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Swede
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How about a chamber in one corner of the plating tank, loaded with litharge... one wall of the chamber has a series of holes in it, and a sliding,
mating wall that will allow a variable exposure of the chamber's contents to the rest of the tank? I am a fan of agitation and stirring, and with the
main plating tank liquor in motion, you'd have diffusion between the two components.
Or maybe an "off-line" pool chlorinator. Now you are back to two tanks, but the pool chlorinators are well built, have a variable flow valve, and are
designed to trickle liquid through (and interact with) the contents, at a slow rate.
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Rosco Bodine
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That crock pot teeter totter arrangement is sounding better by the minute, huh? It's the whole tidal motion thing I tell you ....kind of like a
respiration induced by
an iron lung, or gill ....in with the lower pH and out with the higher pH .....man it's like the scales of pH justice 
And for so long folks have been told to get the lead out,
....hold the phone...here's to seeing how you put the lead back in 
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Swede
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Guys, I am having difficulty in determining the mechanism whereby potassium metabusulfite (K2S2O5) is used to clean up traces of chlorate from a
perchlorate batch. This is a partial repost of something I put on the APC web site:
APC Posting:
The metabisulphite creates,in an acid environment, SO2 gas, which is the reducing agent:
K2S2O5 + 2 H+ --> 2 K+ + H2O + 2 SO2
As for the actual reduction, this unbalanced equation is my best guess:
2K+ + 2SO2 + KClO3- --> K2SO4 + KCl
Does anyone know what byproducts are left behind from this reduction? The byproducts determine the next step in the purification process.
Finally, an interesting picture of the series of tests I ran to determine the point at which the perchlorate was "clean."
Comments, tips are appreciated. This (the cleanup of perc) is an important part of the overall proccess. The use of an SO2 generator, bubbled
through the liquor, would introduce less contaminants, and make post-processing easier.
[Edited on 17-4-2009 by Swede]
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dann2
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Hello,
This overall reaction was given to me long time ago (for Na).
3Na<SMALL>2</SMALL>S<SMALL>2</SMALL>O<SMALL>5</SMALL> + H<SMALL>2</SMALL>O +
2NaClO<SMALL>3</SMALL> => 3Na<SMALL>2</SMALL>SO<SMALL>4</SMALL> +
3H<SMALL>2</SMALL>SO<SMALL>4</SMALL> + 2NaCl<br>
Taken from http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
Dann2
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Swede
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Thanks, Dann2, I saw that on your site AFTER I had posted. SO the remnants of the cleanup are sulfate, salt, and acid. Once again, using potassium
salts, I'm faced with solubility issues. KCl is decently soluble, potassium sulfate is more soluble than perchlorate, but not as much as I'd like.
Still need to eliminate those pesky salts. I'm thinking a large batch would be best - as soon as it tests clean, drop the temp, gather the xtals,
then recrystallize, harvesting the perc at about 5 to 10 degrees C. I'd guess that would get rid of 90% of the sulfate and chloride. But the remnant
liquor, which you'd normally like to recycle into the next cell, is now rich in sulfate. How to get rid of that? Otherwise you are looking at more
losses of perc than one would want.
Bubbling SO2 gas vs. adding bisulfite wouldn't make it much better. You'd still end up with the same reduction products in the product.
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dann2
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Hello Swede,
Some stuff on Sulphate solubilities here:
http://www.chemguide.co.uk/inorganic/group2/solubility.html
If you had some Lead Perchlorate (should I put the roll eyes here???). The vast majority of the Lead will come out as Sulphate so long as you stop
adding the Lead Perchlorate in time. It's not one I would be a hurry to implement myself but it would work.
What other elements have very insoluble Sulphates?
If one had a supply of Sr or Ba Perchlorate for the job that would be great. It's more and more work though.
Perhaps Ba Chloride (Ba Carbonate from ceramics store + HCl)would fit the bill. You will be swopping Sulphate contamination for Chloride contamination
when you add the Ba Chloride to your solution to ppt the Sulphate (as Ba Sulphate).
Regarding the amounts of Bisulphate you have to use to get rid of residual Chlorate, how much Chlorate have you per liter do you know. You could try
an experiment whereby you add a known amout of Chlorate to clean water and see how much Bisulphate it takes to give a clear test with the
N-Phenyl...acid.
Dann2
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Bikemaster
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Why did you whan to use bisulphate to get rid of chlorate??? It seem to be better with hcl because you don't get other component in your mix.
2KClO3 + 4HCl --> 2KCl + 2H2O + 2ClO2 + Cl2
KClO4 is supose to resist.
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Sedit
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I know this threed is more geared to perchlorate anodes but I have been experimenting with persulfate cells recently and the patant that I have been
going off of suggest either platinum or carbon. Since I dont have platinum I used carbon which was promply eaten away after running a low voltate low
current over night. Im assuming that an electrode that would work with something as harsh as perchlorates would work with persulfates but I was
woundering if there was anything other that can be used also for persulfates?
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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hashashan
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Never heard of carbon, I always thought that Pt is the only anode that can whithstand the harsh conditions of a persulfate cell
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Swede
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One of the resons I went with bisulfite is the hope that the chlorate contamination would be very low, and that very small amounts of bisulfite would
be needed. HCl does work, but the chlorine dioxide has me a bit worried. There's a difference between cleaning up a 20 gram test sample with HCl,
and trying to clean up 2 or 3 kilos of dirty perc.
Are there any other reducing agents that might do the trick? I'm fairly certain I read somewhere that bisulfites are what the big factories use, and
when the big boys use (or do) something, it usually works well. I think the technique is important... maximum exposure of the SO2 gas to the hot
liquor.
The ideal reducing agent would attack the chlorate preferentially, and then be boiled off as a non-toxic, hopefully non-irritant gas. There will
always be KCl left over, but that is easily removed in a single recrystallization op.
I've got my cleaned sample... now I need to determine how much sulphate and chloride are in there. The chloride is easy - I've got the titration
strips. How about the sulphate? I could add an excess of lead nitrate, then weigh the sulphate ppt. That will give me quantitative results. If
they are low enough, then there may not be a need to do anything further, and aqueous bisulfite additions may be all that's needed.
It is probably pretty easy to get wrapped up in trying to create 99.999% perchlorate, when 98.5%, with residual chloride and sulphate, is perfectly
acceptable for pyrotechnic use.
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Sedit
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@hashashan
Heres the patant as followed aside from a few differences. It states that carbon anode can be used but clearly it is not feasible because I was left
with no electrode and a carbon slurry anolyte solution after running maybe 10 hours.
Attachment: persulfate.pdf (47kB)
This file has been downloaded 917 times
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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dann2
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Hello,
Some info. at this link on testing Pt, PbO2 and Graphite Anodes for Persulphate making.
http://www.journalarchive.jst.go.jp/jnlpdf.php?cdjournal=bcs...
There are parts one and two if you dig them out. May be worth a read.
I think you are stuck with Pt or PbO2.
Dann2
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dann2
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@Swede
I think the large producers can get very pure Perchlorate from continously operated crystallizers.
The folks that used to make Ammonium Perchlorate in Nevada were able to use their Sodium Perchlorate for making Ammonium Perchlorate directly from
the NaPerk crystallizer without any chemical destruction of Chlorate (according to stuff I have read).
The one off batch thing is a different beast.
Dann2
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Bikemaster
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I know than is produce a lot of ClO2 but, if it is done outside it will be correct,( will be a good idea to wear a gas mask and
glasses). I read something than say than ClO2 can be compare to H2, maby more toxic but ClO2 is a explosive gaz... but if it is done outsive, it will
not be too worst for your
health.
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dann2
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Hello,
I posted some stuff on Persulphates and testing Anodes but it disappeared.
Better luck this time!
I think you are stuck with Pt and PbO2 for making Persulphate.
Magnetite might do?? I always had an interest in Magnetite since the strating material is so easy to get and non-toxic but the Anodes are not too
easy to make. Very high temperature needed to melt the stuff.
Dann2
Attachment: Persulphate.zip (879kB)
This file has been downloaded 820 times
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Swede
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Success in cleaning up perchlorate and purifying it with metabisulfite. As a continuation of my post above, I recrystallized the cleaned perc and
harvested at maybe 5 degrees C. Yield from the original 20g was 17.62 grams of potassium perchlorate.
The tests for chloride consisted of
1) A Hach chloride titration strip - zero.
2) Several drops of strong silver nitrate. The sample remained clear. The silver nitrate test is sensitive, and yielded a nearly opaque white from
tap water. The two are shown side by side, perchlorate on the left, tap water on the right, with added silver nitrate. The white coloration in the
left test tube is reflection from the right test tube on a black background. The solution is quite clear.
Conclusion: negligible chloride.
Next, sulfate. Saturated lead nitrate was added to another sample. Insoluble lead sulphate should form if there was significant potassium sulfate in
the perchlorate. Again, I noticed zero precipitation; the solution remained clear and bright.
If there is any sulfate in there, it is low enough to ignore.
Here is the cleanup procedure for POTASSIUM perchlorate that I think will work to reduce residual chlorate, and eliminate and reduction byproducts...
1) Calculate the amount of water needed to dissolve the perchlorate at 100 degrees; use 50% more water. 200 grams of potassium perchlorate would
require 1.5 liters. Heat, but do not quite boil, the potassium perchlorate solution until all of the perc has dissolved.
2) Prepare a solution that contains 10% by weight potassium metabisulfite, relative to the amount of perchlorate you wish to clean. In other words, if
you have 500 grams of perchlorate, start with 50 grams of potassium metabisulfite. This is cheaply obtained from home brew shops, and similar.
3) Add enough HCl to gently acidify the perchlorate solution, perhaps 15 drops per liter. Using a pipette, and with stirring, gradually add 1/2 of the
potassium metabisulfite solution to the perchlorate. Allow it to stand for several minutes with continued stirring. Test the solution for chlorate. If
still dirty, add additional metabisulfite.
4) Once clean, the solution needs to be neutralized, or made very slightly basic. The caustic of choice is KOH. Since the reduction byproducts are
acidic, it requires more base on a Normal basis than the initial added HCl would indicate. Slowly add saturated KOH, dropwise, to the solution, and
test with pH paper or a probe. When nearing neutral, it doesn't take much additional base to overshoot, so use caution. If you make it too basic, add
a drop or two of HCl to bring it back to neutral.
5) Boil the solution down until the quantity of water is equivalent to the necessary mass of water for the amount of perchlorate used. Potassium
Perchlorate dissolves at a rate of 200 to 220 grams per liter at 100 degrees C. An easy way to do this is to boil down until the very first crystals
appear, and from there, allow it to first slowly cool to room temp, then refrigerate. Harvest the perchlorate by the usual means (decant + filtration)
when the solution is at approximately 5 degrees C. Remaining potassium chloride and potassium sulfate remain dissolved, and are discarded. Wash the
perchlorate with ice water and then cold ethanol. Spread the perchlorate out to dry, then ball mill to the desired consistency.
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dann2
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Hello,
Swede. That's not Pyro grade K Perk. you have there. It sounds more like research grade!
It's amazing that no Chloride is showing up in it.
Regarding what you asked over on APC about making Ammonium Perk from K. Perk, you could make Perchloric acid from the K Perk + HCl acid (I think,
perhaps someone else can comment on this).
Once you have Perk acid you can go anywhere with the Carbonate, Nitrate or Chloride of the compound that you wish to work with. See here for some
info.
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
Never done it myself. Perk. acid is very nasty stuff.
My 'Holy Grail', pH controlled cell, is at an end. The Chlorate level is below 10 grams per liter. I am going to let it run some more just to see how
low the Chlorate will go. It took the cell running at about 5 amps (2.3 liter cell), 24 hours to reduce the Chlorate level from 22 gpl to 10 grams per
liter (yesterday), which is approx. 10%CE. I like to think of the LD Anode at this stage of the cell run as 'electrically operated Bisulphate on
Titanium'. I like the waste product too, more Perchlorate!
There was no additives (NaF etc) put into the cell untill it was well into the Perchlorate stage. I should not have added any but I mistakenly
thought that the CE during the Perchlorate stage was very very low (7%) but this was a miscalculation on my part. I added 6 grams NaF to try and get a
greater CE but there seems to have been no need as I subsequently discovered. It probably helped a bit no doubt but I would have rathered had a
'green' cell the whole way through. (It also is getting the blame for Ti substrate erosion).
The Anode is getting very weary looking but there was very little Lead metal appearing on the Cathodes on this run. The Alpha LD underlayer was
exposed on an area for a time but wore off.
The CE during the main Chlorate stage of the cell peaked at 80%
The CE during the main Perchlorate stage peaked at 55%.
The CE during the Chlorate stage overall was 52%
The CE during the Perchlorate stage (Chlorate going to Perchlorate) was 25%
The overall CE (end of cell run deemed to be at 10 grams per liter Chlorate) was 42.6%. Industry gets about 64% CE for this type of operation BTW.
Chloride level in the cell at very end of run was 13 grams per liter. But then I am wondering is the Flouride I have added interfering with my
Chloride titration using Silver Nitrate and K Chromate as indicator.??? I am also adding HCl acid at a rate of 20 grams 12% stuff per day.
When deciding what was the 'Chlorate stage' and the 'Perchlorate stage' a part of the cell run where Perchlorate was first discovered was omitted in
the CE Calculations.
I let the cell run an extra day (119 ah) after the point where Chlorate was at 10 grams per liter and the Chlorate level decreased to 5 grams per
liter, CE = 4.2%.
The cell was then stopped. There was a large amount of fluffy grey stuff on the cell bottom. I looked at the Anode and there is a large amount of
erosion of the Ti substrate. There are a few deep erosion streeks like river erosion going up the Anode. I am blaming the Flouride for this but I am
not 100% sure. Never seen it before and it definitely was not there before I added the F. The Flouride I have is ebay grade. When I was dissolving it
in water there seemed to be some of it that would not dissolve. Will post pictures of Anode.
The acid demands of the cell during the Chlorate stage were somewhat less that a Graphite/MMO Anode cell (pH ~ 6.5 - 7.0) at 0.09 ml per hour per amp
(12% HCl) but the cell never reached a point where acid could be stopped. Small amounts were still needed during the latter days of the Chlorate
stage. When the Cell entered the Perchlorate stage the acid demand was up to approximately 0.42 ml per hour per amp (pH was kept at around 7.4 at
this rate of addition). If acid was turned off the pH climbed to 10.8 within a few hours. When I added the 6 grams of NaF the acid demand decreased to
0.3 ml per hour per amp. As the cell ran the acid demand decreased to 0.1 ml per hour per amp and this was maintained untill the end. This rate
towards the end kept the cell between 6 and 7.
I don't know why Perchlorate cells are pH controlled. Schumachers book states that they are but studies have also said that CE is independent of pH.
The CE is disappointingly low. I am going to blame the large Cathodes. (have to blame something). Since approximately half the surface area of this
Anode has it's LD wore off and the Cathode are still the same size as they were when it was new this means that they are far far too big. I need to
cover the backs of them and 50% of the front of them (since half of the Anode surface area at the bottom of the Anode is gone) with plastic. This
may/may not make a difference. Also the Cathode are officially Titanium, but in reality they are Lead as they have a coating of Lead (I presume) on
them. This Lead covering is very fluffy which makes the effective surface area even bigger.
Can anyone suggest what the catalytic activity of Lead versus Ti is for the reduction of Hypochlorite, Chlorate and Perchlorate back into Chloride
and Chlorate???
I can safely say that I HNGAFC. (have not got a *#&&^%? clue).
There is some Ozone smell coming from the cell but not as much as the last run. This Anode has now clocked up over 4.5 months of run time in cells. I
reckon there is one more 'Holy Grail' run (with pH controll) left in it. The Cathodes will be getting a trimming this time. The only disadvantage in
using small Cathodes, so long at the small Cathode area surrounds the Anode is a sensibly manner, that I know off is a higher Voltage accross the
cell. Less power efficiency, and when you are using a hot resistor to drop Voltage anyways that's not a disadvantage at all.
I also added another number to your simple CE calculations Swede.
Na Chloride all the way to Perchlorate:
CE = 175.10 * Weight/Ah
Dann2
[Edited on 27-4-2009 by dann2]
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dann2
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Hello,
This is a (very poor) photo of the eroded Anode. The picture shows both sides of the Anode. A fairly large area of Alpha Lead Dioxide is visible on
one side of the Anode and seems to be holding up quite well. It is fractions of a mm thick. The Beta thats left can be seen on both sides at the top
of the Anode. There are lots of cracks in it. The erosion of the Ti is showing up as two streaks on one side of the Anode mostly. The streaks are
quite deep. There is erosion of Ti at the very top of the Anode too above the Lead Dioxide just below the lid.
There is also a picture of the Anode when it was approx. half way through the run.
Dann2
[Edited on 27-4-2009 by dann2]
 
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Swede
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Dann2, excellent postings as usual. I think you have done more than anyone that I am aware of in increasing the body of knowledge of home
(per)chlorate production.
Perchloric acid: I decided long ago not to even mess with it. The salts, definitely, but there are too many unusual attributes of the acid to make
it something you'd want to mess with in quantity. Fume hoods exploding, that sort of thing! Ammonium Perchlorate is one of the cheapest percs you
can buy, and of course it is easily produced from the sodium salt so long as all chlorates are cleaned out first. For pyrotechnics, at least, I'd
guess potassium is used for 85% of the comps, and ammonium is the remainder. There is an AP blue I want to try, but it can wait.
| Quote: |
Chloride level in the cell at very end of run was 13 grams per liter. But then I am wondering is the Flouride I have added interfering with my
Chloride titration using Silver Nitrate and K Chromate as indicator.??? I am also adding HCl acid at a rate of 20 grams 12% stuff per day.
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This seems a bit high for chloride, but I am not experienced with this particular chloride titration method. Just to be absolutely clear, you are
running all the way from chloride to perchlorate with this particular cell?
I have never seen erosion of bare Ti on an anode, even at high current densities. Do you know what particular alloy, if any, was the Ti? I switched
to commercially pure early on, mainly because it was easier to work with physically, but also because of the chemistry. Aluminum and vanadium... I
don't know how protected those would be by oxide formation.
It does look like the surface area of your cathode increased, perhaps by as much as 4X (just a guess). The action of NaF on these electrodes is so
difficult to even take a guess at. All we have to go on is industry, and the chemistry that takes place in our cells is a bit different from what
takes place in a serious industrial setup. I have yet to add anything (dichromate or NaF) to a cell, only because I don't want to worry about the
residuals. I'd personally rather live with lower CE than deal with contaminants, especially the dichromate.
Thank you for the addition to the CE "library." So far we have:
W = Weight of yield, in grams
E = Efficiency
AH = Ampere-Hours used
For Potassium Chlorate Production from KCl
E = (131.32 * W) / AH
For Potassium Perchlorate Production from KClO3
E = (38.42 * W) / AH
For Sodium Perchlorate from NaCl:
E = (175.10 * W)/Ah
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dann2
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Hello,
Actually I had posted your original quick and easy CE calculations at the bottom of a run time page and added two more. There are now five in total. I
find myself always using them.
Process Formula for CE in %
Na Chloride to Chlorate 151.08 * Weight/Ah
Na Chlorate to Perchlorate 43.78 * Weight/Ah
K Chloride to Chlorate 131.22 * Weight/Ah
K Chlorate to Perchlorate 38.69 * Weight/Ah
Na Chloride to Perchlorate 175.10 * Weight/Ah
The cell above was run all the way from Sodium Chloride (300 grams per liter) to Sodium Perchlorate without stopping. I intended the cell to be
'green' but I (a mistake really) added NaF approx. one third way into the actual Perchlorate stage. This process (Chloride to Perk)was not done much
in industry and IMO it was only done way back when power was cheap as new hydrodams were being put up in the Nevada area. This may not be correct.
They uses NaF or Persulphate and Anodes were PbO2 on Graphite. I think F is out when using Ti substrate Anode of any sort let they be MMO or whatever
in long term productin.
According to US Patent 7,250,144 (July 2007) F damages Chlorate Anodes. Since this is a modern patent the Anode are MMO. Perhaps it's just the coating
or perhaps the substrate gets damaged or both.
Link to scientific study where they got 55-62% CE.
http://www.geocities.com/lllwolly/further/jes1976.html
The 42.6% CE (Chloride to Perk) that I got is not 100 miles from what it is sensible to expect.
NaF seems to make a big difference to CE according to the attached picture.
Persulphate is as good and better I have read somewhere else...........
The Chloride titration I am using is here:
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
The Grade of Ti I am using is Grade one. No Alloying elements, pure Ti.
The Anode was a first for me for PbO2 on Ti and is, at the end of the day, only an experimental Anode to see how the Ti + Tin Oxide + PbO2 system
manufactured in a low grade, garage plating set up would perform. It had a very thin coating at the bottom (0.95mm think) + ceramic particles, which
I had in the plating bath for to keep bubbles swept off the forming Anode, were imbedded in the coating and (IMO) did not help matters as far as
erosion is concerned. (Repeating myself here).
I think an Anode with a proper thickness of coating and perhaps better control of the acid produced when coating will be a long term winner.
There is an article here that condemns thin LD Anodes for Perk production from Chlorate. They are massive Anodes though, grown on Ta wire. They claim
the thin one's erode and the thick Anodes do not erode, sounds strange.
http://www.geocities.com/lllwolly/further/jesmar58/jesmar58....
Dann2
[Edited on 28-4-2009 by dann2]
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Swede
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I realize it's taken forever, but I've finally gotten my data collection system together, and ready to run. Most of the time was spent with fiddly
things, like mounting current shunts on the rear of my two power supplies, working with the shielded cabling, and massaging the software. With data
collection ready to go, I plan on making a small (4 liter) test cell for the first few runs.
The first run will consist of MMO and a starting electrolyte of pure KCl, no cheating by adding "used" liquor. While technically not pH controlled, I
plan on using my timer and dosing pump to keep the pH as close as possible to 6.8. I will be taking periodic samples, so I will be able to overlay
chloride concentration when all is complete. The automated data collection will consist of voltage, current, and temperature. I would LOVE to add pH
to the system, but faced with probe poisoning, I don't know that it will ever be practical for a small home setup. I went so far as to buy an old pH
meter off of eBay that had, on the back, a "chart recorder" terminal that is supposed to output a voltage proportional to the pH, but unfortunately,
while the meter works, the chart recorder terminals show no voltage whatsoever. Bummer. I would have sacrificed a cheap pH probe just to see if it
(the probe) survived, and to get the data.
The next run will be my better lead dioxide anode, starting with chlorate, rather than chloride. It should be interesting.
Let's talk acid once more. pH control, manual or otherwise, is important, and efficiencies go way up at the proper pH; anodes are safer, too, I
believe. In an older post I wrote
| Quote: | | HCl: With "T-Cell Jr" (18 to 20 liter potassium chloride--> chlorate) I had the dosing timer set up to turn on 6 times per day for one minute, and
each cycle of the dosing pump delivered 12-15 ml, so somewhere around 100 ml per day of 15% acid worked. I could probably have added more, the pH was
more often than not around 7.5 rather than 6.8, but I was very pleased at the stability. Once it was "forced" down to near neutral, there was no
tendency to rapidly climb; periodic acid dosing as a concept works, and I believe it is a good alternative to full pH control with an immersed probe,
with its associated probe poisoning problems. |
Then dann2 replied:
| Quote: | Thanks for the acid info. I was looking for it actually.
You seem to have been able to control cell with a very small amount of acid compared to my (much smaller) 5 amp, 2 liter cells.
Your cell needed 0.104ml 12% HCl per hour per amp to keep pH about 7.5.
My cell needs 0.42 ml 12% HCl per hour per amp to keep pH at 6.8.
About 0.39 ml per hour per amp keeps pH at approx. 7.5.
(I converted your figure to 12% acid as that is what I have, from the hardware store). |
dann2, I remember in the original exchange here that I made a mistake; my acid was not 15%, it was 21%, so my cell required more than 0.104ml 12% HCl
/ hour / amp. Do you remember the industrial number of HCl consumed per ton of chlroate produced? I would like to do a bit of math and see if I can
create a simpler equation to solve for needed acid per amp, with a given CE. We know that industry typically operates at 96%+ CE, so given those
numbers, we should be able to create an equation... plug in known or predicted CE, amperage, and from that, derive an HCl dosing schedule.
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Swede
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I forgot: In a desperate attempt to keep organized, and keep my own documents and experiments up to date, I decided to incorporate dann2's excellent
observations on the evolution of nitric acid in my "Lead Dioxide Plating for Dummies." I am convinced that HNO3 control is over half the battle to
make a good anode. I also removed all references to Bismuth salts as an additive to a plating tank. dann2, if you have problems with this and want
them removed, let me know. My goal from the outset with this document was to create a resource that would combine all of the patents, show my own
experiments, and provide the info in an accessible manner. It is a doc for all.
It is up to 1.1 megabytes, and 31 pages. As always, it can be found here:
http://www.5bears.com/ld/ldfd01.doc
[Edited on 30-4-2009 by Swede]
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dann2
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Hello Swede,
The figure of 0.42ml per hour per amp to keep pH at approx. 6.8 was posted as soon as my cell was started. This figure is too high, as you know the
cell demands more acid at the start of its run. Later it settled down to a more 'normal' amount of 0.13ml/h/a.
My final figures for acid going into cells is here (near the bottom). There is some info. from industrial setup's there too.
I will correct the 15% versus 21% error and also state that you were using MMO.
Definitely a bummer about the pH charter. Perhaps it would be worth taking a look inside as it may be a simple problem.
Perhaps you would need to put a load on the output to get it to work. It may not function with only a high impedence volt meter connected (guess).
The .doc on LD plating will not open correctly for me. The last version opened OK. Perhaps you have used a different/newer version of Word to write it
up?
One more 2 cents on Flouride/Chloride Ti erosion.
This link talks of pH being a factor in Ti erosion in F + Cl (ion) solutions.
This last cell (with Ti substrate erosion) was conducted with the pH held at approx. 6.7 at the end of the Perchlorate stage which was a first for me
with LD. So maybe this might help explain the erosion.
Bottom line is (IMO) F is out for Ti substrate anything.
Perhaps we should look at Persulphate as the 'green man's' additive. Perhaps it makes SFA difference anyways to CE.
Dann2
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Gamal
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I have some problem getting cheep KCl here in Sweden. I have tried to get the stuff they use in the agree culture but it's hard to get if you're not
in that business.
The only thing I can get right now is what I can buy at the super market, called mineral salt or sodium reduced salt, and it's not cheep. It's a
mixture of 50 % NaCl and 50 % KCl. I guess I have to start out with a small batch.
I have been searching information about solubility relations in solutions with two or more salts solved, with bad result.
What happens if I make a saturated solution of this mixed salt. will I get a solution with mixed salt or will all of the most soluble salt go into
solution first and then the least soluble salt until it's saturated? If it's the last, I can just measure the right amount of water to get only the
KCl solved and decant it of.
My point, of course, is to crystallize the KCl out of the solution.
Gamal
[Edited on 1-5-2009 by Gamal]
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Bikemaster
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Go see for "water softener"
it is sell as no sodium salt or potassium chloride
13$ for 20kg
[Edited on 1-5-2009 by Bikemaster]
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