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Author: Subject: Thoughts On Anodes
woelen
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[*] posted on 11-2-2015 at 08:14


Your anode is a bad anode, probably not meant to be used in concentrated solutions. Swimming pool anodes are used in very very dilute solutions. They probably wear out in such solutions as well, but because of the very low rate, they last for a long time when used as swimming pool chlorinator. In your situation, you are using the anode in a much more concentrated solution and they wear out at a 100 or so times as high rate as in a swimming pool.

My MMO anodes have been used for many days in concentrated brine at 5 V and I did not even see a tiny little speck of degradation and the liquid remained clear as water, no flocculent stuff nor junk floating on the surface. With bromide I had degradation, but not of the MMO, but of the titanium substrate.




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papaya
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[*] posted on 11-2-2015 at 08:21


Thanks woelen, never thought there are different kind of MMOs, especially when it was stated as "Ruthenium/iridium oxide coating", very interesting.
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[*] posted on 11-2-2015 at 08:45


So how do one pick a suitable one?
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papaya
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[*] posted on 12-2-2015 at 08:58


Some interesting news regarding my "bad" anode I thought I have to share with you. As I already said the problem was the anode seemingly being destructed during NaCL electrolysis even at low current densities - after some time I evidenced brown junk floating on top of liquid and other white stuff in the volume, several attempts -all with the same outcome.

But before discarding the anode as a "junk" one I decided to test if changing NaCl "brand" may help since we cannot be completely sure on table salt's real composition! Guess what ? I bought salt from other supplier - the cheapest brand of almost technical quality, even containing some earth as it occurred (it's just halite mineral ground down without purification). This time NO brown junk during electrolysis - almost clear solution, and only after 12 hours I discovered some little amount of white stuff floating in the volume. I'm still thinking what this could be - maybe some calcium or magnesium salts turning into insoluble hydroxides?
Can anyone tell me how to purify NaCL for further tests ? Recrystallization may not work since temperature dependance of NaCl solubility is weak, is there any other option?
Hell, table salt I used previously might contain some additives at ppm levels (perhaps iodine and ferrocyanide), how this could affect results so much?
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[*] posted on 12-2-2015 at 09:02


Platinum anodes will tarnish and degrade in extremely alkaline solutions. Better use an MMO anode.
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papaya
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[*] posted on 12-2-2015 at 09:05


That is about MMO!
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[*] posted on 12-2-2015 at 09:32


To purify NaCl just recrystallize it, filtering off insolubles while the NaCl is in solution. You could also try washing it with solvents I guess..
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papaya
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[*] posted on 12-2-2015 at 09:40


How do I recrystallize if solubility doesn't change with temperature? Really folks, how to purify NaCl?
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[*] posted on 12-2-2015 at 09:48


"Table salt" is probably not the best choice. First, while safe, it is not pure BY DESIGN, it has iodide, and more importantly (in terms of mass of offending product) anti-caking agents.

Your best bet is water softener salt, and if your ultimate goal is potassium chlorate or perchlorate, just bite the bullet and start with the potassium chloride.

I'll be the first to acknowledge how nifty it is to keep the NaCl concentration up, knowing the liquor is slowly being saturated by the much more soluable chlorate, but once you've done the "double-decomp" and see the KClO3 falling out of solution, it's pretty much all you need to see, especially when you consider you had to buy the KCl anyway.

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papaya
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[*] posted on 12-2-2015 at 10:04


Varmint, I don't want to perform chlorate synthesis, I'm just testing "suspicious" MMO anode I was given. Suspicious due to the problems I described, one of which(brown junk) is solved now. Now I suspect "hard" cations in water/salt, thus I ask for a method of purification.
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Fulmen
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[*] posted on 12-2-2015 at 10:13


Good question. A wash would remove any readily soluble compounds from the surface, that could be enough to get rid of caking agents. As for recrystallizing I suspect the only practical route would be to dissolve it and boil it down again. Or can one utilize a mixed solvent system?
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[*] posted on 12-2-2015 at 10:54


The reason for my comment was, I have MMO from the same supplier, and there are no such unexpected results in my cells.

My cathodes are Titanium grade 2 (chemically pure), the anodes are attached to similarly pure titanium rods through a special process I developed myself.

I've run moderate current density, and I've cranked the current up to expected point of failure and never saw anything but what I would call "perfect operation".

If you have MMO, you either plan to make chlorates, or, if you use a salt bridge or expensive commercial membrane, hydroxides and hypochlorites.

If you bought it "to test it", it is your test that needs work, not the quite excellent anodes.
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papaya
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[*] posted on 12-2-2015 at 11:05


I don't remember where I mentioned seller's name, whom you defend so much Varmint? And please don't start giving me "advices" what I should do with anode and what I shouldn't, since the test I described is far from being damaging to this type of anodes and the results are "no more than catastrophe" so far. Of course I could openly blame the seller for the shit he sells sometimes (maybe depending who is the buyer and from where, ah?) as well as not answering the messages I sent him, but I don't do that unless I can be 100% sure. So why are you 100% sure anodes are "quite excellent" ?
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[*] posted on 12-2-2015 at 14:21


I'm not defending Laser so much as pointing out what a moron you are for using tap water and table salt to "test" MMO anodes you bought to make chlorates.

Clear enough?

And I'm quite sure the anodes are excellent because used in a scientifically competent manner, they work as designed without the slightest deviation from expectation.
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papaya
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[*] posted on 12-2-2015 at 14:36


Now explain me in a scientifically competent manner how did you purify NaCl to get super results, since I don't remember anybody writing here they used analytical grade and deionized water to avoid some strange flocculent precipitate (which I'm afraid is TiO2). That was my original question, which you are now trying to turn into flame! moron? that's how you are treated by everybody maybe, unless you get more respectful to other people.
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[*] posted on 12-2-2015 at 15:05


I'll remind you to look at my original post, to which you replied "an anode I was given", yet earlier you indicated you obtained it from "the well known seller" (who's name happens to appear on multiple pages here).

So, you bought it, didn't have a clue how to perform even a basic test, and are now claiming to be researching this probably sub-standard anode. Hint: Do not change your story mid-stream as a means of preserving your integrity.

Then you amped up your response to include me not giving you advices, his anodes being shit, meanwhile there are lots of buyers here that are quietly churning out all manner of chlorates, hydroxides, and hypochlorites because, once again, the anodes work well when put to use by those qualified to understand how they work and how best to put them in service.

You try to pass yourself off as a qualified chemist, yet you used tap water and table salt? Have you never seen how much gunk is in potable water that has no place in a scientific procedure? Especially one where you pretend to be characterizing performance? You claim your original question was how to purify? Look back to your first post in this thread, then apologize for trying to lie to me.

You shouldn't have posted in a thoughts about anodes thread, you should have opened one of your own, in beginings, stating "I bought an anode, now what?"

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papaya
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[*] posted on 12-2-2015 at 21:59


What? You imply I'm hiding something because I said "given" instead of "bought" this time? If I had to hide something would I ever post here about issue? listen, I'm getting tired of this pointless dialogue with you honestly and don't see what are you try to prove. I told the story as it happened (and as it progressed later) and finally asked for a method of purification of NaCl, since only then I can make any conclusion! Yes I used tap water as many others did with NO problems, isn't it? What is the meaning of using distilled water if you have to use technical/table salt?
Or was it supposed that I will act like many clueless people, who bought anodes and just hurrily put it into 100amp chlorate cells directly with KCl,so nobody sees strange precipitate mixed with tons of chlorate? I invested into anode mostly because it's a valuable and not so easy to get thing where I live and for broad purposes ,future experimentation, for chlorates I made my own cobalt oxide anodes one time btw and got tired of "chlorates"(as you continually retiterate) already back in the past. Why is it "suspicious" when one tries to look more thoroughly into a thing for which he paid, especially if there're reason to be worried?
Anyway, I don't like this kind of dialogue, If anybody wants to add on the subject only then I'll answer, this is lost of a time.
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[*] posted on 12-2-2015 at 23:29


hey there guys,... I'll just cut in here for a sec, I bought laser's MMO as well. in addition to the couple I spot welded( shown bottom page 44 this thread) I made a larger single plate cathode from Ebay sheet stock, gr2 Ti, in order to have a larger surface area. dremel action to liberate it from a larger sheet. looked great, all shiny, polished and blunted edges,. for about 2 nights... ya I know, so what a cathode, boring, well..

I had been making bleaching solution for cleaning up, not chlorate,.. I have a pool that I hate getting green. it was measured by occasionally stirring and placing one drop on a cut paper towel tube. brown, free and convenient; showed the bleaching action very well. any how I was using both morton iodized and solar salt( softner), in a small jam jar as an initial test of the spot welds I had made in open air with out any flux. they were fine and lasted 5+ days, on while I was home, with out so much as a blemish. the solutions were clear but became strong yellow, with out ever turning cloudy. when I scaled up with the new shiny hand made one. we had an empty gallon wine jug and I wanted to make bleach/bleaching solution in it. after working everything out in one evening, I was in a rush to get sleep before too late... and wired them electrodes backwards! plugged it it, set it to 5V 1.5A awoke in the morning to a wonderful mess. the gallon wine jug was half full of a white voluminous chunky stuff that shifted to a more brick red and much thicker foam at the top of the jug. I was horrified and immediately figured what I had done. called my self a dork and went to work bummed.

later on inspection the MMO was covered in red/orange/white foamy crap and the (intended)cathode plate had been cut down by more than a third. albeit, the erosion looked interesting( bright side of things right?) the surface was still shiny were it wasn't eaten, all the revealed metal was black colored. I had assumed both were trash. but after a cleaning and changing purpose,the MMO is a nice dark black with shiny cut edges. no damage. I had been using it as counter electrode to plate copper out of E-waste I have, onto copper tube and sheet. I swear the thing is bullet proof, for a lill MMO strip I spot welded my self.

I have had the thing running with e-waste( HCl + cellphone and computer boards), sulfamic acidified e-waste, sulfamic + cupronickel, strong presence of HCl, sea salt, Iodized table salt, and countless hitch hikers from the trace resists/enamels/solders/inks/wide array of metal salts in sol. not all at one time, but many of the parameters overlapped in at least a few experiments. its still running like a champ.

the small scale tests with the e-waste, was attempting systematic depletion of specific metals in sol. none has ever been dumped and I am getting tired of saving batches to deal with. boil down( out side and slowly, neutralize, drop in aluminum scrap and store the cake. things looked good, copper was plating out easily and made some impressive yet feathery( brittle) crystals. A touch of citric acid and sulfamic seems to smooth the process a bit. I only noticed a darkening of the crystals once, but it was oxidation as far as I could tell, nothing else was plating with it at least. when I changed from the portable electrolysis device I had made, to an ebay bench top power supply, I accidentally switched the polarity and partially copper plated the MMO, then switched back and stripped it off. no harm yet again.

some of this could easily be considered just dicking around, and it was other than the first hand learning and subsequent reading, notes and what not. regardless, the MMO is far more resilient than I would have thought.
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[*] posted on 13-2-2015 at 02:52


papaya:

Thanks for finally coming clean and getting your story straight or straighter, I'm sure you had to go back and read what you wrote to get it "right" this time. Too bad you weren't man enough to apologize though.

See, I can amp up the "ass" with the best of them, and if you had shown even a hint of respect along the way, you would have found I can amp up the "good guy" with the best of them too.

My advice for you is to back up a bit, think before you post, and try, as hard as it might seem at first, try not pass yourself off as a research chemist, especially when peoples posts based on the evolving truth directed you to ask such an elementary question as how to purify a salt.

Have a great day bud.
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[*] posted on 27-1-2016 at 08:39


I am new to chlorate synthesis using mmo and i have read that tap water is bad for your anodes but the place where i live in has tap water from desalination plants with almost no fluoride content and so far i do not see any erosion and the solution remains clear after 2 weeks and 2 runs also the anode is still rough and not deep black and smooth.

But i heard that iron and barium is really bad for them only time will tell if i had made a huge mistake.

I couldn't find any bottled water brands that are any safer and spending on an RO DI system just for this.
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[*] posted on 27-1-2016 at 18:18


Quote: Originally posted by mysteriusbhoice  
so far i do not see any erosion and the solution remains clear after 2 weeks and 2 runs also the anode is still rough and not deep black and smooth.

How much power are you using?




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[*] posted on 29-9-2016 at 12:19



Has anyone ever suggested using Pt leaf wrapped onto a titanium rod for an anode.

Pt leaf is available here

http://www.goldleafsupplies.co.uk/acatalog/Platinum_Loose_Le...

Platinum is 21.45g/cm^3
1000 sheets of 8 by 8 cm weighs 32 grams. I make the thickness of the sheets 2.33 micron. Too thin I would imagine.
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[*] posted on 29-11-2016 at 13:14


https://books.google.com/books?id=x-oOAAAAYAAJ&pg=PA71&lpg=P...

Chromium phosphide was "not seriously attacked" by chlorine gas evolved upon it when used as a material for an anode. Not sure about the specific conditions in a chlorine cell (pH?) as opposed to the one from which this observation was made -- which might be unreliable as it was made in 1892. "When, in 1892, columbus sailed the skies blue" as they say.


[Edited on 29-11-2016 by halogen]




F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat with the evolution of chlorine.
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