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Author: Subject: Thoughts On Anodes
dann2
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[*] posted on 6-8-2011 at 05:41



Perhaps it's time to invest or make a high temp. oven/furnace.
The homemade oven I have would only go up to 800C (or so I suppose). It's a very crude affair but good for 500C or so for making Tin Oxide, MnO2 etc on Ti Anodes.
It does not even have temp. controll just a variac on input element.

Dann2
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jpsmith123
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[*] posted on 6-8-2011 at 10:03


Well if the stuff works you could probably get your money back (and then some) selling perchlorate anodes on ebay.

BTW here's an abstract of a paper that claims a method to make bismuth tin pyrochlore at 873 degrees K (600 C).

http://www.sciencedirect.com/science/article/pii/S0167577X99...

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

I was looking into bismuth tin pyrochlore and I happened to come across the following (which I also requested in the "wanted references" section):


Distinctive Tin Dioxide Anode Fabricated by Pulse Electrodeposition: High Oxygen Evolution Potential and Efficient Electrochemical Degradation of Fluorobenzene

Tao Wu, Guohua Zhao*, Yanzhu Lei, and Peiqiang Li
Department of Chemistry, Tongji University, Shanghai 200092, China

J. Phys. Chem. C, 2011, 115 (10), pp 3888–3898
DOI: 10.1021/jp110149v
Publication Date (Web): February 21, 2011

Abstract
A distinctive Sb-doped SnO2 anode with a high oxygen evolution potential, 2.4 V vs the saturated calomel electrode, and a strong electrochemical oxidation ability was prepared on TiO2 nanotubes through the pulse electrodeposition method. Compared with the traditional Sb-doped SnO2 electrode prepared by the sol−gel method, the proposed SnO2 electrode has a higher crystallinity, a higher order degree of the atomic lattice, and a lower concentration of oxygen vacancies. The scanning electron microscopy image confirms that the surface of the electrode presents a three-dimensional structure consisting of Sb-doped SnO2 nanoparticles with a certain microspherical structure, which increases the specific area greatly and provides more active sites. The reaction activation energy also decreases from 11.67 kJ mol−1 for the traditional SnO2 electrode to 5.73 kJ mol−1. This SnO2 electrode is demonstrated to have a superior electrochemical oxidation ability for refractory fluorobenzene, which is extremely stable and cannot even be degraded effectively on a boron-doped diamond electrode with a strong oxidation capacity. The results also indicate that the distinctive SnO2 electrode has a higher apparent rate constant, total organic carbon removal, and mineralization current efficiency, which are 12, 2.6, and 3.3 times those of the traditional SnO2 electrode, respectively. The evolution of intermediates and the degradation mechanism of fluorobenzene were further discussed. This study provides a distinctive SnO2 anode for the effective electrochemical oxidation of refractory toxic organic pollutants.


[Edited on 6-8-2011 by jpsmith123]
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jpsmith123
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[*] posted on 7-8-2011 at 10:33


Well Solo came through as always with the paper I asked for, but unfortunately it's partly written in "Chinglish"...just like the documentation you would expect to get with any new piece of Chinese manufactured computer hardware.

Apparently the authors attribute the excellent performance of their anode in part due to the TiO2 nanotubes and in part due to their method of electrodeposition of the Sb doped SnO2.

This paper is interesting to me in part because, unless I missed something in the text, the anode is apparently ready to use just as it comes out of the plating tank, whereas other papers I've seen on electrodeposited SnO2 describe a high temperature annealing step which enhances the crystal structure and makes the material more durable.

Anyway, what I was specifically interested in, in this paper, was the details of how they went about directly electrodepositing Sb doped SnO2...as it might be a generally useful method workable with other substrates and other dopants.

To that end I've read the relevant part of the text about three times, and I still don't fully understand their process. Unfortunately, not only is their method very imprecisely described (e.g., "a certain concentration of hydrochloric acid"; LOL!) but the text dosen't seem to match the pictorial description very well.

I've seen other papers where doped SnO2 was directly cathodically deposited, in a solution that used nitric acid as an oxidizer; and in another case where O2 was bubbled into the solution; and I've read where adding H2O2 will work also.

And I have another paper where Sn and Sb were sequentially electrodeposited in layers (by conventional cathodic electrodeposition) and after a few alternating layers were deposited, the electrode was calcined @ 550 degrees C for 3 hours in air to go from Sn to SnO2. (Also, in this paper, the electrodeposited SnO2 was compared to conventional dip-and-bake Sb doped SnO2 and it was found to be much better, similar to what's described in the instant paper).

In this case, my take is that the bipolar waveform is the key. The Sn and Sb are deposited when the substrate is pulsed negative, and subsequently oxidized when the substrate is pulsed positive. (IIRC Beer used AC in some of his patent examples apparently to do the same thing).

So here's my idea: instead of Sb, we want to try bismuth (but who knows maybe electrodeposited SnO2 + Sb will work better for perchlorate than the dip-and-bake variety), so how about substitute BiCl3 for the SbCl3?

(Attached is the other paper I was referring to).

Attachment: php9wSGCj (554kB)
This file has been downloaded 1692 times

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

Edit: Here's an example from one of Beer's patents...looks like basically the same thing to me, just substitute your favorite chloride salt...

Two titanium rods were degreased and pickled and subsequently placed in a galvanic bath having the following composition:

100 cc. ethanol
100 cc. water
1 g. ruthenium chloride
10 g titanium chloride

and subsequently connected to a source of alternating current of 13 volts and a current density of 15 amp/m^2, temperature 20-30 degrees C., for a period of about 20 minutes.

After about 20 minutes both rods were coated with a mixture of titanium oxide and ruthenium oxide, the adhesion of which was still further improved by heating at 400 degrees C for 5 minutes.

The anode thus made is excellently suitable for use in various electrolyses at low current densities.

[Edited on 7-8-2011 by jpsmith123]
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dann2
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[*] posted on 7-8-2011 at 18:12



I read the paper on the TiO2 nano tubes and it sounds like the business. They state it has very high OEP in a solution of Fluoro stuff they are 'incinerating'. This does not necessarly mean it will have a high OEP in a solution of Chlorate (a Perk. cell).

I don't know what they mean when they say:
'TiO2-NTs were vertically placed into a buffer bottle under
vacuum conditions.'

What is in the 'buffer bottle'?, .........
'The electrolyte containing 0.02 M
SnCl2 3H2O, 0.02 M SbCl3, and a certain concentration of
hydrochloric acid for 5 min' , ......perhaps.
Or is the 'buffer bottle' one of two (joined using a tap) compartments. No1 (buffer bottle) contains anode + vacuum and No2 has electrolyte. The air being sucked out of No. 1 and when all air is removed the electrolyte is then let flow into the 'buffer bottle' , all remaining under vacuum untill anode is submerged. Then air pressure caused electrolyte to flow into nanotubes.
Since they say 'a certain amount of HCl acid' perhaps its not a critical amount of acid, but just enough to keep SnCl2 from turning to Oxide (ie. hydrolysing)
The is an email address at the bottom. Perhaps author will answer questions.

I tried to make a Bi doped Sn Oxide Anode by simple substituting Bi Trichloride (homemade) for the Sb Chloride and could not get it to work. Just ended up with passivated Ti. I am currently getting around to trying it again using anhydrous SnCl4 + Anhydrous BiCl3. I used SnCl4:5H20 + BiCl3:?H20 last time. (homemade BiCl3)
Substitution may or may not work. My work could perhaps be described as amateurish:P
Dann2
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jpsmith123
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[*] posted on 7-8-2011 at 21:04


Quote: Originally posted by dann2  

I read the paper on the TiO2 nano tubes and it sounds like the business. They state it has very high OEP in a solution of Fluoro stuff they are 'incinerating'. This does not necessarly mean it will have a high OEP in a solution of Chlorate (a Perk. cell).


What's important, I think, is that the electrodeposited SnO2 worked better than the dip-and-bake SnO2. (And the other paper I attached to an earlier post also said the same thing).

Quote:

I don't know what they mean when they say:
'TiO2-NTs were vertically placed into a buffer bottle under
vacuum conditions.'

What is in the 'buffer bottle'?, .........
'The electrolyte containing 0.02 M
SnCl2 3H2O, 0.02 M SbCl3, and a certain concentration of
hydrochloric acid for 5 min' , ......perhaps.
Or is the 'buffer bottle' one of two (joined using a tap) compartments. No1 (buffer bottle) contains anode + vacuum and No2 has electrolyte. The air being sucked out of No. 1 and when all air is removed the electrolyte is then let flow into the 'buffer bottle' , all remaining under vacuum untill anode is submerged. Then air pressure caused electrolyte to flow into nanotubes.
Since they say 'a certain amount of HCl acid' perhaps its not a critical amount of acid, but just enough to keep SnCl2 from turning to Oxide (ie. hydrolysing)
The is an email address at the bottom. Perhaps author will answer questions.


The paper is really poorly writen.

Quote:

I tried to make a Bi doped Sn Oxide Anode by simple substituting Bi Trichloride (homemade) for the Sb Chloride and could not get it to work. Just ended up with passivated Ti. I am currently getting around to trying it again using anhydrous SnCl4 + Anhydrous BiCl3. I used SnCl4:5H20 + BiCl3:?H20 last time. (homemade BiCl3)
Substitution may or may not work. My work could perhaps be described as amateurish:P
Dann2


Did you make or buy your BiCl3?

I'd like to try the electrodeposition method, as described in Beer's patent, using SnCl2 and BiCl3. I'm trying to find a cheap source of BiCl3 but I'm not having much luck.
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dann2
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[*] posted on 9-8-2011 at 07:40



Any experiments I have done up to now have been done using homemade Bismuth Trichloride (BiCl3:3H2O). I am not too sure how many H2O's. The non anhydrous stuff is easy to make using Bismuth metal + Aqua rega.
I have since purchased a small amount of BiCl3 which I presume is anhydrous. It just says BiCl3 on the bottle.

If you are going to go the electrodeposition route then the water should not be a problem.

Dann2

[Edited on 9-8-2011 by dann2]
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the mentalist
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[*] posted on 9-8-2011 at 08:54


Does anyone have a link to swedes blog that he mentions? I know that he posted a few links but none of them seem to work, or does he even have a blog anymore?
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dann2
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[*] posted on 9-8-2011 at 13:54



Swedes blog can be had on APC forums:
You will neen to subscribe and go to a post of Swede and a link will be close to his name.
http://www.amateurpyro.com



@jpsmith
There is another paper here using Ti02 nano Tubes with Copper in the bottom of them (for a superior Anode). It may be a bit clearer. It's in relation to PbO2 though.
http://pubs.acs.org/doi/abs/10.1021/es902336d
Dann2

[Edited on 9-8-2011 by dann2]
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watson.fawkes
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[*] posted on 9-8-2011 at 15:34


Quote: Originally posted by dann2  

Swedes blog can be had on APC forums
http://www.amateurpyro.com/forums/blog/swede/index.php
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jpsmith123
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[*] posted on 9-8-2011 at 15:41


Upon doing some more reading, I think I'm going to go with the plating method described in patent #4252618 (attached), but I'm going to try it with AC.

This method uses potassium stannate, KOH, and bismuth citrate. It seems to have become an industry standard for electroplating Sn/Bi alloy.

I'm wondering, in any of your experiments, did you happen to try SnCl2 with BiCl3? The reason I ask is because I saw a patent for an electroless plating solution where SnCl2 is the reducing agent that plates out Bi.

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dann2
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[*] posted on 9-8-2011 at 17:29



I have never tried SnCl2 with BiCl3, only ever used/tried SnCl4:5H2O

I could never get anything to work with SnCl2 (with Sb Chloride) in the simple paint and bake procedures.
Dann2
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the mentalist
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[*] posted on 10-8-2011 at 09:48


Does anyone know of a supplier that will sell mmo anodes to individuals? Cause it seems as if all suppliers require you to either be a company or buy mass amounts.
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[*] posted on 11-8-2011 at 16:32


It's frustrating when you want to do a little experimenting and then you find you cannot get the necessary chemicals at a reasonable price.

I found a company that had both potassium stannate and bismuth citrate, at a good price, and then I went to check out - only to find that they had a $100 minumum order. Rats!

Does anyony know if Bi2O3 will dissolve in a citric acid solution?
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jpsmith123
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[*] posted on 12-8-2011 at 14:34
Effect of Solvent on the Preparation and Characterization of DSA-Type Anodes


Dan, check out the attached paper.

Attachment: Effect_Of_Solvent_On_DSA_Anode_Performance.pdf (716kB)
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[*] posted on 17-8-2011 at 23:46


Bi2O3 won't work. It really looks like a good anode material, but it is not resistant to attack by acid. It will dissolve in hydrochloric acid to give a corresponding bismuth chloride.
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jpsmith123
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[*] posted on 18-8-2011 at 06:42


Bi2O3 won't work for what?
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White Yeti
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[*] posted on 19-8-2011 at 10:46


It won't work for making anodes for perchlorate cells. You mentioned a patent earlier that stated bismuth oxide could be used to make anodes for perchlorate cells.
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[*] posted on 19-8-2011 at 14:39


As far as I know, there are no patents mentioned anywhere in this thread (or anywhere else for that matter), that claim that Bi2O3, by itself, will suffice for a perchlorate anode. From what I see in the literature, it's always used with other oxides.
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[*] posted on 22-8-2011 at 10:32


I made a chlorate cell but i dont need it any more so i am thinking about to sell it, it is capable of producing 1,5 kg of KClO3 per day, monopolar,
it consumes 15kWh electricity per kg of chlorate, massive carbon
anode(i made 30kg of chlorate with it, it coroded aproximately 5% of
its mass), it is a complete plant with power supply(1kW) ready to run,
the electrolyzer is a 120litre plastic drum with removable top, sealed
with silicone, anode is a 30kg carbon block(20x30x30 cm), the cathode
is made from stainless steel, input is 5,6V 160-180A at
50°C(stationary temperature of the drum at outside temperature 20°C),
aditional cooling fan to cool the drum during hot days, aditional
chlorate isolating equipment, power supply runs on 220V but the
secondary coil has aditional turnings so its easily switched to
operate on 110V however at lover currents(120-140A) what means lower
energy loss in wiring, contacts and electrolyte lowering the specific
energy consumption

i will send photodocumentation to serious candidates
location is Slovakia, transport can be arranged




dexter
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jpsmith123
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[*] posted on 22-10-2011 at 19:42
Some bedtime reading...


I don't know how relevant this is, but it does seem to induce sleepiness.
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[*] posted on 22-10-2011 at 20:04


Wow, the title itself made me say "wahaaat?"
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dann2
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[*] posted on 7-11-2011 at 14:03




The Anode I have made (described above) seem to be holding up pretty well in perchlorate cells. There is little or no wear. They have been running now for about 40 days.
One of the Anodes is shown in picture. It was mostly used to scavange chlorate, ie. reduce the chlorate concentration of Perchlorate cells from about 20 grams per liter down to below one gram per liter. Chemical treatment of the liquor will be used to get rid of the last remaining remenents of Chlorate.

Dann2


s_anode_40.jpg - 45kB
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[*] posted on 7-11-2011 at 17:22


Not sure if this has been discussed or not but, is there a way that lead nitrate can be decomposed unto a suitable substrate just like manganese nitrate to form a conductive oxide layer.
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dann2
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[*] posted on 7-11-2011 at 18:36



No and no IMO.
Lead Monoxide will form AFSIK if you heat Lead Nitrate.
Dann2
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[*] posted on 8-11-2011 at 08:12


All right Dann is that the Bi/Sn oxide anode or is it LD? If it is the Bi/Sn please tell us more. It would be very nice to see that it's working.
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