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Author: Subject: More on PbO2 electrodes
MadHatter
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[*] posted on 11-3-2006 at 21:54
ClO4


SAM4CH, I also found that NaF increases the efficiency of the cell. Dichromates and persulphates
work well although dichromates won't help PbO2 rods. Sorry it took so long to get back to this
thread. BTW, congratulations on your yields !

Jpsmith123, I connected the power supply to the graphite - not the PbO2. The PbO2 layer is
too fragile for my clamps.




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jpsmith123
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[*] posted on 12-3-2006 at 01:31


SAM4CH, did you boil and then cool the cell liquor to get the NaClO4 out, or did you add KCl and precipitate out KClO4 and then calculate your equivalent NaClO4 yield?

Also, you're saying, all the PbO2 anodes you made cracked?
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SAM4CH
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[*] posted on 12-3-2006 at 03:45


No, I recrystalized NaClO4 after add few milliliter of HCl to destroy any chlorate remain and then I boiedl the solution and collected the moisture crystals.
I said PbO2 anode was cracked through electrolysis for more than one electrolyte, e.g. I faced cracking at first electrolyte for one of my anodes, and after 2nd or 3th electrolyte all of my anodes was cracked.
Note: every electrolyte take about 4-5 days.




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SAM4CH
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[*] posted on 5-5-2006 at 14:48
PbO2 on Steel!!


I'd like to ask about the typical bath for deposition PbO2 on stainless Steel?

and what about making perchlorate with no corrision of lead dioxide electrode within few weeks?!!
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SAM4CH
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[*] posted on 6-5-2006 at 16:06


What about fluorine modified lead dioxide!!?



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st0ne
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[*] posted on 30-6-2006 at 05:28


Several days ago my PbO2 anode was complete. I used the method described here: http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
My plastic substrate is covered with 1mm black PbO2 layer. Its surface is 220 cm^2 but 50 cm^2 are useless because they are conected to two graphite plates which carry the current.
Yesterday I started my chlorate cell with this anode, mild steel cathode and 5V/5A power supply. At the beginning everthing was ok. The current was 3.5A and I left the cell for several hours. When I came back the current was less than 1A. It was 0.08A. I checked everything: power supply, cables, the cathode and the anode. And it seems that the resistance of the anode now is very high. I washed it with water and recreated all connections but with no effect. I really don't know what happened with my anode. I use table salt and tape water. May be this the problem?
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[*] posted on 30-6-2006 at 13:13


Don't you need a persulfate or fluoride additive to go with PbO2? (I recall chromates don't work.)

Tim




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[*] posted on 30-6-2006 at 13:38


Persulfates and fluorides increase the current because it gets lower and lower over time but it doesn't change so fast. From 3.5A to 0.08A in less than 10 hours. And it was so low even in a brand new NaCl solution. In my view something happend with the anode but I don't know what.
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[*] posted on 30-6-2006 at 19:40


Yeah no doubt. Seems to me the connection is bad...perhaps the PbO2 layer is fractured, perhaps at the electrolyte level say?

Tim




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[*] posted on 1-7-2006 at 03:18


I didn't see any cracks but maybe you are right. I will put the anode in the plating solution for several hours to fill any possible cracks.
And is the temperature of the plating solution very important? I ask because I didn't maintain it very well. It was between 20 and 50 centigrade.

[Edited on 1-7-2006 by st0ne]
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Rosco Bodine
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[*] posted on 14-9-2006 at 09:30


Something which could be worth looking at is the
lead oxychloride materials . I have no idea what
if any may be the usefulness for an electrode or a
substrate , or even if it is conductive , but it would
seem likely that it would be .

I have not looked into this at all , but it could be that
these lead oxychloride compositions may be formed
similarly as are the better known zinc oxychloride cements . There may be some mixture of lead oxides
and lead chloride which could be heated together to
a melt or a fusion and reaction point , which would set up
to an oxychloride cemented composition having usefulness .

Also there is a reaction between glycerine and lead monoxide which is known to form a self-setting cement ,
and this may have some usefulness as a binder or substrate .

Some alloyed perhaps eutectic fusion mixtures of lead chloride , lead chromate , lead phosphate , and lead sulfate in mixture with lead oxides could might also have usefulness as an electrode or a substrate . What I am thinking here is along the lines of something like a ceramic which is formed entirely from lead based compounds . Possibly also a cold formed mixture of these materials could be found useful , something which would mix together as a paste and then set up from reaction , as a cement .

The following page contains a bit of information on the
oxides and oxychlorides .

http://www.1911encyclopedia.org/Lead


[Edited on 14-9-2006 by Rosco Bodine]
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[*] posted on 14-9-2006 at 15:58


Adhesive backed Velcro is another material which might have usefulness in some arrangement as a substrate upon which to apply a paste of PbO2 . What I am thinking here is that when secured to a rigid backing like
polycarbonate or plexiglass , perhaps using additional adhesive like a polyurethane varnish painted on the backing and dried till it has a very firm stickiness , that
it should be dimensionally stable after it hardens and cures completely . The open loop texture of the velcro should secuely hold and reenforce the paste rubbed into that textured substrate , and then additional material could be electroplated onto it . Possibly there could even be uses where the lead dioxide paste could be sandwiched in the middle between mated reenfoced velcro substrates like a PbO2 sandwich .

Is nylon attacked in a perchorate cell ?
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[*] posted on 14-9-2006 at 19:36


Some lead oxychloride containing other oxides form glasses that seem to be conductive, no idea what the physical attributes are.

http://www.iop.org/EJ/abstract/0953-8984/6/31/018

http://www.iop.org/EJ/abstract/0953-8984/11/41/304
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Rosco Bodine
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[*] posted on 14-9-2006 at 21:11


One of the lead oxychloride molten glass compositions is used to fill fissures in flawed diamonds to improve their cosmetic appearance . So evidently it will stick to carbon of the diamond variety , so there's a chance it might stick to graphite or amorphous carbon as well , and could possibly make a good bonding and sealing layer on carbon or graphite for later plating of PbO2 . The melting point is relatively low for that oxychloride used on diamonds and I have no idea what its electrical property
is , or what is the formula ....probably a trade secret .
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Rosco Bodine
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[*] posted on 15-9-2006 at 10:57


Another idea for a substrate is those perforated epoxy and fiberglass prototyping circuit boards having the holes on 1/10 inch centers , used as a stiff backing for
a thick filter paper blotter or felt or mat or batting material , which could be used as an absorbent for
either a paste of PbO2 physically rollered into the
absorbent mat , or used to absorb Pb(NO3)2 , which
is later chemically converted to precipitate the PbO2
trapped in the absorbent material . Cut lengths of
solid braided rope or cordage lashed to the perfboard
might also make a useful absorbent .

The absorbent felt could be secured to the proto board
backing by lacing it down with fluropolymer fishing line
and a sailmakers sewing needle , using the holes around
the perimeter as anchorage and securing it with parallel
lines as if it was a 1/10 inch mesh window screen being
sewn , adding any loops where desired to firm cinch down the absorbent mat to the perf board backing .

If proto board and filter blotter doesn't hold up to the conditions in the electrolyte , then teflon sheet and fiberglass mat or heavy fiberglass cloth could be substituted .

Another idea for using solid braided cordage or rope as an absorbent substrate is to bring one end through the bore of a teflon tube and begin to wind a tight spiral
around the outside of the tube to its top . Woven fiberglass ribbon or hollow braided sleeve could be used in a similar way .

Another thought .....

Perhaps adding some diatomaceous earth and/or chopped glass whiskers , and or grog to the PbO2
paste used for massive PbO2 anodes which are pressed damp and then baked or fired to cure , would give some
added strength to the finished article .

For a commercial application , there is an idea which
I have had concerning the massive PbO2 electrode . It involves the use of a solid teflon or other
suitable plastic threaded rod as a core substrate ,
but the thread is a dovetail groove spiral routered using a high speed dental bur . The PbO2 paste would then
be securely held by the spiral dovetail groove cut into
the surface of the substrate . Alternately , an Acme
thread , having additional longitudinal parallel spline cuts which have the dovetail profile could work , or simply using lengthwise dovetail spline grooves alone might suffice to provide a mechanical anchorage for the PbO2 paste . The idea is to provide keystone shaped protrusions rising from the substrate which are wider at
their free ends , so that they act as retainers dovetailed
into the PbO2 layer , securing it firmly to the substrate .
A cylindrical anode made this way could then have
an open mesh screen further wrapped around the
outside , and the PbO2 would be so well secured
that it wouldn't be going anywhere anytime soon .
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Rosco Bodine
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[*] posted on 18-9-2006 at 20:07


I have found what may be the easiest idea yet for for a porous ceramic substrate for PbO2 anodes .

Those sintered ceramic airstones which are used for
aeration of the water in aquariums look like a good candidate .

Here's a couple of links .

http://www.marinedepot.com/md_viewItem.asp?idproduct=AP7255

http://www.wonbrothers.com/product/airstone/airstone.htm

The flat type is interesting also .



[Edited on 19-9-2006 by Rosco Bodine]
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[*] posted on 13-1-2007 at 22:47


*BUMP*

How about using carbon fiber cloth as a substrate?
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[*] posted on 26-1-2007 at 15:35


Rosco,

Did you ever get a chance to try impregnating air stones? With the availability/price of perchlorate quickly becoming an issue, this might be a great time to revive the topic.

I just picked up a 12" Sal Chlor anode from the Direct Pool Supplies company in Australia. With postage, it worked out to ~US$85. When it arrives in a week or so, I'm going make a few runs and I'll report back.
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[*] posted on 27-1-2007 at 06:05
A better preparation of a lead dioxide anode


I found a side which explains the preparation of a lead dioxide anode by oxidiseing lead of the surface of a graphite rod.

The autor wrote that these anods hadn´t a realy long live because of the wear.
Sorry, I kan´t find the page any more.

I have another idea to produce such a anode with maybe a longer live.
I would oxidise a lead rod with maybe a NaOH solution as anode, it should make PbO2 on the surface which should be stronger against wear because it´s bandaged with the lead in the centre and not just with graphite.

But I´m not sure if these methode would be successfull, what do you think about it?


Sorry for my english I hope you understand me, maybe 100 posts later it would be acceptable.
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[*] posted on 27-1-2007 at 17:10


Maybe, PbO2 is unstable in NaOH solution.
"Lead dioxide dissolves in alkali hydroxide solutions to form the corresponding plumbates.

PbO2 + 2 OH– + 2 H2O → Pb(OH)62–

[Pauling, Linus General Chemistry, W.H. Freeman 1947 ed.]

I don't know much. What work do you perpare it for?
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[*] posted on 27-1-2007 at 18:36


Hello Folks,

It is good to see a discussion of this 'old chestnut', ie. Anode
making etc. I'm the guy who has spent far too long in his
garage (as someone here said)!
Back in 99 I put up the page on Chlorates and Perchlorates on 'Yahoo-GeoCities'. It is good to see people are reading the info. I put up the page after alot of discussion with other folks at the time. Most of the page is really a collection of other peoples work but I have spent some time myself making Anodes and (Per)Chlorates and diging out articals from Libraries and the net. The ultimate goal was to be able to make a simply rugged Anode from easily obtainable materials. Me thinks there is still some work to be done.
I think it is fair to say that the Lead Dioxide Anode is still
an elusive beast. It is realitively easy to make an Anode but to make one that willl last for a long time in the (Per)Chlorate cell is another matter. Then there is the matter of all thoses horrible toxic Lead compounds...
I managed to make a ceramic substrate Lead Dioxide Anode that lasted for 3 months in a cell 24/7. It was (alas) a one hit wonder, I could never repeat this. Some Anodes I made since only lasted 10 minutes:mad:
It would be nice if one could make a non toxic Anode like Magnetite or Manganese Dioxide.
There is nothing wrong with using Graphite to make Chlorate, in fack I thing it is oftern forgotton in the rush to reach the 'holy grail' (as someone here put it) of the Lead Dioxide Anode.
If using Graphite, keep solution temp. low (use large vessel), keep current density low, keep Chloride concentration high, too hell with current effeciency. It is better IMO to have a long lasting Anode and to take your time.
It would be nice to experiment with using Graphite to make Perchlorate using pure Chlorate (no Chloride) to see what wear rates on the Anode are like. I have never done this. Always assumes you simply could not get Perchlorate using Graphite.
Magnetite I have used to make Chlorate. It was a rugged Anode that was impossible to wear out even at very high current densities. The Anode was make with a blow torch and ceramic store Black Magnetic Oxide.
Some guy here suggested getting a magnet the shape of a bar, sticking the stuff to it (it will stick itself) and seeing what happened. Seems too good to be true but you never know.
I have also make a magnetite Anode of sorts using a oxy-fuel blow torch and a rod of mild steel, but never got around to trying it out. (shame on me)

I will start this crusade again.............. Hopefully I will get out of the garage at least once a month (for 10 minutes or so!).

Dann

http://www.geocities.com/CapeCanaveral/Campus/5361/basechem....
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[*] posted on 29-1-2007 at 08:01


Hello Dann!

Your website has been an invaluable resource for many who are looking to make lead dioxide anodes. Thanks for making all of that great information and notes of your experiments available. :-)

[Edited on 29-1-2007 by FrankRizzo]
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[*] posted on 31-1-2007 at 19:36


Quote:
Originally posted by FrankRizzo
Hello Dann!

Your website has been an invaluable resource for many who are looking to make lead dioxide anodes. Thanks for making all of that great information and notes of your experiments available. :-)

[Edited on 29-1-2007 by FrankRizzo]



Good to see the site is of use.

I have put some more articles in the further reading section.
Someone here was looking for some of them, I cannot find the original post/name, appologies.

They are JES August 1961, July 1957 and March 1958.

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

I am attempting to construct a kiln of some sort (small) to melt Magnetite or sinter it. There is Kanthal wire being sold on ebay. This stuff goes to 1400C. This is at or above sintering temperature.
Could try gouging rods as elements. Carbon can go way above the melting temperature fo Magnetite.

Any ideas or pointers for home constructed furnaces.

Dann2 (formally Dann)
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[*] posted on 31-1-2007 at 21:56


Quote:
Originally posted by FrankRizzo
Rosco,

Did you ever get a chance to try impregnating air stones?


No , but I wish I had more time for experiments because I have a backlog of ideas that need testing :D Anybody feel free to run with any of those ideas that seem like they are worthwhile .

I did get some 3/4" by 14" gouging rods for future use .

And I spent about a month pouring over two dozen pages of schematics and data sheets to come up with what looks like a valid circuit for adapting a computer power supply to a decent precision 40+A regulated laboratory supply .

Every time I think a little project will take an afternoon .....
and soon discover it's not as simple as I first figured , I get
determined not to let it get the better of me ....and then a week or two later cringe and ask myself just what in the hell have I gotten myself into :D But it seems like the damn bureaucrat regulators are always coming up with something new , and as a consequence I seem to stay busy at formulating countermeasures .

Quote:

With the availability/price of perchlorate quickly becoming an issue, this might be a great time to revive the topic.


Yeah , and not just perchlorate ...there's a lot of interesting things you can make using electrolysis .

Quote:

I just picked up a 12" Sal Chlor anode from the Direct Pool Supplies company in Australia. With postage, it worked out to ~US$85. When it arrives in a week or so, I'm going make a few runs and I'll report back.


Yeah ...let us know .
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[*] posted on 2-2-2007 at 08:02


Quote:
Originally posted by dann2
I have put some more articles in the further reading section.
Someone here was looking for some of them, I cannot find the original post/name, appologies.

They are JES August 1961, July 1957 and March 1958.

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


That was I looking for those articles. Thanks for posting them up on your page for everyone to access. Someone in the references thread (Solo, I believe) had access to them, and graciously uploaded them for me as well. Although the ideas in them are definitely aimed more toward industrial processes, they're nice reference material.
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