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12AX7
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Oh, same old graphite bar seen above.
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dann2
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Hello,
That is a high temperature for Graphite.
Would it be possible to weigh anode every half day to get an idea of wear.
Some nosey git would like to know
Dann2
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12AX7
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I doubt weighing it directly would be an effective plan, given the possible difference in absorbed and surface moisture, salt and, if time is taken to
try to clean it out, soaking time, rinsing, drying, etc.
I would estimate I was getting about 10 grams of graphite muck every week, at 20A. Tomorrow I will process this electrolyte to see what's happened.
(That counts to four days, but current was running intermittently due to faulty connections.)
Tim
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12AX7
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Curious! Today when going to change the liquor, I noticed the PVC pipe spacers were floating!
I don't know if this is due to a chemical change (hydrogen bubbles reducing or chlorine and oxides oxidizing?), liquid density, or mere hydrogen
bubbles adhering to them. A stir, knocking them around, failed to permanently submerge them, so my liquor must be unusually strong or something. It
should be just as saturated with NaCl and NaClO3 as usual...I haven't changed my process except in temperature (which should reduce density!) and
current flow.
Tim
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12AX7
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3.5 kilos, minus what water is still present (no more than 0.5 kg I would guess).
This is the result of a week's run (about half of those days running, due to a shortage of brine), which produced 3 kg of NaClO3. This was dissolved
in 1.6 kg boiling H2O and mixed with 2.1 kg KCl dissolved in 4.2 kg boiling water to precipitate the KClO3. Another 0.5 kg or so should be dissolved
in the leftover liquid, giving yield around 85%.
And no, I don't really have a use for all this chlorate... Right now my interest is to tweak my process in terms of efficiency, time spent, etc.
Tim
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Eclectic
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You can use some of it to try making a flux for brazing cast iron.
1 part borax
1 part boric acid
1 part sodium or potassium chlorate
The idea is to have it be oxidizing at low temp to burn off oils and carbon in the cast iron and be neutral at brazing temps.
Something like this used to be available as a two part mix, but it's no longer made.
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hashashan
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12AX7
holy cow ...... one week? what was the current through the cell?
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12AX7
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Around 60A.
Tim
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chloric1
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Tim
I thought your PC power supply burned up. Did you get a new one? Hey one thing you can do it get some oxalic acid (Meijers has 2 pound jars near
drain openers) and mix with your potassium chlorate to get a uniform crystal mix and then add enough battery acid to submerge. These 3 ingredients do
not react intitially at room temperature at least not at perseptable measure anyways. Immerse a test tube of the mix in water above 60 Celcius and
you get on-demand chlorine dioxide. Great for water treatment while camping etc.
Don't store ingredients mixed. Make ony what you need. It smells like chlorine AND nitric acid  SEXY STUFF
[Edited on 7/24/2007 by chloric1]
[Edited on 7/24/2007 by chloric1]
Fellow molecular manipulator
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hashashan
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60A ..... very nice that you could controll such currents .... when i push more then 10 amps i have a real trouble to keep the cell cool.
Do you use some stirrer or anything else? what is your power supply? what were the electrodes, the distance between them ... can you specify all the
small details? I am very interested in such high yields.
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Rhodium
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I was directed to disscuss my electrode questions at this thread (I hope it's the reigth one^^)
(here is the old thread http://www.sciencemadness.org/talk/viewthread.php?tid=8879 )
@garage chemist: It is hard to believe that coated anodes corrode, because they are used in industrie.
I don't want to use graphite (because of his negative attributes) and chromate (because of its high toxitiy) for my cell.
(di-)chromate will create a layer of hydratet oxides of chromium around the cathode. (So the catalitic effect will not take place in solution or
directly by the chromate). And metallic chromium is always coated by an passive chromium oxide layer, right?
(In fact I've seen twice sites which told that under some circumstates chromium will get as chromate in solution.
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gnitseretni
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would a 1/8" dia tungsten rod make a good anode material?
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Xenoid
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| Quote: | Originally posted by gnitseretni
would a 1/8" dia tungsten rod make a good anode material? |
No! Check out Dann2's website for a discussion of suitable anodes;
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
If you are making your first chlorate cell, graphite or carbon "gouging rods" (remove the copper) are the best choice!
Regards, Xenoid
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gnitseretni
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Ok, thanks. Carbon it is
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chloric1
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Well I completed my first 14 day chlorate run about a week ago. My observation conclude that graphite is the best choice. Take note the quality of
the carbon you choose is important. I started with a mediocre grade graphite rod and it was destroyed in 6 or 7 days. I now have two shorter pieces
of this rod. I switched to a "denser" stronger graphite and the anode only suffered minor pitting. So may recommend EDM grade graphite. It is
reasonalbly priced on ebay but expensive everywhere else.
I don't have indigo testing solution so I tested for chlorate by trying to ignite the dried filter paper I used to clarify my electrolyte. WOOSH!
Burned so hot that some NaCl vaporized and condensed salt on a near by rod of metal!
I wanted to crystallize sodium chlorate but I ony have 300 grams per Liter more or less. So I will boil down and add more saltwater and rerun for
another week to 10 days. This stuff is soluble!!
[Edited on 8/27/2007 by chloric1]
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Xenoid
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@ Chloric
Congratulations!
Sounds just like my experiences, although I moved to gouging rods (they were so cheap) and I just run them to destruction.
If your cell is not too big, say less than about 2.5 litres, magnetic stirring improves efficiency, it also allows you to add say 5g, 10g or even 15g
per 100mls extra solid NaCl to the saturated solution you are already using. If you note the time when all the solid NaCl dissolves during the
operation of your cell, you can work out the exact "true" efficiency of your cell, eg. 40,50,60%. Obviously, it also results in higher final
concentrations of NaClO3.
When concentrating your solution, note the type of crystalisation occurring at the saturation point;
Flashes of large, sheet-like rafts on the surface indicate NaClO3 saturation, so remove and cool etc.
Tiny, crystals forming on the surface and clumping together indicate NaCl saturation, at about the same time you should see a fine white "sludgey"
deposit of NaCl forming on the bottom of your evaporating container. Continue to concentrate a little further and then hot filter this NaCl out of the
solution. You can then cool, and "harvest" a crop of NaClO3 from the remaining solution. You can repeat this several times, although the law of
diminishing returns sets in and starts to make it not worthwhile. I would normally do two or three cycles.
Regards, Xenoid
[Edited on 27-8-2007 by Xenoid]
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DerAlte
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Xenoid said
| Quote: | If you are making your first chlorate cell, graphite or carbon "gouging rods" (remove the copper) are the best choice!
......
I moved to gouging rods (they were so cheap) and I just run them to destruction. |
Agree 100%! No amateaur should bother about a few cheap rods or power efficiency. I haven't done a chlorate or perchlorate manufacture for a few
years, but my best results were gotten using the inverted trough arrangement, where the mixing with the chlorine produced seems best.
It's difficult to be truly scientific with this electrolytic Oxidation. There's a lot of lore in it - the pyrotechnics boys are stiff with ideas. To
hell with carbon erosion! I run the cells at high current density and about 60C (self heating). And I maintain you can get perchlorate with carbon
anodes - I have done it. All the perchlorate I have comes from the last attempt.
I always used NaCl as the starting material. It seems to convert easier than the KCl, although I also add about 10% KCl. Why I'm not sure. If you add
KCl and attempt the perchlorate step ( by upping the voltage and current density when most of the chlorate has formed) KClO4 will precipitate to the
bottom of the cell, along with carbon rod detritus.. Likewise KClO3 if the solution is concentrated. The pH needs to be near neutral (6-8) - I
believe this is the most critical factor.
The high temp encourages the disproportionation of the hypochlorite (and the erosion of rods). Many say dichromate is necessary for efficiency. It
does work without. I add a little KMnO4 (enough to color red) -- more an act of faith than science!
To crystallize the sodium salt(s) is difficult. I always convert them to the far less soluble potassium salts. Purifing sufficiently to give a
product suitable for some pyrotechnic needs (getting rid of the sodium yellow) is quite difficult, but in the perchlorate case not so difficult - one
or two re-crystallizations with careful washing with ice water does it. Even with chlorate, there is a large difference of solubility between the Na
and K salts.
Finally, I think the prize has to go to 12AX7 for his innovative and massive cell, huge power supply and prodigous yield. Positively industrial! The
dirty mess he shows in the beaker is absolutely typical of what you get with graphite anodes. Not for those who don't like getting their hands dirty,
and not for Kitchen labs! Well suited to a ventilated garage or outhouse (well, shed).
Regards,
Der Alte
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12AX7
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Which reminds me, I have another five pounds on KClO3 the shelf (I've sold a total of 6 pounds so far), plus my personal stock, plus some 6 pounds of
NaClO3. I've got the bottom half of a milk jug worth of KClO3 to hot filter and recrystallize.
My anode has also shrunk dramatically over the last few months. It's nicely rounded and about half its original dimension (1.5" square down to about
3/4", rounded). Oddly, I'm still running about the same current (typical current is 30A with room temperature liquor, up to 45A when hot), which
means current density is roughly quadrupled. At least the copper plated connection isn't corroding further -- there was a vein of excessive porosity
in this bar which piped chlorine-rich goo straight up to the connection, but now, solution can't even reach it because the rest of the vein has worn
away.
I should let the cell run for an extra couple of days some time and see if perchlorate is formed. Hmm, if I'm going to do that, I'll want to get the
potassium out of the liquor and prepare the next anode...
Tim
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DerAlte
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@12AX7
My god, man! You have gone commercial! (watch out for Big Brother if he lurks around your area.)
Don’t forget to tell us if you get any perchlorate. I don’t think anyone believes me when I say this can be done with carbon anodes.
Possible reactions for ClO4- production are
(1)Anodic oxidation: ClO3- + H2O -- > ClO4- + 2H+ +2e- ( -1.2V SEP at standard conditions)
(2)Disproportionation: 4ClO3- -- > 3ClO4- + Cl- (You can show this one by boiling a strong solution of KClO3 for a fair time. It is a slow
process. Ultimately some less soluble perchlorate will precipitate)
(3)Oxidation in solution at large by ClO- ions; ClO3- + ClO- -- > ClO4- + Cl-
Who knows if and which happens? One thing is sure – it’s not a healthy environment for the poor carbon anode!
Regards,
Der Alte
[Edited on 27-8-2007 by DerAlte]
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chloric1
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Progess
Well, I was not able to identify any chlorate looking crystals from my first run even though the filter papers burned like slow gun powder. I might
have only had 300 grams or 350 grams NaClO3 per liter so I reran at 5.97 AMPS for just under 168 hours and the last 48 hours where without the lid.
As Tim says the salt spray is atrociuos but I concentrated the solution down from 2 liters to 1 liter! I think I flipped over the balance and I have NaCLO3 as major constituant and NaCl as a minor one. I have maybe 100
or 150 grams of clear cubic crystals that fell out during filtering. They look like bust glass they are so clear. Unfortunately, they taste much
like NaCl. The chlorate is a cooling saline taste simular to the nitrate. I know I am looking for tablet type crystals and I am boiling down to try
to affect this. Maybe most of my chloride is out so this should'nt be too hard. I will return the cubes to solution and blend with more saturated
NaCl for the next run. I might not crystalize all of the chlorate and put some of the mother liquor back in the cell to give the electrolyte a head
start. I will let you know maybe with photos as things progess.
@ Deralt- You know maybe Perchlorate may form at graphite anodes but would anybody want to try? The yields would be poor and after destroying the
significant chlorate amount I feel most would be disappointed. Don't worry I have a couple ideas for composite anodes. That is if I ever have free
time to make them.
[Edited on 9/8/2007 by chloric1]
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DerAlte
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@ chloric1
| Quote: | | Deralt- You know maybe Perchlorate may form at graphite anodes but would anybody want to try? The yields would be poor and after destroying the
significant chlorate amount I feel most would be disappointed. |
Yes, an old fool like Der Alte would! It's the only way I've ever made perchlorate. and then only about 75g. It's the sacrificial anode process. Since
I have always used battery rods, and a few gouging rods, the cost is not that great. Sure the efficiency is poor. It's the pricipcle of the thing. As
for chlorate, well, that's no real problem with graphite in my opinion.
Mind you, Der Alte would not say no to a nice piece of Pt foil, or a well formed PbO2 anode, if anyone ever achieves the latter. I watch the dfforts
of Dann2 et al. with great interest.
Der Alte.
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12AX7
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NaClO3 forms nearly cubic crystals (they may actually be tetragonal) in certain conditions. In particular, I find them often when cooling slowly near
room temperature in a saline solution.
Tim
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chloric1
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Well I have noticed that there is a pattern. You boil processed electrolyte until cloudy. A powdery deposit forms. THis is the NaCl. I pour off
supernatant fluid to be cooled. ONce cooled the electrolyte deposits crystals that are clear and glassy. These may have cubic speicimens but alsosome
have tetragonal characteristics. I feel it is a learning curve.
@Tim- do you use chromates? If so how do you remove yellow color?
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12AX7
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Washing and recrystallization. Or I suppose NaOH (covert to CrO4(2-)), H2O2 (peroxychromate complex) and acidify (decomposes to Cr(III)) to neutral
(precipitates Cr(OH)3) would be an acceptable alternative.
Fine precipitates (of KClO3) are hard to clean by mere washing and recrystallization; the last batch I handled was just barely perceptibly green when
dried. Oh well, it's only a few ppb of the stuff!
Tim
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12AX7
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After about a week of down time, I replaced the crispy wires to the rectifier (I used wire apparently just a bit too thin for the current) and am now
running on a new anode, a full 1.5" square cross section. As a result, current is higher (60A or so, maybe a smidge more?), which caused those wires
to fail. The rectifier is in a hard-to-reach spot in the cabinet, so I had been putting it off.
Tim
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