup
a massive PbO2 anode .

From everything I have read this looks like the best way to go and has been well proven for fifty years .



[Edited on 9-6-2007 by Rosco Bodine]

Attachment: US5487820 removing PbO2 from steel substrate anode.pdf (49kB)
This file has been downloaded 672 times


Eclectic - 9-6-2007 at 06:00

Rosco, are you declaring a Jihad against titanium? Are not ALL elements precious in the eyes of God? Can't ALL the elements just get along, preferably in complex, intricate, interesting ways?

:P:D;)

old time anode hour from the lead crystal cathedral

Rosco Bodine - 9-6-2007 at 09:51

Woe unto you sinners ! Hear the word of Plumbum ,
heed the word of Plumbum , thus sayeth Plumbum .

I AM your perchlorate anode , PbO2 .
Thou shalt have no other perchlorate anodes before me .
For I your PbO2 perchlorate anode , am a jealous perchlorate anode . I will bless them who bless me , and curse them who curse me , even to the third generation :P

On my right hand , since from the beginning there was iron , and all ye who knoweth me shall rule over the plating baths with a rod of iron ;)

I know the works of those who goeth the way of titanium and platinum and how the false prophets deceived them
with miracles to cause them to be astonished and bow down before false anodes . Surely all of these shall have their reward in the day of corrosion :D

BTW , here is the pdf for that JES article on bromates
which Dann2 has on his website as a jpg file . This is such an important reference , it needs archiving in that
conventional file type . @ dann2 , please for any of the
files which you may accumulate related to your website , if you have the root files in pdf , link them , as they are
simpler to handle for printing , ect .

In that patent US4064035 , which mentions iron as a suitable substrate for massive PbO2 anodes , it further
says that following the plating , the iron substrate may be etched away by acid .....but gives no further details
concerning this method of stripping the massive PbO2 anode from substrate . I am wondering specifically what
composition of etchant would be most desirable , which
would thoroughly eat away the iron , while not attacking the PbO2 in any harmful way . Perhaps a mixture of
hydrogen peroxide and sulfuric acid ? Any ideas what
would be good for this ?

Attachment: JES 104 Electrolytic Production of Bromates.pdf (383kB)
This file has been downloaded 1048 times


Eclectic - 9-6-2007 at 10:19

I think if you just operate the anode in a chlorate cell, maybe with some additional HCl, the iron will dissolve, maybe plating out on the cathode. Or maybe set up something like a lead/acid battery with stainless steel cathode. Make high purity electrolytic iron.

This could also turn into a Holy Crusaide! Pure Iron (Armstrong Iron) is as scarce as Archaeopterix teeth. Pure Iron crucibles, or heavily plated with pure iron crucibles would be very useful for experiments with molten Lithium compounds. Everything else seems to react or dissolve (although I suspect pure alumina crucibles would form a protective layer of lithium aluminate below 1200 C.)

iron plating on aluminum pistons

Rosco Bodine - 9-6-2007 at 10:46

Iron can be plated onto aluminum as can nickel .
This might have some usefulness . See US5368719 .

BTW , my EDM graphite arrived . I have several sheets
that are 8 mm thick , 125 mm wide , 375 mm long .
I was going to split them lengthwise as substrates for
PbO2 . I also got some round rods 1" and 3/4" for
GSLD experiments .

My time for any of this is about to get hijacked for awhile
as I have assorted other business which requires my attention
and I am reaching a "stopping point" where I
pretty much have the research done , and can implement
and experiment later . This seems to be the story of my life ,
spending time digging up references and getting experiments
planned , and then having no time left to do the fun part . I have a stack of hardcopy file folders two feet high of uncompleted experiments , and boxes of unassembled parts for apparatus for uncompleted projects ....I swear I need three or four assistants and a secretary . Posting some of it here , maybe somebody else can make use of the information and ideas already accumulated .

Attached is a good primer concerning the conditions under which various forms of lead oxidation products are evolved and/or electrodeposited .



[Edited on 9-6-2007 by Rosco Bodine]

Attachment: JES The Anodic Oxides of Lead.pdf (957kB)
This file has been downloaded 1173 times


dann2 - 9-6-2007 at 16:02

Hello,


Quote:
Originally posted by Rosco Bodine




But you have such tunnel vision about titanium substrate
anodes , that you seem in denial that tons of perchlorates
have been made using less technically difficult and less expensive anodes . I even posted a patent which showed
how bare graphite anodes have been used in divided cells
that did work , a long time before any internet usenet dubious designs may have oversimplified what was required . Even so graphite works for somebody who knows how it must be used , and dittos for PbO2 .


The patents never tell you what the failure rates of anodes are. The product they have made/discovered is ALWAYS the best thing since sliced bread.
It is my opinion that the massive, GSLD, ceramic substrate, and any corrodable substrate needs all stops pulled out on quality of plating set up. If you can come up with a cheap set up as a substiture for LARGE tanks and a number of them then that will be great.
Perhaps the Ti with doped Tin will be more forgiving when corners are cut.
Ti is easy to obtain. The substrate will conduct current to the Lead Dioxide if the coating is not perfect and it is self healing where the Lead Dioxide has a hole or imperfection in it.
That is a good starting point for the whole show.
There are no other substrates (bar the possibility of Magnetite but thats another story) that have theses advantages. It must be coated with something (doped Tin) to link the Ti with the Lead Dioxide. But that is not too difficult (we hope).
Quote:

The massive PbO2 anodes of the JES Bromate and Perchlorate articles are essentially the same size as
what alembic made on a titanium substrate , and the same precise control of the bath conditions is required for the
making of either . The real difference between the two
is that the low tech version is cheaper and easier to make
and will last longer .



Massive, Ceramic based, Graphite based cannot be described as low tech. They will kick you in the butt if the coating is not perfect.
Perhaps the doped Tin coated Ti will do the same if all stops are not pulled out on quality of coating set up but we will have to see.
The other substrates have been tried again and again by others out there with out much success.


Quote:

But to those who are singing the praises of titanium substrate , the truth of that is irrelevant .

The other substrates are old and tired and tried again and again. The Ti is the new kid on the block and will work. Have faith!!!!!!!!!
The other have been cursed (literally) by many.

Quote:


You go on and on about the complexity and fragility of a massive PbO2 anode , when that design has been proven in commercial use to be the most easily and economically attained of the durable anodes . On your website you even said that the best substrate is no substrate at all , so I should be preaching to the choir here . But I guess you are now


The Massive anode has not been proven in low tech (one tank) amateur circles. The other substrates have been a bad job too.
I was the first to start singing the praised of the ceramic subatrate anode a long time ago (when god was running around in wee pants, (now that IS quite a while ago)) but is proved to be a totally useless hopeless substrate. Read the patent. It is the best, most robust, better than anything before anode. No mention of salts being conducted up the the connections etc.
On my site I sing the praises of the Massive anode in the form of the Cloth Substrate Anode. I think it is a possible way to go. A piece of cloth (or what ever beats the hell out of Graphite price wise.)

Quote:

dedicated to the "false religion" of titanium substrates
and exotic "paint and bake" semiconductor junctions , which
then get what for advantage but many prayers the sacred
coatings don't crack .


No need to pray quite so hard with the Ti based product as you will need to pray with the non self-healing substrate (or the cracking and falling apart massive (not reinforced with cloth type)) anodes.
With the non self-healing type substrates I suggest a pilgrimage [prayers will be useless]. With the massive (not reinforced with cloth) I suggest you do the pilgrimage on you nees!

Quote:


BTW .....WTF happened to the roll eyes icon ,
was it not PC ???

Yes. If you resurrect that thing I'm leaving :-|


Quote:

....massive PbO2 anode .

From everything I have read this looks like the best way to go and has been well proven for fifty years .


They have been proven for fifty years to be problemetic. This I have read in many places. Low yield when making. Prone to cracking.



Dann2

Rosco Bodine - 9-6-2007 at 18:45

Quote:
Originally posted by dann2
Hello,


Quote:
Originally posted by Rosco Bodine




But you have such tunnel vision about titanium substrate
anodes , that you seem in denial that tons of perchlorates
have been made using less technically difficult and less expensive anodes . I even posted a patent which showed
how bare graphite anodes have been used in divided cells
that did work , a long time before any internet usenet dubious designs may have oversimplified what was required . Even so graphite works for somebody who knows how it must be used , and dittos for PbO2 .


The patents never tell you what the failure rates of anodes are. The product they have made/discovered is ALWAYS the best thing since sliced bread.

Yeah you can get that from reading of the patents about the titanium substrate anodes , especially when they fail to provide perchlorate cell performance data , it would seem to be a glaring omission .



Quote:

It is my opinion that the massive, GSLD, ceramic substrate, and any corrodable substrate needs all stops pulled out on quality of plating set up. If you can come up with a cheap set up as a substiture for LARGE tanks and a number of them then that will be great.


Yeah I have already spoken to that twice . The scale is different for producing one 40 Amp anode , than for making a dozen that size at one time , and you don't need as much plumbing to accomplish the same thing . It isn't required to have the same arrangement .....only the same functions . Scaling down often simplifies things .

Quote:

Perhaps the Ti with doped Tin will be more forgiving when corners are cut.


Why would you think that any corners could be cut making an anode which has a compromisable substrate buried at its core ? If anything , the plating is even more important to be
impermeable . And as for the substrate being self-healing ,
well is that indeed a capability for the valve metal substrates ? I missed that in the titanium substrate patents
which I was reading . It was my understanding that when their oxide layer was breached , they were history .


Quote:

Ti is easy to obtain. The substrate will conduct current to the Lead Dioxide if the coating is not perfect and it is self healing where the Lead Dioxide has a hole or imperfection in it.


References??? Again it was my understanding that
during service in the perchlorate cell , there is no self-healing
for titanium substrates , they corrode , only more slowly ,
if their semiconductor oxides are breached , which occurs
sometime not so long after the PbO2 layer is breached ,
similarly as occurs for graphite . The PbO2 will even separate from a platimum substrate , if the PbO2 is permeated by electrolyte while in service .

Quote:

That is a good starting point for the whole show.
There are no other substrates (bar the possibility of Magnetite but thats another story) that have theses advantages. It must be coated with something (doped Tin) to link the Ti with the Lead Dioxide. But that is not too difficult (we hope).


So are you saying the semiconductor oxides coated titanium
has the same self healing bielectrode activity as occurs with
lead-platinum , and lead-magnetite ...and is this proven to work in perchlorate cell conditions that the self healing occurs ? Again ....what references ?



Quote:

Quote:

The massive PbO2 anodes of the JES Bromate and Perchlorate articles are essentially the same size as
what alembic made on a titanium substrate , and the same precise control of the bath conditions is required for the
making of either . The real difference between the two
is that the low tech version is cheaper and easier to make
and will last longer .



Massive, Ceramic based, Graphite based cannot be described as low tech. They will kick you in the butt if the coating is not perfect.
Perhaps the doped Tin coated Ti will do the same if all stops are not pulled out on quality of coating set up but we will have to see.


I think you may rely upon it that carefully controlled plating conditions for the PbO2 are going to be required in any case . No sloppy work is going to produce a good anode no matter what configuration it is .



Quote:

The other substrates have been tried again and again by others out there with out much success.



Maybe the "peer review" problem there is that the reviewers
aren't duplicating the conditions of what it is they are reportedly debunking . There is a lot of that going around you know , so some of this I just have to see for myself .
When there is so much of what should be reliable literature
on a subject that is so mundanely industrial , and such controversy erupts .....you would find even in the text of the literature itself many disputes of the findings of earlier workers very prominently published ...and I haven't been seeing that in literature spanning decades of work , so it just doesn't wash that the data or its continuity is likely to be unreliable . Maybe it is unreliable only for those who are
not seriously adhering to the science and doing good work , but are making half-assed attempts which fail , and then
saying that the published science is bad instead of their own methods .


Quote:

Quote:

But to those who are singing the praises of titanium substrate , the truth of that is irrelevant .

The other substrates are old and tired and tried again and again. The Ti is the new kid on the block and will work. Have faith!!!!!!!!!
The other have been cursed (literally) by many.


There is nothing tired about a perchlorate cell that has an array of 10 anodes running for two years without replacement of a single one due to failure . I'd say that's a pretty solid proof of concept . And if it wasn't , you can bet your ass that the peer review process would have crucified
the authors as if they had been reporting cold fusion .
There would be plenty of debunking , done loud and long
in the same journal and in other places .....so where is it ???
If the technical accuracy is not there , then where are the
subsequent articles clarifying the matter ????

Quote:

Quote:


You go on and on about the complexity and fragility of a massive PbO2 anode , when that design has been proven in commercial use to be the most easily and economically attained of the durable anodes . On your website you even said that the best substrate is no substrate at all , so I should be preaching to the choir here . But I guess you are now


The Massive anode has not been proven in low tech (one tank) amateur circles. The other substrates have been a bad job too.

If you are looking for a low tech process that is good for amateurs to produce perchlorates .....good luck !!!
I'm serious , nothing about this is really going to tolerate
an absence of quality control , and kitchen chemistry this is not . Chlorates , yes sure .....perchlorates ? No easy
non-technical way .


Quote:

I was the first to start singing the praised of the ceramic subatrate anode a long time ago (when god was running around in wee pants, (now that IS quite a while ago)) but is proved to be a totally useless hopeless substrate. Read the patent. It is the best, most robust, better than anything before anode. No mention of salts being conducted up the the connections etc.

So what ! It requires the same silvered connections same as would a massive anode . Why shouldn't it ?

Quote:

On my site I sing the praises of the Massive anode in the form of the Cloth Substrate Anode. I think it is a possible way to go. A piece of cloth (or what ever beats the hell out of Graphite price wise.)


And a silvered connection will be required there too .


Quote:

Quote:

dedicated to the "false religion" of titanium substrates
and exotic "paint and bake" semiconductor junctions , which
then get what for advantage but many prayers the sacred
coatings don't crack .


No need to pray quite so hard with the Ti based product as you will need to pray with the non self-healing substrate (or the cracking and falling apart massive (not reinforced with cloth type)) anodes.

Cracking and falling apart massive anodes ??? Ten of them
running together for 2 years and not one failed is not a story of fragile anodes ...so what is the truth here ?

Quote:

With the non self-healing type substrates I suggest a pilgrimage [prayers will be useless]. With the massive (not reinforced with cloth) I suggest you do the pilgrimage on you nees!

There you go again with the claim/inference that titanium is a self-healing bielectrode substrate . So where are you getting this information ??

Quote:

Quote:


BTW .....WTF happened to the roll eyes icon ,
was it not PC ???

Yes. If you resurrect that thing I'm leaving :-|

We desperately need to get a Lazarus edition of the roll eyes smilie , maybe have a user option to hide it from the thin skinned ;)

Quote:

Quote:

....massive PbO2 anode .

From everything I have read this looks like the best way to go and has been well proven for fifty years .


They have been proven for fifty years to be problemetic. This I have read in many places. Low yield when making. Prone to cracking.

Dann2


Again , where are you getting this information ????
And don't you find it strange that this contradicts what
the journals and patents describe . I am sure there are
incremental improvements even in the art of manufacturing accordions . But that doesn't mean nobody could play a tune on the ones that were made a hundred years ago ,
or that half of those attempted to be made had to be scrapped as firewood . It isn't like there wasn't some alternative before the invention of fiberglass and electric
organs .

12AX7 - 9-6-2007 at 20:19

Dann: some helpful information.

Leave Rosco alone. It's obvious that he is pushing away all your ideas and leading a rather obnoxiously long argument. Be the better man and win the argument by not replying. He tends to do this, and regardless of the value of his chemical knowledge, he is a terrible person to try to sway.

Changing subject here...

Has anyone tried, say, a lead anode in a high-sulfate solution? Sulfate tends to yield lead dioxide on the anode. Chloride gives a mucky combination of hydroxide, chloride and dioxide, but maybe less chloride (or even starting with chlorate) will be capable.

I suppose the chemical reaction is that, since to metal, chlorate and perchlorate simply corrode it (giving soluble lead), a "catalytic" side-reaction has to be performed, in this case where sulfate oxidizes to persulfate and PbO2 and that sort of stuff. Then the PbO2 is able to oxidize the chlorate. Efficiency will be lower since electrons are spent maintaining a PbO2 layer and producing oxygen, but it would be cheap as hell if all the preparation necessary is lead, possibly dioxidized some before use.

Tim

Rosco Bodine - 9-6-2007 at 20:54

Quote:
Originally posted by 12AX7
Dann: some helpful information.

Leave Rosco alone. It's obvious that he is pushing away all your ideas and leading a rather obnoxiously long argument. Be the better man and win the argument by not replying. He tends to do this, and regardless of the value of his chemical knowledge, he is a terrible person to try to sway.


Tim , I am most definitely *not* simply trying to argue , but really to get at the facts , not anecdotal IMHO's or "I have heards" but good technically valid data . For example , the matter of the bielectrode self-healing substrate aspect of
titanium substrate anodes ....I really didn't catch that detail in any of the stuff I read .....so asking for references was no argument . I really want to know more on that , because the first I saw of it was with the sintered lead and magnetite
scheme , and I never heard of it before , except being used as a galvanic couple for zinc granules having copper regions used as a reducing reagent ....not as an anode .

Really I am not trying to complicate things . And I may be terrible to try to sway when I am right about something ,
but I am not so unreasonable as not to see it or admit it
where anybody can show me I am wrong . I certainly can be wrong about some things , ..... rarely:P

Quote:

Changing subject here...

Has anyone tried, say, a lead anode in a high-sulfate solution? Sulfate tends to yield lead dioxide on the anode. Chloride gives a mucky combination of hydroxide, chloride and dioxide, but maybe less chloride (or even starting with chlorate) will be capable.


I saw one process described where lead metal was first high current plated onto an etched anode , and then the current reversed to anodize it to PbO2 in order to improve adhesion , as it worked better that way than trying to plate on the PbO2 first ....I forget what was the metal substrate , but it worked best to go metal to metal first in that particular case .
Quote:

I suppose the chemical reaction is that, since to metal, chlorate and perchlorate simply corrode it (giving soluble lead), a "catalytic" side-reaction has to be performed, in this case where sulfate oxidizes to persulfate and PbO2 and that sort of stuff. Then the PbO2 is able to oxidize the chlorate. Efficiency will be lower since electrons are spent maintaining a PbO2 layer and producing oxygen, but it would be cheap as hell if all the preparation necessary is lead, possibly dioxidized some before use.

Tim


Are you talking about the bielectrode self-healing PbO2 effect ? It is not established that this is protective in a
perchlorate cell , from anything I have read , but it would be great if it did work . I think what it does is add a galvanic voltage locally which may or may not be effective in a perchlorate cell .....I found nothing else on this .

alancj - 9-6-2007 at 22:22

Rosco, I think what dann2 means when he uses the term "self healing" is that Ti stops conducting and becomes inert in anodic conditions. If a pin hole develops through the lead dioxide and then through the semiconducting layer, it gets to the Ti and anodizes and corrodes no further. It would only break down and corrode if you cranked up the voltage far above what should be present in a perchlorate cell. Obviously the substrate isn’t going to cause the outer peroxide layers reform, the substrate in that spot just becomes inert, so it won’t matter if a hole or crack develops. The whole point of the semiconducting layer is to get past that property of Ti so it can be used in anodic conditions, but if that fails the Ti will just go back to its old self again and reform a nonconducting TiO2 protective layer.

-Alan

Rosco Bodine - 10-6-2007 at 01:16

Quote:
Originally posted by alancj
Rosco, I think what dann2 means when he uses the term "self healing" is that Ti stops conducting and becomes inert in anodic conditions.

Yes , I see what you mean by the insulating of the titanium by titanium oxide interface with the electrolyte , the anodizing would then block current flow there from the electrolyte solution to the metal . But it was my idea that the
insulative area would still be attacked by the chlorine ion which would penetrate that protective oxide , and that the effect would also spread underneath the PbO2 layer causing it to flake off . A variation on the same thing happens even when the substrate is platinum due to the different oxygen evolution voltages bewteen platinum and PbO2 . Oxygen spreads like a sheet of marbles between a carpet and a floor , wedging between the interface and prying the PbO2 away from the platinum . Maybe it has a greater surface tension / adhesion for the platinum and maybe chlorine is involved also , but whatever the mechanism , the PbO2 separates , once electrolyte gets under it . If that effect is absent using the doped semiconductive oxides , so that delamination does not proceed ....then all that would happen
at the location of an area of exposure of the substrate , is that exposed area would simply go inert . I am very dubious about that happening though , particularly in an electrolyte
where a fluorine additive is present ....it just smells like real trouble for the titanium that gets touched by that fluorine , since if the chlorine didn't get at it you can bet the fluorine would . The voltage would be a factor , but that would just accellerate things . I am guessing here . I haven't read the test data . I am sure , now that I think about it , I remember this was definitely mentioned about the use of fluoride .
Maybe a persulfate additive would be better when a titanium substrate anode is in the cell .
Quote:

If a pin hole develops through the lead dioxide and then through the semiconducting layer, it gets to the Ti and anodizes and corrodes no further. It would only break down and corrode if you cranked up the voltage far above what should be present in a perchlorate cell.

Yes I follow what you are saying that it passivates the exposed titanium when electrolyte contacts the metal .
And *if* that is what happens then it would be okay .
So long as the conductive real estate in the surrounding neighborhood isn't affected , it would keep working .
Quote:

Obviously the substrate isn’t going to cause the outer peroxide layers reform, the substrate in that spot just becomes inert, so it won’t matter if a hole or crack develops.
It is more like a self-sealing than a self-healing actually .
Quote:

The whole point of the semiconducting layer is to get past that property of Ti so it can be used in anodic conditions, but if that fails the Ti will just go back to its old self again and reform a nonconducting TiO2 protective layer. -Alan

Yeah , I see what you are talking about with the semiconductor layer . They are basically lowering the reverse
breakdown voltage of the diode junction at the Ti-TiO2 interface so that current can be made to flow backwards through it and into the PbO2 layer . PbO2 actually forms a
rectifying junction on a "blued titania" over titanium substrate . Sheesh I'm not sure , the polarity may be backwards on this one or the reverse breakdown voltage too high for anodic applications , but see the attached
patent US2711496 for any relevance it might have . Curiously , amorphous PbO2 also forms a photorectifier junction on a copper substrate , see US4173497 if that
is of any interest . The point is that the PbO2 itself is an added semiconductor in these layered structures which
could have exactly the wrong polarity , if I have this right ,
and form a blocking diode depending upon what else is
in the "sandwich" of layers . Basically with these doped
oxide layers on titanium then covered with PbO2 what you have assembled is one giant planar zener diode of sorts serving as an anode ? I'll have to go back and refresh read a chapter on semiconductor theory to make sure I have this right :D

BTW , that same patent that was refrenced by Alembic
US2872405 had described using the corrosive effect of
the chlorate cell itself to etch away an iron substrate and leave the massive PbO2 anode intact , without risking breakage by trying to pry it away from the substrate on which it was deposited . So I didn't just dream up that idea
but probably read it and then forgot it . I think Alembic originally gave a British patent number equivalent and I didn't make the connection . Anyway that patent did use
a lower plating curent and did take days for plating a
massive PbO2 anode , but a later patent US4064035 much improves the process in a couple of ways including reducing the time for plating . So there's nothing wrong with gleaning
the best parts from different patents and then combining those refinements . Another patent from the same folks
as Alembics patent reference , is US2859166 which was
a co-application , and it tells more about the use of temporary steel substrates being conventional in the
manufacture of massive PbO2 anodes ....which it also says are very well adapted for the production of perchlorates ,
and should be produced in a thickness of 1/2 to 1 inch
for added strength . Probably the geometry and scale of the anode has an optimum ratio of width , length to thickness
and that is on the large side for commercial sized production anodes . That patent specifically deals with shielding and baffles used in a cell to prevent treeing and produce smooth and even deposits of PbO2 laid down in thick layers to produce such gargantuan PbO2 anodes .

Anyway , I think I'll rest my case that massive PbO2 anodes
are simpler and well proven and involve the same technical requirements for getting the PbO2 part of the assembly done right , as will be required even for the alternative configurations . It just seems much easier to let the same
plating bath run longer , do the silverplated contact , and have a commercial grade production capable anode ...
without venturing into silicon valley styled planar rectifier manufacture , especially if the idea is that simplicity must be kept to what is convenient for a "hobbyist" . Personally my impression is that any of this stuff is well beyond the realm
of most hobbyists and well into the realm of pretty nerdy madscience and its practitioner technicians :D , even for
the simpler configurations .

Attachment: US2711496 Blue Titanium Conductive Oxide Anodization.pdf (295kB)
This file has been downloaded 882 times


hashashan - 10-6-2007 at 01:25

Rosco Bodine, why do you insist to make a massive anode without any subtrace. Dont you think that it would be better to make a thinner anode but with a cloth inside it to improve its phisical strength. Also because you dont plate that much PbO2 so you dont really need to controll the PH which i think is the main problem of the massives. I dont think that anyone would like to make a huge bath (to handle kilograms of lead nitrate) and then to put in pumps (that i think wont make the trick because they do have metallic parts inside them, and we dont really know what is the metal that this part is made of and what will it cause to the tank)

Rosco Bodine - 10-6-2007 at 02:46

I am not insisting that anyone make a massive PbO2 anode without any substrate . It does decrease some the demand for carefully controlled conditions (but it does not eliminate completely the need for any regulation) and is probably the surest , simplest way to make a practical anode *if* you accept the fact that you are going to have to silver the connection .

Some of the magdrive pumps would work fine and have wetted parts that are only polypropylene and ceramic .

It depends on the *size* anode you are trying to make ,
what may look like the best way to go . Lead is very heavy , and it will take a good bit to make a 40 Amp
anode , plus the extra third length needed for the distance above the electrolyte to the silvered connection .
Yes it takes kilograms of lead salts for this , and even
for a cloth substrate anode .....which is still a massive
PbO2 anode . And you will be surprised how little lead
being plated out will drastically change the pH if you aren't actively regulating the pH in some way .

Scaled down , everything is simpler in some ways ,
but not in others .

alancj - 10-6-2007 at 03:59

I was thinking that the surest way to control pH (and therefore lead ion concentration) would be to use a pH probe in the plating tank, and interface that with a microcontroller to drive a small auger to deliver salts to an addition tank, which is circulated with the plating tank. (oddly enough, I live a half mile away from a company that manufactures augers for pellet stoves!) Maybe just knowing the plating deposition rate one could do it without automatic feedback, and skip the probe. I think that is what you'd have to do with an acidic plating bath at least. For a neutral one I think a percolation funnel would be fine, like Rosco mentioned. IMO it would be pretty hit or miss trying to get a lead compound with the right properties so as to dissolve at the exact rate you want at the exact pH etc., in anything but a neutral plating bath.

-Alan

edit: auger not agar!

[Edited on 10-6-2007 by alancj]

hashashan - 10-6-2007 at 04:09

There goes an interesting question :
If we do hang something like a tea bag of lead carbonate(or any other lead compund that will react with HNO3) what will happen? will the trace amounts of HNO3 forming will react immediately with the lead compund hence making a neutral bath. Or because of no movement in the tank the only reaction will be caused by drifting of the solutions and making quite stable acidic PH?

12AX7 - 10-6-2007 at 06:15

*Auger

dann2 - 10-6-2007 at 11:32

Hello,

Regarding the Silver connections needed for massive anode. Silver Perchlorate is an explosive and therefor the Silver must be kept away from the Perchlorate cell. It think it would be prudent to keep it away from a Chlorate cell too.(same goes for Copper).
Silver will not do as an interface coating on any anodes IMHO for this reason along.

Ti is a valve metal (this has been explained by others but since I seem to like typeing..............)
The Valve Metals consist of (AFAIK) Al, W, Ti, Ta, Hf, Nb, Zr. They form oxide coating that are diffucult to penetrate under anodic conditions. Al is useless (only a few volts) W I dont know, it may be a possibility for

the Amateur as it is easily available as a rod in welding shops. It's oxide may not dissolve into our Doped Tin Oxide coating though. Ti is good Ta, Hf and Nb have oxide coatings that are more anodic protective that Ti. Their oxides may not dissolve in out Doped Tin oxide though. Zr.... is it a valve metal??

The DTO is not an attempt to make diodes (zener or otherwise) but simply a way to stop Ti Oxide (non conductive) from forming on the Ti in the presence of Lead Dioxide. It is a cheap alternative for a flash coating
of Pt.

Ta is expensive but is crops up on ebay fairly regularly. The other are too, shall we say, 'exotic'.
Ta is fairly easy to drill and work as I have a piece.
Ti (Grade one) is easy to drill and debur. It is quite soft.

I got some Ti today. It is three mm thick which is a bit thick. I presume

I can make it thinner simply by putting into NaCl and passing current (high enough Voltage).... I might even make some Chlorate as a biproduct, eh.


If the (Per)Chlorate solution has the ability to creep between the Lead Dioxide and the doped Tin Oxide (or between the DTO and the Ti) then the whole idea of 'non-professional' Lead Dioxide coating on Ti will not work I guess as Rosco said. But it will self heal (self seal) at least.

From Industrial Electrochemical Processes (book) page 550 is a graph of Anodic breakdown voltage of Ti (C.P. (Commercialy pure)) as a percentage of the breakdown voltage at 20C in brine solution.

At 20C it is 100% (obviously)
40C 85%
60C 70%
80C 55%
100C 45%

Would this be similar(ish) for Chlorate solutions. I presume it is fair to assume that Ti WILL be self healing in Chlorate.

The value of Ti at 20C in brine is approx. 15 volts, way above anything we will be throwing at it. It increases as current density goes up.
Ta is way above this.

From Electrodes of Conductive Metallic Oxides page 637.

I will put a piece of Ti into a Chlorate/Perchlorate solution, rise the

Voltage and see where it breaks down. I would be better doing it this way than going the theory route .
Ti is used for DSA anodes, where it is self healing.



Regarding hanging a porous packet of Lead Compound in the plating tank it would probably help. The carbonates will cause bubbles. If you could get the hydroxide. Litharge can be hard to get to dissolve but may be the best.
I think you are better off thinking in terms of free Nitric acid in the solution that in terms of pH. The pH is above two, say, it will vary easily. If you simply try to keep the free Nitric acid at a level of about 3 or 4 grams per liter of solution (low pH) this may be the best way to think/go about it. Will a pH meter do this? measure real low pH accurately?
I wonder would a hydrometer in the solution measure the density of Lead Nitrate and give you an idea of how much to dribble in. If dribbling in Lead Carbonate or basic carbonate or hydroxide you are better off making a slurry of theses compounds as when dry they float on the surface making
one hell of a mess.

With the massive anode I notice that is is suggested that it be grown on the INSIDE of a cylinder. I think this suits the internal stress built up on the anode better. If grown on a flat or worse, on the outside of the cylinder they are more prown to failure.
(Can't remember where I read that, it is difficult to remember all sources).

From Chemical Engineering 1965 July 19 page 82:
Below a picture of a large stack of GSLD Anodes:
_____________________________________________
Before Pacific Engineering could make a breadthrough in electrochemical processing, it had to overcome the defects in Lead Dioxide anodes that had plagued previous researchers. These included nonuniform and nonadherent coatings that were too course and porous, short electrode life due to corrosion and inability to stand up to typical commercial handling.
bla bla,
Pacific makes its anodes by first machining and shaping the graphite to very exact specifications. After the graphite is soaked in water and the bare anodes are placed in plating cells through which Lead Nitrate electrolyte circulates. A small amount of nitric acid in the electrolyte improves coverage.
During the plating the current denisty is varied according to a very exact specification. Higher current densities are supplied at the beginning then amperage is reduced. Seven hour depositon time.
_________________________________________________________

If the professionals were plagued with problems, what about the rest of us.
The GSLD Anode are not simple either. I would think Pacific
Engineering had more time and cash than myself..... here I go again..............:-)
Perhaps the Ti substrate will prove to be of similar fickle nature.


I'm SFTMFTATSFK. (Spending Far Too Much Fucking Time At This Stupid Fucking Keyboard :-))

If massive anode were so simple lots of us would have a massive anode in our Chlorate cells when the substrate was eaten away.
Fineto

I wonder what the big Perchlorate manufacturers are using nowadays for Perchlorate manufacture?

Short, terse answers ONLY, thank you. PC incorrect 'eyes rolling icon' here.

Dann2

Rosco Bodine - 10-6-2007 at 11:59

@ Alan

Quote:
Originally posted by alancj
I was thinking that the surest way to control pH (and therefore lead ion concentration) would be to use a pH probe in the plating tank, and interface that with a microcontroller to drive a small agar to deliver salts to an addition tank, which is circulated with the plating tank. (oddly enough, I live a half mile away from a company that manufactures agars for pellet stoves!) Maybe just knowing the plating deposition rate one could do it without automatic feedback, and skip the probe. I think that is what you'd have to do with an acidic plating bath at least.

Great minds think alike ! I have been wondering if there is a
pH color indicator which would endure the conditions to provide a visual monitoring of the pH of the electrolyte .
The idea of using a pH probe and an automatic controller like is used for the pH control in hydroponics also has been in my mind . But instead of an auger , you just output the controller to a small motor driven globe valve which increases
or decreases the proportion of diverted flow from your circulator pump to the "percolator funnel" in order to provide
a variable pH up function , while the ongoing electrolysis provides a steady pH down function that is being balanced at any desired pH which is programmed as a setpoint for the controller regulator . So long as the volume and temperature of the electrolyte is held pretty constant , not allowed evaporation loss for example , a simple bath conductivity sensor reading might be a good indicator
of pH without having to use an actual pH probe . Two lead plates with a low regulated DC voltage across them like 0.7 volts and a current monitor to babysit , might be a workable
pH monitor for input to an op amp regulator setup .
Quote:

For a neutral one I think a percolation funnel would be fine, like Rosco mentioned. IMO it would be pretty hit or miss trying to get a lead compound with the right properties so as to dissolve at the exact rate you want at the exact pH etc., in anything but a neutral plating bath. -Alan

Yeah , the choice of lead basic salt used would automatically
choose the equilibrium pH for you , and concentration of the
bath would always be near saturation , unless you were manually manipulating it . The scheme for a percolation funnel can actually be run in reverse as a fluidized bed ,
like what a sand filter would be doing when being flushed
for cleaning . I didn't want to complicate things by going
into that , but it is really the best way to use that sort of technique as it stirs and churns the neutralizing particles
in suspension , greatly increasing the efficiency of the
neutralizer .

@ hashashan

Quote:
Originally posted by hashashan
There goes an interesting question :
If we do hang something like a tea bag of lead carbonate(or any other lead compund that will react with HNO3) what will happen? will the trace amounts of HNO3 forming will react immediately with the lead compund hence making a neutral bath. Or because of no movement in the tank the only reaction will be caused by drifting of the solutions and making quite stable acidic PH?


What I was saying there is it would be better than nothing
to have a teabag sort of neutralizer in a one tank simplified setup , if any sort of pH control of the crudest sort is acceptable . But really a pumped system is the best way to go , and you can control the rate of the neutralizing somewhat simply by diverting more or less of the recirculated
flow to or away from going through the neutralizer .

@dann2

The method of US4064035 supposedly eliminates that need for a curved surface substrate which matches the natural
curvature of the deposit of PbO2 . US2859166 uses a
shielding method which also eliminates that curling effect .



[Edited on 10-6-2007 by Rosco Bodine]

jpsmith123 - 10-6-2007 at 14:01

Quote:
Originally posted by dann2
[...]
I wonder what the big Perchlorate manufacturers are using nowadays for Perchlorate manufacture?
[...]


The only things I've ever seen offered for sale for perchlorate manufacture are: 1) Platinum over titanium, and 2) PbO2 over titanium.

Platinized titanium mesh anode
Platinum plated titanium plate anode
Platinum cladded titanium anode
Lead dioxide coated titanium mesh anode
Lead dioxide coated titanium box anode
Lead dioxide coated single stem titanium box anode
Lead dioxide coated double stem titanium box anode

http://www.titanindia.com/potassium%20perchlorate%20cell%20a...

BTW Dann2, have you ever tried the in situ oxidation of a lead plate? IOW, mount a piece of lead in a cell, add a dilute H2SO4 solution, anodize to build up a thin layer of PbO2, then without touching the anode, drain the H2SO4, fill with NaClO3 solution, and electrolyze.

I'm thinking that if the electrodes in the original Plante cell were made that way, maybe they're rugged enough to work at least a few times in a ClO4 cell.

dann2 - 10-6-2007 at 14:50

Hello,

Never tried the Lead Plate in H2SO4 idea.

Will the deposit be non porous and adherent is the question. It would not be a very expensive thing to try out.
What conc. of Sulphuric would you recommend.

There was a process mentioned on this board for making Chlorate (and Perchlorat??) using Lead Bars. It was some Government sponsored project from years ago. I never seen or read it. Do you know where it is. Perhaps it might point the direction of where/what you need to do with a Lead Anode. It would be a toxic product IMHO. Handling(dilute) soluble Lead Compounds in the product.

Regarding the Valve metals..........

I connected my selection (!) of Valve metals to a power supply (DC). The electrolyte consisted mainly of Na Chlorate, some Perchlorate and a few % Chloride.

Ti was struggling at 23 volts and broke down at about 25/26 volts. The Ti is Grade one.

Ta was OK all the way up to 45 volts, the max. of my power supply. The Ta is pure.

W was OK all the way up to 45 volts, which was surprising. I tried two pieces of W as I had suspected that the flat sheet I had purchased on Ebay (some time ago) was not W. So I also tried a TIG welding electrode which is W. It too was OK all the way up to 45 volts.
This is surprising. The flat sheet is pure, I don't know about the TIG welding piece but I think it is pure sintered W.

I also tried Al. It was pure Al (Analythical reagent granuals). I got the biggest piece I could get. It was hopeless with no 'Valve' quality at all. I seen Al listed as a Valve metal once.

W TIG welding rods are available at all welding shops for a dollar or two. I wonder would they do instead to Ti. Perhaps the DTO (Doped Tin Oxide) would not dissolve with/into the W Oxide.
I guess it would be wise to keep with Ti for the moment.

When the metals were put into the electrolyte a surge of current flowed which then dwindled to zero. Got some pretty colours too.

I am in the process of calibrating my thermocouple thermometer. A thermocouple wire + voltmeter.
Do any of you guys know of an alloy that will melt at 450 to 480C (approx) This is the temp. for baking the DTO on Ti. I do not think it is wise to go above 500C because of the transition of Ti oxide. It undergoes a volume change.

I have already melted Lead and Zinc. Perhaps theses two data points will do me.
Too stingy to purchase a proper thermometer.
500C is described as 'grey' heat when viewed from the point of view of colour.

It is a high tech oven. Floor tiles in a coffin shape about 6 by 6 by 30 cm held together my copper wire and surrounded by perlite (volcanic rock from a garden shop) all in a tin box.

Heater is a Nichrome spiral connected to a variac.

I will be using Stannous Chloride and Ammonium Molybdnate.
Most of the patents call for Stannic Chloride + Antimony Chloride. But a patent on my site give a list of compounds and theses were included.
Will Stannous Chloride do, do ya think??

It is available on ebay + the Ammonium Moly.

DANN2

gilbert pinkston - 10-6-2007 at 15:07

MadHatter

International Hazard




--------------------------------------------------------------------------------



Posts: 809
Registered:
Location: Mid-Atlantic
Member Is Offline

Mood: Patience growing thin !
posted on at 01:36 AM

KClO4



gilbert pinkston, I've already made plenty of potassium perchlorate without
problems. As for indigo carmine, I have enough of that for a long time. Found
50 grams on eBay for $25. Not bad considering the higher prices I've seen
elsewhere on the net. My last batch of KClO4 was about 8 LBS. Very nice,
flat rhombic crystals in contrast to the KClO3's cactus needles which are
produced 1st during the electrolysis. BTW, I should have mentioned in 1 of
the earlier posts that the indigo carmine test can detect chlorates down
to 1 ppm. The test is sensitive enough to ensure that there shouldn't be
any problems when making NH4ClO4.
--------------------------------------------------------------------------------------------

this is from an earlier post MadHatter seems to have made perchlorate at will what is all this talk why not use his method?
by the way what was his method?

Rosco Bodine - 10-6-2007 at 15:34

A Schottky diode structure is what is being implemented
with the valve metal and semiconductor oxide laminate .

http://en.wikipedia.org/wiki/Schottky_diode

It may be that there are electrolytic methods involving different valve metal combinations which are detailed in
semiconductor literature , as this would be likely to have been the subject of more research for the electronics applications , than for "off label" use as anodes .
Various dopants and methods for lowering the reverse breakdown voltage to essentially have an ohmic semiconductor layer over the metal substrate may already be extensively described in the literature where
the various combinations were (hopefully) the source of experiments in rectifier design . Whatever dopants
were the most counterproductive for the reverse breakdown voltage parameter of the diode are precisely
the dopants which would be of interest for the anode
application .

[Edited on 18-6-2007 by Rosco Bodine]

In Situ PbO2 coating on Pb

jpsmith123 - 10-6-2007 at 15:46

The following procedure is from a page dealing with chrome plating.

################################

ANODES

These are made of lead strips. Various sources can be found, but the material I use is about 1/8" (3.175 mm) thick cut or formed into the required shapes from a 4" (101.6 mm) waste pipe section available from plumbing/hardware stores. Joiner sections can be bought about 8" (203.2 mm) long.

Lead is attacked by chromic acid and an insulating layer of lead chromate (yellow in colour) will be formed if the anodes are not first treated. This lead chromate interferes with the plating current flow, but is easily avoided by transforming the working surface of our anodes into lead peroxide. The oxide prevents the formation of lead chromate, whilst allowing the passage of our plating current.

4.1 PEROXIDING THE ANODES

NOTE: For current density required for this treatment, the current is 5A/sq ft. (0. 035A/sq. in., or 0.55A/DM2) of total wetted anode areas.

Make up a 5% solution of sulphuric acid in water
Clean by scraping the lead anodes
Connect two of these lead anodes to the DC power supply, one positive, one negative
Adjust the current density to 5 A and maintain this for 15 minutes
Reverse the polarity of the DC supply and maintain 5 A for 15 minutes
Finally, reverse the polarity of the DC supply one more time and maintain 5 A for another 20 minutes

A dark brown coating on the anodes will indicate the presence of our protective layer of lead peroxide. Dry the prepared anodes and put them aside, ready for use. This process will be repeated on any anodes which tend to develop yellow spots during use (because of the lack of the lead peroxide coating).

http://freepages.pavilion.net/users/nickfull/chrome.htm

PbO2 Plating

MadHatter - 11-6-2007 at 14:21

Jp, where did you find this ? I'll have to try this out. If this works more easily than the
lead nitrate plating bath then our perchlorate production problems may be solved.
I've had bad luck plating carbon/graphite rods with PbO2 because they're extremely
fragile.

jpsmith123 - 11-6-2007 at 15:17

Hello MadHatter,

I came across that article while I was trying to find out how the original lead acid cells were made by Gaston Plante.
I'm still trying to find that information.

I did find the following references...now if only someone could get the full text papers.

http://www.osti.gov/energycitations/product.biblio.jsp?query...

http://www.osti.gov/energycitations/product.biblio.jsp?query...

hashashan - 11-6-2007 at 22:11

But isnt that in the beta form? we need the alpha.
IIRC the PbO2 on the lead will be brown and fluffy, and it will just flake off as soon as we start electrolizing the NaCl solution.

alancj - 12-6-2007 at 02:09

I think you have it backwards. Beta is the form we want for anodes.

jpsmith123 - 12-6-2007 at 02:23

As I understand it, it mostly beta when formed in this manner.

In any case, it seems to me the PbO2 coating must be somewhat robust, or it wouldn't have worked in Plante's cell, nor in the chrome plating application mentioned here.

Maybe someone can give it a quick try and report back?

hashashan - 12-6-2007 at 02:34

ok so i meant the other way around. That doesnt really matter, its still a different form. And such a form that is made wit this method i no good for us.

jpsmith123 - 12-6-2007 at 03:17

How do you know it won't work? Or have you tried it or some similar process? You may be right, I don't know. Understand, all I'm talking about is finding a quick and dirty way to make a few lbs of perchlorate...I'm not talking about making some rugged, long lasting, state-of-the-art anode.

hashashan - 12-6-2007 at 03:34

i didnt try it. I just dont believe itll work because there is no way that the PbO2 remain on the anode.
I would be glad to know if anyone tried that

dann2 - 12-6-2007 at 10:06

Quote:
Originally posted by jpsmith123
As I understand it, it mostly beta when formed in this manner.

In any case, it seems to me the PbO2 coating must be somewhat robust, or it wouldn't have worked in Plante's cell, nor in the chrome plating application mentioned here.

Maybe someone can give it a quick try and report back?


What is the Plante's cell. I USFSF but could find nothing.

Regarding Alpha and Beta.
The Beta seems to be the one industry goes for. It is better wearing than Alpha. Alpha seems to stick better to things so that is why it will be recommended as a first coat.
Some patents/articals use both claiming both together give less stress------> less crcking.
The Beta has a higher overvoltage for Oxygen giving more efficient production but nothing that would be any great advantage to us.
I'll take either if they work.!

Dann2

jpsmith123 - 12-6-2007 at 13:42

Well, if it was as fragile as you suggest, then I find it hard to believe that it was used in the original lead-acid cell. Don't forget, we're not talking about about a thick coating here.

BTW, as I understand it, alpha PbO2 is what you'd like to form first, and then beta over it. So maybe begin the process with a relatively high pH and then lower it? I don't know...it seems like it would be worth experimenting with this a little bit.

Quote:
Originally posted by hashashan
i didnt try it. I just dont believe itll work because there is no way that the PbO2 remain on the anode.
I would be glad to know if anyone tried that

hashashan - 12-6-2007 at 23:44

Hi, I started another batch of perch with my old PbO2 anodes. Now i know that the curr.density for those should be 150-400 mA/cm^2 but are there any limitations on the cathodes? (i use graphite cathodes)

Rosco Bodine - 13-6-2007 at 00:45

Quote:
Originally posted by jpsmith123
BTW, as I understand it, alpha PbO2 is what you'd like to form first, and then beta over it. So maybe begin the process with a relatively high pH and then lower it? I don't know...it seems like it would be worth experimenting with this a little bit.


Something worth experimenting with would be a combined
PbO2 plating bath containing a mixture of lead acetate and lead nitrate , and operated at a very mildly acidic pH , perhaps pH 5.3 . The patent US4064035 teaches the
application of sequential layers of alpha and then beta lead
dioxide , but the process interrupts the plating between layers which uses different plating baths for each allotrope ,
rinsing off the alkaline residue from the alpha plating bath ,
and transferring the electrode to a nitrate bath for the
resumed plating to deposit the beta layer .....and so on ,
the interruption of plating likely producing a boundary layer
where a delamination could occur at the interface beween the differing strata .

If you look at the plating conditions in the Union Carbide patent US3033908 (attached) , it describes a plating of alpha PbO2 from a slightly acidic lead acetate bath at about a 20% electrolyte concentration and a current density of 35-50A sq. ft . And if you look at the JES Bromate Cell article
http://www.sciencemadness.org/talk/viewthread.php?action=att...
where the anode preparation is described , at a similar pH and concentration of electrolyte and current density which is
identical , except that lead nitrate is used to deposit the
beta PbO2 ......it is reasonable to conclude that likely
a coelectrodeposition of alpha and beta PbO2 is possible from a mixed lead acetate and lead nitrate electrolyte .
Hopefully the mixed forms of PbO2 deposited would form an internally stress relieved deposit which would plate out evenly without any tendency to curling , as the product of
an uninterrupted plating which would have greater mechanical strength and stability . I can find nothing about this in the literature but it would seem to be a highly logical next experiment with regards to the massive PbO2 anode .
This technique if it works might have value for improving heavy coatings of PbO2 which are applied to any sort of substrate also .

The only complication which I have anticipated is that the potential may be slightly different for the plating out of one form or the other , and it may require a waveform of varying DC to accomplish a smooth mixture ....something like a rectified AC of an appropriate voltage without regulation and filtering could work better for this than a regulated DC supply .

[Edited on 13-6-2007 by Rosco Bodine]

Attachment: US3033908 alpha LEAD_DIOXIDE from lead acetate and sodium nitrate plating bath.pdf (136kB)
This file has been downloaded 822 times


Cathode current density

dann2 - 13-6-2007 at 14:52

Quote:
Originally posted by hashashan
Hi, I started another batch of perch with my old PbO2 anodes. Now i know that the curr.density for those should be 150-400 mA/cm^2 but are there any limitations on the cathodes? (i use graphite cathodes)


Hello Hashashan,

I am not aware of any magical number for current density on Cathodes.
Once the figure is sensible, with a cathode each side of the anode and of similar size to keep current distribution on the Anode fairly even, it will be OK.

Dann2

Etching Ti with Oxalic acid.

dann2 - 14-6-2007 at 13:11

Hello,

When etching a Ti strip I added 60 grams Oxalic acid to 700 ml water. This etched the first strip of Ti OK. The solution turned an orange colour.
When I reheated the solution the next day it turned clear. I added another strip of Ti but it would not etch. I added a further 60 grams Oxalic acid and it still would not etch the Ti. (similar Ti as before)
Anyone know why??
The solution is at 80 to 90C.

Dann2

Stannous Chloride + Ammonium Molybdnate

dann2 - 14-6-2007 at 13:14

Hello,

Got around to trying some Doped Tin Oxide on Ti. The procedure I followed is similar to Pat. No. 3940323.
_______________________________


EXAMPLE 1

A strip of titanium plate is prepared by immersion in hot oxalic acid for several hours to etch the surface, then washed and dried. A solution of 2.2 parts of SnCl4 5H2 O and 0.2 parts of (NH4)2 MoO4 in 5 parts of water is brushed on to the cleaned titanium surface. The coating is dried by heating at 100.degree.C for about 2 minutes than heated in an oven with a forced flow of air at 400.degree.C for about 5 minutes to convert the coating substantially to the oxide form. The process is repeated three times with a final heating in air at 400.degree.C for 30 minutes
_______________________________________
The above patent is for a DSA but I am just using the DTO part of the Patent. Then going to plate Lead Dioxide.

I used Stannous Chloride (SnCl2) instead of Stannic Chloride as above.
The patent names Stannous Chloride as a compound you could use.
When I mixed the Stannous Chloride with the Ammonium Molybdnate I get a dark green precipitate. I ended up painting on a suspension as opposed to a solution.
What would you expext to get when you add Stannous Chloride to Ammonium Molybdnate? Does a dark green ppt make sence does anyone know.
What ions do you get when you dissolve Ammonium Molybdnate.
I am also not 100% sure of the purity of the chemicals.

Cheers,
Dann2

12AX7 - 14-6-2007 at 16:20

Molybdate(VI) reduced by Sn(II)?

In Situ PbO2 plating

Xenoid - 14-6-2007 at 20:39

Greetings all!

I just had a go at the in situ PbO2 plating, with little success!

1mm thick Pb sheet was used to make electrodes 11cm by 6cm. The plating was carried out as described in the above procedure; 5% H2SO4 and current of 5.5 mA/cm2
I added an extra strip/coat step and extended the final coat time to twice that suggested.

I used some of my residual chlorate/chloride mother liquor and a Ti cathode to test the PbO2 coated anode. As soon as the current (1-3 A) was turned on, I was greeted with a myriad of white PbCl2 spots on the anode which grew larger and more voluminous with time!

I'll try stripping it again and give it a really thick coat, but I'm not very optimistic!

Regards, Xenoid

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