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dann2
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Hello,
I cannot get any Potassium Chloride in my neck of the woods for water solteners, only NaCl. I have not looked for a long time though, perhaps things
have changed. I can get lots of fertilizer grade KCl. It's described as 50% K on the outside of the bag, Muriate of Potash is written on the bag too.
@ Gamal. In different countries you get different methods of describing the percentage of K in a fertilizer compound. If you ask for Muriate of
Potash that should get you KCl in an Agricultural store. Of course I don't know what Muriate of Potash in called in the Swedish language!!
It may also be described as 60 - 62% K2O even though there is no O is the compound!
See here:
http://www.ecplaza.net/tradeleads/seller/5480600/potassium_c...
Dissolving two salts into water and seperating them is not a simple matter when the salts have similar solubilities.
What you can do is make Sodium Chlorate (or Perchlorate) and then add the low salt. Most of the K Chlorate (or Perchlorate) will come out of solution
as it has much lower solubility that the other possible salts that are in there.
Dann2
[Edited on 1-5-2009 by dann2]
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Bikemaster
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95% of the water softener is nacl but you have to find the one than sell it. I find mine at home depot, but i read that it is possible to find it at
Sears or at Walmart.
I never try the fertilizer grade but it seem to be ok too.
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hissingnoise
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Fertiliser-grade KCl (Svenska-kaliumklorid) can be dissolved in water, filtered and crystallised.
The purity of the precipitated crystals is sufficient for most purposes. . .
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Gamal
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Thanks for your feedback on KCl and solubility.
I include the following solubility data on KCl and NaCl (from Wikipedia):
Formula 0°C 10°C 20°C 30°C 40°C 60°C 80°C 90° 100°C
KCl 28 31.2 34.2 37.2 40.1 45.8 51.3 53.9 56.3
NaCl 35.7 35.8 35.9 36.1 36.4 37.1 38 38.5 39.2
At room temperature the solubility is quite close, but not at high temp. If I make a solution of 60 g 50/50 KCl/NaCl mix in boiling water, shouldn't
the solution consist of mostly KCl then, at that temp? Then I can just decant it off.
I've been looking for water softeners, using KCl, but it's hard to find by a Google search. I'm also living in a town with very pure water, so I don't
think I'll find it at any shop here.
The main agriculture store, here in Sweden, have replaced there "Kalisalt K 50" with something else they call Kalisalt. I actually bought 25 Kg of it,
without reading on the bag first. It had only 3 % Cl in it. I got my money back as it was clear that it wasn't K 50.
Maybe I have to go to the Yellow Pages and look for farmers and start calling around to get fertiliser-grade KCl 
Sorry for the mess of that table. I couldn't get the columns lined up. Is there any way of using formatted text?
Gamal
[Edited on 1-5-2009 by Gamal]
[Edited on 1-5-2009 by Gamal]
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dann2
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Hello,
Sometimes KCl is used in aquarims.
Looking at the seperate solubilities of the salts in not really going to tell you anything about how to seperate them by fractional crystallization.
You need to look at the mutual solubility graph (system) of the salts in water. Seperating two salts of similarish solubilities is not a simple thing
to put into practice for the home producer. Easy enough if there is a large difference between the solubilites (with the salt you want having lower
solubility) or if there is a large excess of the salt that you wish to obtain as a solid.
There is a book here
http://rs4.rapidshare.com/files/12689034/SolubilitiesOfInorg...
that has mutual solubility info. regarding NaCl and KCl (page 245).
Mutual solubility is a pitb subject it will not be easy to do.
I have read a description of EXACTLY how KCl and NaCl is seperated by fractional crystallization in an industrial set up but I cannot find the
source/ref.
Here is one that almost made me laugh. It involves a saturated solution of saturated brine + suspended Magnetite. Seemingly when you add the mixture
of KCl and NaCl (they won't dissolve as the brine is saturated) the NaCl floats and the KCl sinks!!!!!!!!!!!!
The Magnetite can be got out with a magnet (LOL)
Read for yourself here
Page 74 of this book gives a mutual solubility diagram for KCl and NaCl.
Good luck!
Take a look at US 4248601. It describes getting all the Sodium Chloride out of KCl fertilizer. Not very useful to us though I would think. Look for
other patents on the subject too.
Dann2
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[Edited on 1-5-2009 by dann2]
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quest
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A true “gel” silica gel binder for graphite (or PbO2?) electrodes.
Hi guys,
I was searching the forum for good anode for perchlorate and got up against this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=4177#p...
Tacho made a graphite anode using graphite powder and silica gel as a binder, He also mentioned it didn't show any sign of corrosion when used in
chlorate cell.
Tacho suggested in the thread to try and make a PbO2 anode this way for perchlorate purposes - but I didn't found any evidence for some one trying
this in the forum.
This thread is from 2005 (4 years ago) so I guess this idea didn't worked.
Can some one explain me why the PbO2/SiO2 anode won't work?
SiO2 react with what in the "perchlorate cell"?
thanks,
quest
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Swede
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@dann2 and anyone interested...
I converted the "Lead Dioxide for Dummies" .doc file into an html web page. It's not as pretty, but all the info is there.
Lead Dioxide for Dummies Web Page
I know word documents aren't a popular download. Maybe this will be easier. I hope it works. It seems to, on my computer.
Thanks for the additional pH info. It motivated me to look at my Pharmacia Biotech pH meter a bit more, and with a bit of fiddling, I got the chart
recorder feature to work, so the device will output a Voltage now, proportional to pH, and nicely linear. I'm going to try and incorporate it into my
data collection scheme. It will be worth a pH electrode or two to get a truly accurate representation of all the parameters simultaneously.
@quest - the field of lead dioxide is still wide open in the sense that plating it isn't the ONLY way, certainly. I've got several grades of
boehmite, which we talked about earlier in this thread, and have been trying to think of a way to incorporate it into an anode, as a baked slurry.
The problem is, PbO2 isn't soluble, and most boehmite schemes call for the thermal decomp of a catalyst once the alumina is impregnated. When you buy
(or however you obtain) lead dioxide, it may not be the correct, active form. I believe I lucked into a pound that may work. It is black, looks
exactly like my PbO2 anode, and conducts well.
I'm eventually going to try to create an anode from it in some manner. Anyway, to answer your question, I think it may be possible to mechanically
hold the lead dioxide in some sort of inert binder, but the trick is to make it active, conductive, and immune to the harsh environment it will work
in, and it is a tough task.
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watson.fawkes
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Quote: Originally posted by Swede  |
I know word documents aren't a popular download. Maybe this will be easier. I hope it works. It seems to, on my computer. |
Try out the Office 2000 HTML Filter 2.0 to make the converted HTML even less crufty. Or see Cleaning Word's Nasty HTML, including the comments, for other solutions.
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dann2
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Hello,
The file opens now OK Swede. Will have a good read.
There is nothing beat good old NotePad when it come to doing HTML (simple stuff anyways)!!!!!!!
There is a great 'NotePad' type editor called Notepad++. There is a spel cheacker on it too but it can be a bit of a pain to set up.
@Gamal
Tables are always a pain. If you space them out with dots or - signs they are not too bad.
I added some Lead Nitrate to water to measure density. The density of solutions made from adding 100, 200, 300 and 350 gram amounts of Lead Nitrate
to one liter of water are 1.078, 1.157, 1.236 and 1.275 grams per ml respectively. The density figure of 1.157 represents a solution concentration of
193 grams per liter of Lead Nitrate solution. The region of this figure could be used as a lower limit of Lead Nitrate concentration for good
plating.
The pH of the water droped to 3.1 when I added the Lead Nitrate. I began to add Nitric acid and got the following pH's.
Grams per liter (100%) Nitric acid ----------------------pH
1.1 ------------------------------------------------------1.4
2.2 ------------------------------------------------------1.1
3.3 ------------------------------------------------------1.0
4.4 ------------------------------------------------------0.9
11.6 ------------------------------------------------------0.8
22.1 ------------------------------------------------------0.6
The figure amounts look a but strange as I was weighing small amounts of Nitric acid into a 100ml amount of Lead Nitrate solution (330 grams per
liter).
These figures are not very accurate. The bottom line with the pH's is that it followes (close enough IMO) what you get from theoretically calculated
values like here:
http://www.sensorex.com/support/education/pH_calculator.html
My pH meter is poor and was a bit off when reading a buffer solution of pH 2 but I made an allowance for that.
One other question for plating tanks that we don't know much about is Nitrite build up in the tank. I don't think it lowers plating quality but it
decreases current efficiency which will in turn put off the acid generating calculations as less acid is produced for any amps that go into the
Nitrite Oxidation at the Anode and no Lead is used up.
The calculated Lead compound additons will be off somewhat, how much I don't know.
EDIT: Looking at equation below the acid production is similar to the PbO2 plating acid production but Lead Compound will be off. Perhaps it's not a
big problem?
If we could come up with a simple test to get an idea how much Nitrites are in the tank. Adding Hydrogen Peroxide get rid of them. I have no idea at
what concentration they become a problem.
Attached is a titration for Nitrites.
Anyone know of a simple spot test that would work in a Lead Nitrate tank and give an indication of actual amounts of Nitrites?
Pasted from elsewhere:
_________________________________________________________________________________________________________
Another problem that may accur is lowering of plating efficiency. The problem is caused by Nitrites building up in the tank (see US 2994649).
My theory is that since Nitrite contains less Oxygen than Nitrate, it can be formed at the cathode since reduction takes place there. The equation
could be something like:
NO3- + 2e + 2H+ ===> NO2- + H2O
Now at the anode the oxidation of Nitrite to Nitrate would be competing with the oxidation of Pb2+ to PbO2. The equation would be something like:
NO2- + H2O - 2e -> NO3- + 2H+
Since the potential required for the above process is far lower than that required for the formation of PbO2, current efficiency will drop.
__________________________________________________________________________________________________
Dann2
Attachment: Determination of Nitrites by volumetry.htm (8kB)
This file has been downloaded 8828 times
[Edited on 4-5-2009 by dann2]
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Swede
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dann2, did you measure the densities using a volumetric flask and weighing, or did you use a hydrometer or similar? That may be a useful tool.
Another way to measure Pb++, of course, is to precipitate a small volume of the solution with any soluble sulfate, and weighing the lead sulfate that
drops out.
The pH of my plating tank, at the start, was 0.5, after adding 5g/l HNO3, and I'm reasonably comfortable with that number; and it's not too far off
from what you measured. The actual number isn't all that critical. My thought is this - you could create 2 or 3 small-volume standards (50 to 100ml)
of lead nitrate and HNO3, one at 5 g/l, another at 10, another at 20. Use your pH meter to measure each of them. If the unit is off a tad, you still
have 3 values that will give you a decent idea of the pH of the actual bath relative to your standards.
I think the lead nitrate bath, unlike a chlorate cell, tolerates pH monitoring better, with less danger of probe poisoning.
Nitrites - I'm sure there is a test, but I don't know what it is. Maybe from an aquarium store? Hach makes a strip test, but it may not distinguish
nitrites from nitrates. Current efficiency is much less of a problem with these small plating tanks, vs. a big chlorate cell, from the cost of
electricity point of view. Regardless, I can't see the peroxide hurting anything... may as well use it.
I think the way to go is manual monitoring of pH and manual addition of PbO to a tank that sees modest circulation. Lead Carbonate may be superior in
that it dissolves faster, but litharge is generally cheaper, and it definitely worked for me, only in the sense that it controlled pH.
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dann2
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Hello Swede,
I measured the densities using two hydrometers.
One went from 1.000 to 1.2000. The next one went from 1.200 to 1.300 (g/cc).
The scales I used for the water and Lead Nitrate weigh to one tenth of a gram.
I like the idea of some Lead Nitrate plating bath standards. They would be a useful tool.
I think pH probes do not like heavy metal salts 
I have seen a table of pH probes where 'OK/not OK' for heavy metal salts was a columb in it. Can't find it at this moment in time though. If you are
buying a probe perhaps you need to consider this.
At this link
http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=Sel...
it says:
Silver/Silver Chloride (Ag/AgCl) vs Calomel (Hg/Hg2Cl2)
Ag/AgCl is the most common internal element, suitable for almost all applications [temp limit: 176°F (80°C)]. Hg/Hg2Cl2 is recommended for use in
solutions containing proteins, organics, or heavy metals that could react with silver and clog the reference junction [temp limit: 158°F (70°C)].
See here for more info.
http://www.ph-meter.info/pH-electrode-choosing
Heavy metal will react with Ag/AgCl probes they state.
How much or how quick I have no idea.
Dann2
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Swede
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I have been using a Milwaukee MA911 probe since the beginning. It is double-junction Ag/AgCl. I've used it to test multiple chlorate/perchlorate
cells, and the plating rig, but only with a very quick dip, followed by an immediate rinse, in all cases. I don't even wait the 15 or 20 seconds it
takes to truly settle down, just a few seconds only.
I also took a bottle of storage solution, drilled a hole in the lid, added a grommet, and the probe lives in there... I don't even bother with the
little rubber tip thing. So far it's worked well, and has hardly drifted at all. Every probe eventually drifts, which can be checked with the
standards, and corrected with the calibration methods for the given meter. And they also eventually die when they no longer hold calibration.
I like this probe because the cost is reasonable (about $45 U.S.) yet it seems to be rugged and reliable. I'd buy another one... or, I'd buy one that
is refillable and maintainable. But the "real" lab probes are just ridiculously expensive. I don't know how you can justify a $400 probe that has a
shelf life of 18 to 24 months. It's nuts.
One other option I saw in a Fisher catalogue... narrow-range pH papers. They have a set for 0 to 3, with very clear color changes every 0.5 pH. That
might be a good way to go. Catalog # A981.
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dann2
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Hello,
The pH strips sound good.
I am going to purchase a Nitrite test kit for aquarims from ebay. There are cheap enough. Hopefully they will work in a tank of poison.
I had measured the density of the Lead Nitrate solution for to decide what type of beads would be of a similar density to the solution for stirring
purposes. From this link:
http://www.machinist-materials.com/comparison_table_for_plas... (divide by 0.036126 to convert lbs/inch^3 to g/cc)
the best one is PEEK with a density of 1.3g/cc. Peek in not available but Perspex is available as Acrylic beads on ebay at a density of 1.218g/cc
which will hopefully sink and 'mix' when stirring starts. They will add some nice colour to the plating tank if nothing else. PVC is 1.46g/cc which
may do too.
Anyone any other suggestions as to what could be used? The density of Lead Nitrate solution with 350g Lead Nitrate per liter is 1.28 grams per cc.
@Hashashan (if your are still reading!!). What did you use?
Dann2
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dann2
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Hello Folks,
After a bit of tooing and froeing I worked some stuff for plating LD and posted here.
Whatever it lacks in content is made up for in the colour scheme.
I also attach a spread sheet which may help the hard pressed LD plater work out some stuff.
Feel free to add more calcs etc, you can never have enough of those! (you know).
One last major unknown in the LD plating tank is Nitrite build up. Since US Patent No. 299464 states that a Sodium Nitrite content of 0.1% will
reduce plating CE to 30%, if correct, this is a major issue that needs to be considered. The patent in question is not making Anodes, just plating LD
onto strips of SS (possibly to be ground up as a reagent). They also uses very high current density.
The last (one and only) Ti substrate LD Anode I made had an overall LD plating efficiency of only 62% which I was surprised to find so low when I
worked it out.
Dann2
Attachment: LD_Plating.zip (4kB)
This file has been downloaded 656 times
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watson.fawkes
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Two suggestions.
I always find it useful to see the half-reactions at the anode and cathode separately. It helps me to understand the side reactions that can/will
occur. When you discuss nitrites as a side reaction, you have only one reaction listed (at the anode). Without the other half-reactions to compare
this to, it's a little out of context. I'd also like to see the actual potentials for the half-reactions, since the voltage differences give some idea
about the sensitivity of the process to overpotential.
The other is a pumping suggestion. You don't need to use a balanced, two-sided pump if you rely on an overflow pipe to return effluent from the
neutralizer tank. Just pump in electrolyte into the bottom of that tank and an equal amount will flow out the top. This also suggests the use of a
simple piston and check valve pump, which is easy to calibrate (and keep calibrated) since it has constant displacement per stroke.
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dann2
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Hello,
Half reactions attached.
The board will not let my post my HTML delights so I will (since I am in a THICK mood) attach a file!
Dann2
[Edited on 15-5-2009 by dann2]
Attachment: half reactions.html (934B)
This file has been downloaded 606 times
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Swede
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Dann2, I'm wondering about the nitrites. I don't know about you, but I'm not particularly worried about the CE of the PLATING tank. A typical plate
job starts at a measly 9 amps and drops down from there, for only a day or so. Where CE becomes more important is when you are lashing a big
perchlorate cell with 50 amps for a week.
But if the nitrites produce a LESS VIABLE LD coating, then by all means, it becomes yet another issue among so many that must be controlled.
Again, I'm thinking a small-scale test would be in order. Take 100 ml of used plating solution, and measure the nitrites. Using hydrogen peroxide or
by whatever means, eliminate the nitrite in the small sample; see if it clears. If it does, extrapolate the cleaning method to an operating tank,
under power.
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dann2
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Hello,
I would agree that it's not really an issue about saving power. It may save you some time though and give you a finished Anode quicker which may be an
issue if you are 'baby sitting' a plating tank and adding Lead Compound etc.
I wrote that 'Nitrites give lower quality coats of LD.......' but I have no idea where that has come from. It was a long time ago and I cannot
remember the source. Perhaps Nitrites do not effect coating quality at all. I don't know.
The acid generation in the tank will not be as great as predicted based on current going into cell which may need to be noted.
Perhaps the Nitrites thing is one of the more finer points of the process.
Dann2
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watson.fawkes
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| Quote: Originally posted by Swede | | But if the nitrites produce a LESS VIABLE LD coating, then by all means, it becomes yet another issue among so many that must be controlled.
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I'd guess it's a risk, and dann2 reports it anecdotally. Here are my thoughts on plausible reaction
pathways.
A lone Pb(2+) ion in aqueous solution is ordinarily going to be electrostatically complexed by neutral H2O. Water is a bent molecule and a dipole, so
the oxygen will be nearer to the ion. The mechanics of oxidizing Pb(2+) to PbO2 seems pretty clear: you get a lead ion and two water molecules
adsorbed onto the surface of the electrode and the hydrogens just pop off. As for the nitrite it's also bent and a dipole, so it acts as an alternate
species in the complex. Note, however, that since nitrite is also charged, it's a far stronger complexing species than water. On the other hand,
nitrate is planar, without dipole, and its space charge will keep it from participating in the complex.
An alternate path is that what's adsorbed is a lead ion, one water, and a nitrite. When the lead oxidizes, one of its two oxygen atoms come from the
adsorbed water and the other comes not from the nitrite but from a water molecule that's not adsorbed, that's simply attracted to the net charge of
the lead ion. That other oxygen, not being adsorbed, is also not part of the crystal lattice. So this path generates either a crystal defect or,
worse, a free neutral lead dioxide molecule near the surface that now acts as an alternate nucleation site.
A second alternate is a double oxidation. In this case it would be the nitrite that's adsorbed, with the lead ion attracted to the the nitrogen. The
nitrite acts as an electron conductor, allowing the oxidation of the lead before the nitrite itself also oxidizes. It seems plausible that the
presence of the lead ion inhibits the oxidation of the nitrite, so that the lead must oxidize before the nitrite can. In this case the nitrite is
acting as a kind of "electron catalyst". Whatever the case, the lead dioxide detaches from the nitrite after it forms and never even touches the
crystal lattice. Since this is a sequence of two reactions, not a single one, there's no need for overpotential to have it happen.
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dann2
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Hello,
There is a paper attached on LD Plating reactions. Thought you might be interested.
This was posted before somewhere or other on Sci.Mad before.
Cheers, Dann2
Attachment: alpha or beta for acid bath.pdf (94kB)
This file has been downloaded 1074 times
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Swede
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Interesting paper, lots of good info. The authors used H2SO4 + H2O2 to clean the substrate prior to plating! Now I need to see what this vigorous
cleaning will do to a sample of the eBay MMO. If the MMO coating can shrug off the Caro's Acid, it'd certainly be an optimum way to clean them prior
to plating, rather than boiling in a surfactant, or similar.
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Swede
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I tried cleaning a small sample of the cheap eBay MMO with Caro's acid, as strong as I could make it, using 1:1 sulfuric plus 35% peroxide.
The original sample had some brown "smut" overlaying portions of the darker MMO. From previous tests, this MMO is excellent for chlorate production,
despite the smut and scratches.
The before and after pics, after perhaps 3 minutes immersion:
Before:
After:
The acid did not seem to do much. While the MMO coating itself seemed relatively impervious to the acid/peroxide mix, the smut was not removed, and
if anything, it increased slightly. I have no idea what the brown stuff is, but if the use of MMO under lead dioxide bears fruit as an anode, I'd
start the procedure with a new, different anode, rather than the eBay stuff so many of us have. The cleaning and prep of the anode is critical prior
to plating, and you may as well start with stuff that is new and clean to begin with.
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Gamal
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Doesn't the H2SO4 turn the MMO coating into sulfate as it's an (mixed) oxide? I haven't checked it up, just a though. Anyhow, I think we have to take
into concideration what stuff we use on MMO as it's not just cleaning a metal surface.
/Gamal
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jpsmith123
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Hello Quest,
I would venture to say that no one has tried it. If you have the time, work space and the ingredients, it's probably worth an experiment or two to
check it out.
I think if someone comes up with a viable alternative to platinum and/or electroplated PbO2-over-MMO(or SnO2)-over-valve-metal...well who knows, maybe
they could make some money.
| Quote: Originally posted by quest | Hi guys,
I was searching the forum for good anode for perchlorate and got up against this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=4177#p...
Tacho made a graphite anode using graphite powder and silica gel as a binder, He also mentioned it didn't show any sign of corrosion when used in
chlorate cell.
Tacho suggested in the thread to try and make a PbO2 anode this way for perchlorate purposes - but I didn't found any evidence for some one trying
this in the forum.
This thread is from 2005 (4 years ago) so I guess this idea didn't worked.
Can some one explain me why the PbO2/SiO2 anode won't work?
SiO2 react with what in the "perchlorate cell"?
thanks,
quest |
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Aqua_Fortis_100%
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Titanium cathode embrittlement
Hello Folks
Maybe this is not the best place to talk this, but is (per)chlorate related and I always try to not creat a new (repeated issue) thread..
The great friend Dann2 kindly provided me a ebay anode and a thin Ti foil (grade 1) cathode among other itens for clean (per)chlorate production, as
all would be next to impossible to obtain in my country.
Weeks ago I started to use a non-controlled pH cell with ebay MMO and a piece of the Ti sheet , KCl electrolyte and a PC-PSU..
After some days running, I found that the cathode was so brittle that when I tried to remove it from the lid, some of it breaked apart.
What is happening? Did this happened to anyone here?
I was under the impression that Ti as cathode would last forever in (per)chlorate cells; maybe last only on chemical view, not mechanically..
The cathode loose its shiny surface and was with some white spots on it (TiO2?)..
Many metals suffer from hydrogen embrittlement, maybe this happened with Ti.. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...
Do the embrittlement occur with very easy breaking only with too thin Ti pieces?
BTW, I agree with Swede and all other people that there is nothing esle better than MMO to chlorate production without mess.
Thanks!
[Edited on 13-6-2009 by Aqua_Fortis_100%]
[Edited on 13-6-2009 by Aqua_Fortis_100%]
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