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Author: Subject: Perchlorate manufacture (not) with Graphite
12AX7
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[*] posted on 1-1-2008 at 20:53


After a two-day run, today I emptied the cell.

The electrode has become bubbly: clearly, the platinum did NOT make a very good bond. Some areas are still connected, but the whole surface is not covered.

I also prepared an anode at higher current density, finding deposition rate does not depend much on current density. The deposit is still black. It also performed very poorly in mechanical terms, without even exposing it to anodic conditions. Attempts were made to passivate or anodize the exposed areas, with no useful effect.

I tested it in a bromate cell: the areas of exposed titanium corroded rapidly, filling the cell with white hydrous muck. Titanium is listed as incompatible with bromine, so this shouldn't come as much of a suprise. I recommend using graphite, solid platinum or a suitable oxide anode in a bromate cell.

In contrast, the perchlorate cell's titanium substrate is in original condition, minus some flakes of platinum.

I have found that boiling sulfuric acid is somewhat capable of attacking titanium, producing a blue or purple corrosion product which washes off. Boiling-hot 50% NaOH causes a slow darkening of the surface, which can be removed with 3M HCl. Fluoride is capable of etching the surface, and elemental or anodic bromine is capable of heavy pitting. HCl(aq), Cl2 and anodic perchlorate conditions are all inert.

Presumably, I need a combination of one of these corrosive processes to expose titanium, with a levelling agent in the bath to produce bright platinum. I don't know why I'm not getting the bright deposit I did originally.

Edit: Oh, and the cell liquor. I weighed 103.5 g solution and added concentrated KCl solution to it, immediately producing a thick, chalky white precipitate. I will seperate it from KClO3 and determine the concentration gravimetrically, calculate yield, then add a nearly stoichiometric amount of boiling, concentrated KClO3 solution to precipitate KClO4, leaving NaClO3 in solution.

Tim

[Edited on 1-1-2008 by 12AX7]




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chloric1
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[*] posted on 2-1-2008 at 03:54


Quote:
Originally posted by 12AX7
I recommend using graphite, solid platinum or a suitable oxide anode in a bromate cell.

Tim

[Edited on 1-1-2008 by 12AX7]


That reminds me, remember reading in US339996 that they recommend not using cobalt bromide as an electrolyte to deposit cobalt oxide anodically. It was something to do with the voltage to break down the bromide being less than 0.7 Volts not allowing the oxide to form. Merk lists Co3O4 as dissolving in HCl with evolution of chlorine. The bromide ion may reduce it to a point that it will dissolve or no longer function.

Since this oxide will be the backbone of our anode design, I am not sure if it can be used for bromate synthesis. Any thoughts on this?




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[*] posted on 3-1-2008 at 05:24


Sorry to hear the Pt didn't stick. I know the feeling. I wonder if electrocleaning or hydriding of the titanium would've helped?

I was able to plate a thick, nice-looking layer of cobalt onto hydrided Ti, very successfully (it had to be sanded off), but I couldn't do anything with cobalt oxide.

I still think anodically co-deposited Co3O4 and MnO2, followed by baking, is worth a shot, but I don't have a furnace yet, so I unfortunately won't be able to try it in the near future.
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[*] posted on 3-1-2008 at 06:33


I remember reading that platinum cannot be electroplated to titanium from aqueous solutions at all.
What I can say for sure is that platinum clad titanium electrodes are made by a molten Pt salt electrolysis at a temperature above 500°C where the oxide layer on titanium is not stable.




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[*] posted on 3-1-2008 at 06:52


I was able to plate cobalt onto Ti by hydriding it first...and patent #4127709 claims to accomplishe nickel plating on Ti, also by hydriding first.
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[*] posted on 3-1-2008 at 13:44


This is what you're referencing:
http://www.finishing.com/4400-4599/4497.shtml
That is ridiculously expensive, but it is a method.

I should like to correct garage chemist on that, it is indeed possible to plate Titanium in aqueous medium with platinum.
It is anode pretreatment that is absolutely essential!!

I sent Tim hydrazine sulfate too, because I remember reading a patent about electroless, jewelery-finish (therefore adherent) platinum plating done hydrazine sulfate. Personally, I don't think he did sufficient etching and from what I've seen and experienced, Ti needs aggressive pretreatment. So in addition to sanding, other chemical etches must be performed, and the anode-to-be kept under water all the time, only being exposed to air as it is transferred to the plating vessel.


Additional references provided to me by a friend on another forum, who is a professional metal plater who also says it's quite possible.

http://www.finishing.com/243/65.shtml

http://www.finishing.com/134/56.shtml

http://www.hikifune.com/english/product/toku/ti.html
( a company that uses a proprietary method to platinize)



Example regimen for pretreatment courtesy of Dr. Trevor Crichton:

"Titanium can also be electrochemically processed by etching in a solution of:
NH4HF 10-40g/l
H2SO4 5%v/v
Temp 20C
Leave for 30 secs or more AFTER gassing starts.

The titanium is then activated in:
HF(40%) 50-70ml/l
HNO3 50-100ml/l
H2O2 100-200ml/l
Temp: RT
Time 5-10 secs

Once activated, the titanium can be strike plated with Woods Nickel. It is essential that NO RINSING takes place between the activation and strike plating. I believe this was documented in Trans. IMF. 1966 p74 "

That is very much in line (as far as pretreatment goes) with what I remember reading. Hence the reasons I sent what I sent to Tim.

[Edited on 3-1-2008 by Fleaker]




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[*] posted on 4-1-2008 at 05:59


Well I sanded my piece of Ti with 220 grit SiC paper, washed it with detergent solution, cathodized it for 10 minutes at about 50 mA/cm^2 in 10% oxalic acid, and plated it with Co...and I challenge anybody to remove the Co.
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[*] posted on 20-1-2008 at 10:05


Hello,
The following was posted by DerAlte in another thread. I though I should cut and paste here for completeness.

Dann2


Quote:
Originally posted by DerAlte
To the best of my knowledge, perchlorates CANNOT be produced by the electrolysis of chlorates using carbon as an anode.

I had two samples, produced in 1995. One, labeled Chlorate (call it ‘C’ for short) was produced by electrolysis of saturated NaCl using a carbon anode. Part - the major part – was used by metathesis with KCl to produce KClO3.

The rest was then somewhat purified to get rid of as much NaCl as possible and subjected to further electrolysis, following a convincing sounding procedure “guaranteed” to produce perchlorate (found somewhere on the WWW). I added KCl to the electrolyte at this point order to precipitate any KClO4 so formed. I kept temperature much lower (by reducing current density and ohmic losses) than in the first case, since I assumed the process was a purely electrochemical ion oxidation conversion, with a different cell configuration (wide anode/cathode separation). A precipitate was formed.

This was bottled as ‘KClO4 (impure)’ – call it sample ‘P’. The only use I ever made of this was to demonstrate a few pyrotechnical reactions to my younger son. It seemed less reactive than the sample C.

When Dann called into question its composition, I sought methods available to me to determine this. I did not have conc. H2SO4 available nor Methylene Blue.

Chlorates react with any strong acid to give either Cl2 or ClO2 or a mixture; perchlorates do not, due to the kinetic barrier which accounts for their relatively poor oxidation performance, although the thermodynamics favor it over chlorates.

(1) A test of P with HCl gave off a gas that was either Cl2 or a mix with ClO2, by nose test. Conclusion: P contains Chlorate. This does not definitively say it does not contain perchlorate, however.

(2) Saturated solutions were made of both samples and a drop placed on a microscope slide and allowed to evaporate slowly. Crystallization was observed under X50 mag.

Result: C gave lozenge shaped crystals characteristic of KClO3, plus a few needles. Both of these forms are possible under the monoclinic classification of KClO3, where sides may be unequal but parallel and only one angle is a right angle.

P also gave the same shapes in the main – only one crystal was orthorhombic, where all angles are right angles, but sides unequal (unlike cubic) which is characteristic of KClO4. However, needles were also produced, and perchlorate can also be of the needle form (it is isomorphic with KMnO4, which tends to make needles in my experience).

Conclusion: If there was any perchlorate in P, it was a small amount.

(3) 1.000 g (+- 0.005g) of each of C and P were dissolved in 33.3 mL (+-0.3mL) water at RT – both dissolved. This shows that less than 70% was perchlorate. The solution was so chosen that pure chlorate would be just saturated at 0c. Both solutions were cooled for 3 hrs. in a water bath in a refrigerator to slow the ice melting. One or two small crystals were then seen floating in C; none in P. The P solution was somewhat turbid at the start and a fine white ppt. settled during cooling, but there was very little of it. Examination under magnification showed what looked like particles of a fibre. Non –crystalline.

The conclusion from test 3, (solubility) indicates that not more than 0.25g in solution (<25%) could possibly be perchlorate. Taking account of the common ion effect, even including activity coefficient (from CRC) reduces this to a maximum of 0.063 g (<6.3%).

Overall conclusion: if perchlorate was formed at all, it was probably less than 5%. I was merely oxidizing carbon! Moral: Don’t believe what you see on the web, however convincing. And do some tests, always…

DerAlte

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[*] posted on 26-1-2008 at 21:20
My Cells (plural)


Seems proper to put in here, as all three are running perchlorate at the moment.

Put together two new cells last night and tonight. They both consist of 4" steel pipe, well rusted on the inside (and sulfury -- pew!). A 1/8" steel plate was hacksawed to shape (I need a bandsaw...) and welded on. The first one had a pinhole leak after the first pass, while the second was perfectly sealed as welded.

The first one seems to be hogging current; the large cell has cooled down substantially, and is probably running much less current now. The ballast is reading near 1V of drop (corresponding to about 30A total consumption), probably a good point to cut it in half and see if I get more current flowing through them all.

I'll probably set one to perchlorate duty, and the remaining two for chlorate production. That should about balance out.

We'll see where I get by june! ;)

Tim

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[*] posted on 27-1-2008 at 05:17


Your cells are running your Pt plated Ti Anode, Tim?
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[*] posted on 27-1-2008 at 11:33


Yes, all three of them. At least, what area of the anode *is* plated...

Tim




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[*] posted on 27-1-2008 at 23:37
Intended Use Form


I'm still working with PbO2 anodes. Never can seem to make one that doesn't want to
disintegrate in the cell.

A general chemical supplier that I've done business with now wants the intended use form
for KClO3, KClO4, NH4ClO4, and NH4NO3. Now more reason for me to make my own chemicals.
It appears that the CPSC's bullshit is scaring more and more suppliers.




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[*] posted on 20-6-2008 at 20:40


There is PbO2 sheet in the car battery May we use of it(for anode)?



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[*] posted on 20-6-2008 at 21:11


Read the archives, that PbO2 is not nearly robust enough.

Tim




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[*] posted on 15-7-2008 at 22:00


I'm not sure if this has been covered, but there are sources of MMO coated Ti anodes out there. There were a few (overpriced) ones on eBay, a supplier in India, and a pyrotechnical company in the States. For everyone looking to go this route (and I would highly recommend it), PM me for details.

These electrodes are stellar choices any way you swing it. They will apparently show no sign of wear after even tens of years if treated well. I can assure you mine have served me well since I purchased them.

As far as what the MMO coating is, I actually have no idea. I didn't inquire, but they sure as hell work wonders on chlorate/perchlorate cells.
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[*] posted on 15-7-2008 at 23:47


Quote:
Originally posted by Lewis
I'm not sure if this has been covered, but there are sources of MMO coated Ti anodes out there.


Hmmm...! Yes it has been covered. See the various anode and chlorate/perchlorate threads in Technochemistry. As far as I'm concerned, the ready availability of exotic anodes has just about sounded the death knell for home anode making, other than perhaps PbO2 coated Ti.
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[*] posted on 15-7-2008 at 23:56


Here's an interesting coating scheme:P

http://www.youtube.com/watch?v=cBpcF8ipqq0&feature=relat...
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[*] posted on 16-7-2008 at 14:14


Quote:
Originally posted by Rosco Bodine
Here's an interesting coating scheme:P

http://www.youtube.com/watch?v=cBpcF8ipqq0&feature=relat...


Damn it Rosco I got a chubby. Can't concentrate on chemistry....be back later:P:P




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[*] posted on 20-7-2008 at 06:15
Perchlorate from MMO?


Quote:
Originally posted by Lewis
.....................

As far as what the MMO coating is, I actually have no idea. I didn't inquire, but they sure as hell work wonders on chlorate/perchlorate cells.


Hello Lewis,

Have you actually made Perchlorate with the MMO?
Have you started with Sodium Chlorate (pure or close to pure) or with Sodium Chloride.
How do you purify the Perchlorate (if you do).
All and every detail appreciated.

Cheers,
Dann2
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[*] posted on 19-8-2008 at 10:10


Quote:
Originally posted by chloric1
Quote:
Originally posted by Rosco Bodine
Here's an interesting coating scheme:P

http://www.youtube.com/watch?v=cBpcF8ipqq0&feature=relat...


Damn it Rosco I got a chubby. Can't concentrate on chemistry....be back later:P:P


:D;) Yeah, that is an example of spray pyrolysis gold coating if I ever saw one.....or maybe she just melted and fused all her jewelry there in a transient moment of sultriness:P There's no hitting that lady with a snowball, as it would simply flash to steam in midflight a foot away from impact:P
kind of like the comet over Tonguska;)

Here's a clip of an earlier appearance.
http://www.youtube.com/watch?v=TxXPDvs4pDY

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