Sciencemadness Discussion Board - Ammonium perchlorate without DIY anodes?

Ammonium perchlorate without DIY anodes?

Pages: 1 2

Fulmen - 7-12-2014 at 07:06

I'm looking at the possibility of making AP, but I do not want to mess with making my own PbO2-anodes. And since they cannot be bought easily, I will have to find something else.
Although there is a lot of info out there it's not easy to find conclusive answers, so here's a few questions:
MMO (which ones) will work for chlorates, but not perc. Right? And platinized Ti can work for perc, but only in low-chloride conditions. Right?

This presents new problems, as it's not that straightforward to separate NaCl from NaClO3. And since MMO can't handle ClO4 I can't run the cell until all Cl is converted.
Am I barking up the wrong three or is this doable?

deltaH - 7-12-2014 at 07:18

Ruthenium oxide based MMO electrodes have the highest efficiency for generating chlorine, while iridium oxide based MMO are recommended for water electrolysis (that swear word around here, the HHO cell

), AFAIK.

I do not know much about making perchlorates electrolytically, but it's news to me that you can't use MMO for perchlorates, why?

So since the electrolysis proceeds by generating chlorine at the anode, I'd say go with ruthenium oxide MMO electrodes, unless suggested otherwise by the many users with experience on such cells here

BTW, I recall a long while back looking at a table of overpotentials for various electrodes and half reaction occurring on them. The overpotentials for hydrogen production at the cathode are quite large for many electrodes, so perhaps if you want to drive your cell hard and minimise heating, using a platinised cathode would work best... provided money is no object

[Edited on 7-12-2014 by deltaH]

Hennig Brand - 7-12-2014 at 07:42

Platinum anodes work great for making perchlorates. They will just need replacement more often if abused.

From: CHLORATES AND PERCHLORATES
THEIR MANUFACTURE, PROPERTIES AND USES
Prepared by
Department of Chemistry and Chemical Engineering
Southwest Research Institute

In the section on Crystallizers (pg. 56):

"In the operation of a typical crystallizer, fed from the chlorate
cells at 104F, containing, for example, 41.0% NaClO3, 9.3% NaCl and the
remainder water, enters the first tank at a rate of 14,450 lb/hr. The
mother liquor which is now cooled to 20F is discharged at a rate of
11,950 lb/hr from the centrifuge for recycling through the first heat
exchanger back to the brine preparation tank. It now contains 28.8%
NaCl03, 11.3% NaCl and the remainder water. The yield is thus 2500 lb/hr
of NaClO3 or 30 ton/day."

If you can find Dann2's site, he had all kinds of phase diagrams and there were some good ones for the sodium chlorate-sodium chloride in water system from what I remember. IIRC the solubility of sodium chloride changes very little with temperature change, but the solubility of sodium chlorate does.

I also found a few PDFs here which should help you.
http://www.utahpyro.org/compositions/

Attachment: Preparing Chlorates.pdf (115kB)
This file has been downloaded 1330 times

Attachment: Preparing Perchlorates.pdf (60kB)
This file has been downloaded 1307 times

Attachment: Analysis of Perchlorates.pdf (48kB)
This file has been downloaded 980 times

I don't want to annoy Dann2, but I made PDFs of a lot of his site material a while ago. His site is, or was, a very good resource. Here is the page on separating sodium chlorate from the electrolyte.

Attachment: Removal of Sodium Chlorate.pdf (233kB)
This file has been downloaded 1593 times

[Edited on 7-12-2014 by Hennig Brand]

Bert - 7-12-2014 at 08:02

As the OP didn't reference his statements-

And we have been here before-

I am going to merge this with an existing thread.

I would prefer that OP select from the MANY relevant threads-

BTW, this popped out at me while scanning those existing threads...

http://www.sciencemadness.org/talk/files.php?pid=140798&...

[Edited on 7-12-2014 by Bert]

jock88 - 7-12-2014 at 12:59

Dann2's page is now here

http://oxidizing.typhoonguitars.com/

Some of the stuff of the http://www.utahpyro.org/compositions/ site (pasted below) is nonsence.

*start of quote*
...................
.....................

Electrode materials for perchlorate manufacture.

DSA: DSA stands for Dimensionally Stable Anode. This is the common term used to
refer to anodes consisting of a layer of noble metal oxides (usually RuO2 and TiO2)
coated onto a substrate, usually titanium. This type of anode is finding increased use in
industrial cells because of its comparatively low cost when compared to platinum and its
resistance to corrosion. The chemicals required to manufacture these anodes are
expensive and difficult to handle. However, if the chemicals can be obtained and suitable
equipment is available, the procedure to make the anode seems fairly straightforward and
may be an option. For the preparation of these, the reader is referenced to the literature.
Again, I'd be most interested in anyone’s experiences with this type of anode.
Magnetite: This material has found use in industry in the past, but is rarely used
nowadays due to its relatively high corrosion rate and low efficiency for perchlorate
manufacture. The anodes are made by melting and casting FeO.Fe2O3 into the required
anode shapes. I have little literature available on this material, so it is not further
discussed here. *end of quote*

Fulmen - 7-12-2014 at 13:36

My apologies for bad search-fu. I will try to do better in the future.

Also, thanks for all the data, I'll be sure to read them thoroughly before asking more stupid questions. I figured I would have to precipitate out the NaCl, but if I can precipitate out NaClO3 then it doesn't seem like a big issue after all. After all I don't have to remove all of it, the liquor can be recycled.

DeltaH: I haven't figured out why yet (or even if), but from what I've read MMO and perchlorate isn't a good combo. But there seems to be a great deal of confusion on the subject, some sources say that platinum works for perchlorate but is sensitive to chlorides, others say it's a good choice for chlorate as well. I need to be sure before I make a decision, I don't want a long-winded research project trying to figure out why expensive anodes go *pooof*.

morganbw - 7-12-2014 at 13:43

Quote: Originally posted by jock88

Dann2's page is now here

http://oxidizing.typhoonguitars.com/

Some of the stuff of the http://www.utahpyro.org/compositions/ site (pasted below) is nonsence.

*start of quote*
...................
.....................

Electrode materials for perchlorate manufacture.

DSA: DSA stands for Dimensionally Stable Anode. This is the common term used to
refer to anodes consisting of a layer of noble metal oxides (usually RuO2 and TiO2)
coated onto a substrate, usually titanium. This type of anode is finding increased use in
industrial cells because of its comparatively low cost when compared to platinum and its
resistance to corrosion. The chemicals required to manufacture these anodes are
expensive and difficult to handle. However, if the chemicals can be obtained and suitable
equipment is available, the procedure to make the anode seems fairly straightforward and
may be an option. For the preparation of these, the reader is referenced to the literature.
Again, I'd be most interested in anyone’s experiences with this type of anode.
Magnetite: This material has found use in industry in the past, but is rarely used
nowadays due to its relatively high corrosion rate and low efficiency for perchlorate
manufacture. The anodes are made by melting and casting FeO.Fe2O3 into the required
anode shapes. I have little literature available on this material, so it is not further
discussed here. *end of quote*

I can see that it may not do well for perchlorate but for chlorate???? why is it nonsense.

Hennig Brand - 7-12-2014 at 14:29

Most, or all, commonly available DSA/MMO anodes are not suitable at all for making perchlorates. However, it seems that it is possible to make DSA that are. I found a reference to the following patent on Dann2's site.

Attachment: US4267025 Electrodes for Electrolytic Processes, Especially Perchlorate Production.pdf (363kB)
This file has been downloaded 796 times

It is also possible, given the description in the text, that the Utah pyro people put the wrong heading on that section. It isn't that hard to mix up chlorate and perchlorate. It sounds like they were talking about producing an experimental Dimensionally Stable Anode, however, especially since he says or implies at the end that he has never tried it and would be interested to hear of any ones experiences if they make one. Since the common MMO anodes are so cheap and readily available it makes a lot of sense that if one is going through the trouble to make one that it would be so it could do things the readily available varieties couldn't (make perchlorates).

[Edited on 7-12-2014 by Hennig Brand]

Fulmen - 7-12-2014 at 15:21

That was my impression as well, none of the readily available MMO's were suited for perchlorate. And this is an absolute requirement for me, readily available, long lasting anodes. I did read something about platinum not being the best option or a chlorate cell, but I can't remember where i found that.

Hennig Brand - 7-12-2014 at 16:27

I think with Dann2's site and the other links you will find everything you need, if you take your time and read through it. Personally I would probably use graphite anodes to make sodium chlorate; removing crops of sodium chlorate and recharging the electrolyte with more sodium chloride and water at the appropriate times. There are ways to filter out the really fine carbon dust from carbon anode erosion; filtering through a layer of diatomaceous earth is one way. Once I had sodium chlorate of high purity (sodium chloride in low concentration is bad for platinum anodes), I would produce sodium perchlorate using a platinum anode of some sort (what I have now is a platinum coated titanium anode).

jock88 - 7-12-2014 at 17:07

From this link

http://oxidizing.typhoonguitars.com/chlorate/leaddiox/platin...

To quote:
In effect, platinum forms an equilibrium or quasi equilibrium state when evolving chlorine, and a rather different state for oxygen evolution. During co-joint oxygen and chlorine evolution, which occurs in dilute brine, there is interference in the formation of surface layers and this leads to accentuated metal dissolution.(Platinum Metals Rev., 1998, 42, (l), 27-33, available below)

The above will occur when a chlorate cell is getting very low in chloride (it will be very high in Chlorate) and perhaps on the verge or just starting to make perchlorate.
Those titanium + a platinum coating a few microns thick will be eaten away pronto and you are down the price of the anode.
The crucible seems a great idea.

deltaH - 7-12-2014 at 22:07

@Fulmen,

Have you tried calling up a technical advisor in a MMO electrode producing company?

Fulmen - 8-12-2014 at 00:32

Jock: Thank you for that link, that was the information I was looking for. It seems Pt can be used for ClO3 as well, as long as the Cl-concentration isn't too low. And there really isn't any reason for running a cell to pure ClO3, but considering the cost of a MMO-anode it seems safer to run two separate setups.
The wear rate of 2-7g Pt/ton ClO4 doesn't seem that bad, but most platinized anodes are only 2,5 microns thick. Not sure how much ClO4 I can expect before the coating gives, but it seems like the best route all in all. Solid Pt is just too darn expensive considering the surface area available and the recommended current densities.

Hennig Brand - 8-12-2014 at 09:37

You shouldn't be completely resistant to doing some research on your own. Dann2's site is laid out very well for easy digestion. You will learn many things you didn't realize you didn't know, when searching for the things you knew you didn't know. The quality of learning in general will be better. BTW, I am still an amateur at this as well.

I dug through some old boxes and found a couple of old improvised cells, with commercial anodes, that were used on a window ledge to produce chlorate and perchlorate. The vessels were food storage containers, with sealable lids, from the local dollar store. The large one, which was used to produce chlorate, has a MMO anode and SS cathodes. The small one, which was used to produce perchlorate, has a platinized titanium anode and a titanium cathode. I found some of the potassium chlorate and perchlorate that was last produced with these cells too in the same boxes. The cells were last run about six years ago.

Cell with platinum anode on right and cell with MMO anode on left.jpg - 252kB

Cell with platinum anode on right and cell with MMO anode on left internals.jpg - 259kB

[Edited on 8-12-2014 by Hennig Brand]

Fulmen - 8-12-2014 at 23:32

I'm not worried about that part, just getting the cell to run properly and refining the product should provide more than enough research to keep me busy for a while. The more I read up on the subject the more sense PbO2 seems to make, sadly I'm not set up to do that kind of work. Nor am I interested in a long-winded project just to get working anodes. MMO and Pt seems like my best options for now, I do have graphite for a chlorate test-run but not enough to use it for a permanent setup. Besides, filtering can be much more problematic than people think, so I don't mind skipping that part if I can.

I'm still reading up on the purification part and pondering how to organize the production sensibly. For a few runs you can always wing it, but for a more permanent setup I really need a good, predictable procedure and some way of determining quality. That is the real challenge here I think, the cell itself isn't that complex project.

Fulmen - 10-12-2014 at 09:48

Well, this seems quite doable. A 3x6" MMO-anode should be more than enough, if I assume the surface area is roughly equal to it's overall dimensions and a current density of 250mA/cm^2 it should be able to handle more than 50A and capable of producing roughly 500g per day! Now THAT is a cell I'd like to build

A more realistic setup is 4A, 250ml volume and roughly 250g/week. The real challenge seems to lie in the purification. The thought of ammonium chlorate in the final product has a pretty high pucker-factor, so I'll have to find a reliable analysis. Luckily several exist, are there any more to consider than those listed here?
http://www.oocities.org/capecanaveral/campus/5361/chlorate/t...
And if anyone has experience with these I'd like to hear of them. The Indigo Carmine-test seems promising, so does the ammonium thiocyanate rapid test.

[Edited on 10-12-14 by Fulmen]

Hennig Brand - 10-12-2014 at 11:15

I have Indigo Carmine, but I didn't get it until after I made the last batch of potassium perchlorate. I just boiled the crude sodium perchlorate dissolved in water with a fairly large excess of sodium metabisulfite and hydrochloric acid for much longer than a normal treatment. A test to be sure all chlorate is destroyed is a good idea though, especially if it will be used to produce ammonium perchlorate.

Fulmen - 12-12-2014 at 03:29

Huh, I just found Methylene Blue B in my chem collection, not sure if I'll ever need it but it's nice to know I have it. As for the chlorate, Indigo Carmine seems to be the most sensitive test (ppm-levels) and not too complicated to perform.

As for the cell, Yates has a good point about it being more sensible to keep the chloride levels high than to mess with pH-adjustments. This presents an elegant option for chlorate extraction. By insulating/heating the cell so that cooling is required, the cooler should precipitate chlorate. The cell is kept saturated by adding solid NaCl.
Another option that should be more energy efficient is to use a heat exchanger to minimize heat losses, but I'm afraid that this would clog out due to precipitation.

Fulmen - 30-12-2014 at 13:18

Funny how one thing leads to another, I've been slightly side-tracked by the need for a rugged CC/CV PSU. It's basically a 12V/10A PSU and a couple of buck / boost regulators I've bought from DX for other projects. Still waiting for potentiometers to replace the on-board ones for panel mounts, so I finished a jam-jar prototype cell during the holidays using graphite / copper electrodes. Seems to work fine, but getting the darn thing air tight isn't easy. Outside is exposed to wind and snow, so I need to take precautions before I can run it outside. Thought I could pull off a trial run inside, didn't take me many minutes to realize that's not an option.
Seems to work fine though judging by the amount of chlorine gas that leaked out *cough*

Don't worry, I'm going to play nice with that stuff. Those that have been even mildly poisoned by chlorine gas will know how bad it really is, caught a lung-full at a plant I worked at and damn what a shitty day that turned out to be.

Hennig Brand - 30-12-2014 at 18:01

I had mine vented to the outside, through a piece of plastic tubing, which worked fine, but running a cell outside is obviously the safest if it is feasible. A long drill bit, like the ones cable and satellite dish installers use when drilling holes to run wires, was used to drill a hole through the wall just beside the window frame, or through the window frame itself, to run the tubing through to the outdoors. Yeah, chlorine gas is not healthy at all. IIRC, once the chlorate cell has been running a while, and the pH rises, the amount of chlorine production tapers off, unless of course acid is being added to keep the pH down.

Fulmen - 31-12-2014 at 04:53

After some work sealing up the lid it now runs fine indoors. The gas is bubbled through NaOH, can't smell any chlorine leaving. As you say, after a short while the pH drops enough to limit the amount of Cl2 that comes off.

But it's clear that graphite isn't my cup of tea, in fact the cell looks like a cup of strong coffee. So I do think I will need to order some anodes for this.

Hennig Brand - 31-12-2014 at 11:46

The following was taken from Dann2's site, from the page called "Reaction equations".

"At a low pH the cell will generate Chlorine gas which will escape out of the cell and this will cause the pH to increase. As the pH rises the ease with which Chlorine can escape out of the cell gets less and less and the cell will stabilize at a pH of about 9 or 10. At this high pH, practically all Chlorate is made by electricity by the Anodic Oxidation of the Hypochlorous ion (also known as Anodic Chlorate formation, or 'making Chlorate by electricity', or electrochemical Chlorate formation) at a maximum possible current efficiency of 66.66%, the nine electron route."

When I used the copper coated carbon rods I would carefully remove/peel the copper off of the rod except for a bit at one end to allow a better electrical connection with the supply wire. I tried several different glues and things to seal the electrodes in the top of the cells and I remember some lasted better than others, but I would have to go back and check and refresh my memory on which ones were better. I believe I used hot melt glue a lot of the time, which wasn't permanent but stood up reasonably well. It goes without saying that a vessel with a lid that seals well is required. The containers in the picture I posted a couple of posts up were a cheap dollar store variety, but they have a very good soft silicon seal for the cover.

[Edited on 31-12-2014 by Hennig Brand]

Fulmen - 31-12-2014 at 13:36

I'm using a plain jam jar with a metal screw-on lid, the connections are sealed with a screw and rubber gasket. Seems to be fairly tight, how the lid fares over time remains to be seen. I will need a better container somewhere along the way but it works for testing purposes.

It's currently running at 4A @ 3,2V, efficiency is anybodys guess but I'm satisfied with 50%. As for pH control I do have a pH-meter but I'm not sure how well it will handle this environment. It's too much hassle anyway, so unless someone finds a simpler method for measuring this I''m going to leave the pH as it is.

Hennig Brand - 31-12-2014 at 17:28

I never bothered with pH control so far. Controlling pH makes things more complicated.

Fulmen - 1-1-2015 at 02:37

From what I've read chlorate cells seems to be rat poison for pH-probes. I won't risk mine on it, so until a better method is devised I'll simply have to live without it.
I've thought about voltammetry of some sort, perhaps a pH-dependent passivation reaction that would give a useful value. But I suspect that brighter heads have thought long and hard about this, and nobody seems to have a good solution.

jock88 - 1-1-2015 at 19:23

It is better to think in terms of 'adding acid' as opposed to 'pH control'.
You simply add acid at a predetermined rate (so many ml per amp per hour) and that's that.
No need for pH probes or monitoring of pH.

Metacelsus - 1-1-2015 at 19:29

Yes, monitoring of current should be enough.

Fulmen - 1-1-2015 at 20:37

I've seen that method, but it doesn't really appeal to me. Without any measurements I cannot determine the optimum addition rate properly, and I really don't like working in the blind like that. Not sure what the consequences are if you add too much acid or how much the pH must be lowered before there's any real benefit. Getting a reliable dosing system isn't straightforward either, so for now I can't see the benefits outweigh the extra work&cost. But I will keep it in mind as this project progresses.

So far things seems to run quite well, the erosion of the graphite has dropped to a manageable level and the cell runs like it should. Haven't gotten any chlorate out yet, but that should be just a matter of time. My planned system is to switch between two charges, this allows me to filter and freeze out one charge while the other is running. Once I've accumulated enough chlorate too freeze out I should be able to calculate the yield in one or two day intervals.

Update: We have product! Not much, perhaps an ounce, but it's beautiful.
As for adjusting pH we don't really need an exact value, just something that tells us if it is way off in one direction or the other. Anything that tells when to add or stop adding acid should provide some control.

[Edited on 2-1-15 by Fulmen]

jock88 - 2-1-2015 at 15:09

Quote: Originally posted by Fulmen

Update: We have product! Not much, perhaps an ounce, but it's beautiful.
As for adjusting pH we don't really need an exact value, just something that tells us if it is way off in one direction or the other. Anything that tells when to add or stop adding acid should provide some control.

[Edited on 2-1-15 by Fulmen]

Simply adding acid gives you a stable pH once the cell has started up and run for a while (one day).
This has been done time and time again.
Adding acid simply needs a timer attached to a solenoid controlling a valve or a simple dripper (if you have a big cell).
Adding acid a few (at least four IMO) times a day will also
do the job. A second hand medical infusion pump is ideal and can be had for 20 dollars in ebay if you keep an eye out.

Rate of acid needed is approx. 0.146ml 12% HCl per amp per hour.

Read here:
http://oxidizing.typhoonguitars.com/chlorate/reaction.html
CONTROL OF PH IN CHLORATE CELLS

Graphite erosion is not so much of a problem when acid is added (pH 'controlled' if you like). About 20 to 50 grams graphite is eroded per kg Chlorate produced.

http://oxidizing.typhoonguitars.com/chlorate/reaction.html

pH probes are only needed if you want to experiment and keep on eye on things (nothing wrong with that). If simply making chlorate there is no need for expensive pH probes. You will need an expensive one, the cheap ones are useless.

long discussion on K chlorate here
http://www.amateurpyro.com/forums/topic/1629-making-potassiu...

[Edited on 2-1-2015 by jock88]

Fulmen - 2-1-2015 at 17:17

YOU'RE NOT HELPING! I'm trying to keep this project simple, with all your help it's going to grow completely out of control

But you're right, it shouldn't be as hard as I initially assumed. Since chlorine losses increase as the pH goes down the process is going to be fairly self regulating. Any reduction in pH should be beneficial, so this might be worth it after all. Thanks for the help.

Fulmen - 3-1-2015 at 13:57

Now you've done it! I've already started designing a new cell, I'm thinking 6mm clear SAN plastic (glues easily and allows me to see what happens), appr 700ml volume sized for a 3x6" MMO-anode. I also need to build a peristaltic pump for dosing small volumes. The pump body shouldn't be too hard to build, as for the driver I'm considering either a monostable vibrator and a self-parking design (think windshield wipers) or a stepper driven unit. I'm leaning towards the stepper as both the motors and drivers are cheap and versatile...

hyfalcon - 3-1-2015 at 16:55

You're going to have severe heating problems if you drive a 3x6 at it's maximum current density. You need at least a 4000ml vessel for that size anode.

Fulmen - 3-1-2015 at 17:24

Not going to go anywhere near the limits, as of now I only have a 4A PSU and I'm thinking 8-12A max with suitable cooling. The basic idea is to use a temp-controlled pump to circulate the liquid through a cooling tank to precipitate the product.

One thing I'm having trouble finding is discussions regarding convection in the cell. With proper pH regulation time is needed to increase yield, in theory convection could provide some additional reaction time before any chlorine escapes the cell. Has anyone tried this?

hyfalcon - 3-1-2015 at 18:55

I've had temperature stratification before and had to run an air pump to mix the layers of temperature variation.

Of course that was a 5 gallon plastic bucket.

[Edited on 4-1-2015 by hyfalcon]

jpsmith123 - 3-1-2015 at 20:14

If you get a MMO anode and you want to try an experiment, here's something that I don't think has been tried yet:

Paint the MMO with a bismuth nitrate & alcohol solution and then heat treat it to decompose the nitrate to oxide. Maybe some of it will form a pyrochlore with the RuO2 in the MMO coating, and if so you may then have a perchlorate-capable anode. (Right now there are a few sellers on ebay selling Bismuth Nitrate).

Edit: I'm not sure if bismuth nitrate is soluble in alcohol, but apparently it's soluble in acetone and also glycerin.

Quote: Originally posted by Fulmen

Now you've done it! I've already started designing a new cell, I'm thinking 6mm clear SAN plastic (glues easily and allows me to see what happens), appr 700ml volume sized for a 3x6" MMO-anode. I also need to build a peristaltic pump for dosing small volumes. The pump body shouldn't be too hard to build, as for the driver I'm considering either a monostable vibrator and a self-parking design (think windshield wipers) or a stepper driven unit. I'm leaning towards the stepper as both the motors and drivers are cheap and versatile...

[Edited on 4-1-2015 by jpsmith123]

Fulmen - 4-1-2015 at 08:28

Nah, not going that route anywhere soon. Electrochemistry isn't my strongest subject, and I try not to indulge in experiments when I'm not competent to work out the theory. It usually ends up as a waste of time without providing any real new insight. Just building a proper cell with all the bells and whistles should keep me busy for a long while. Once I'm ready to make perc I'm going to buy a Pt-plated anode, if I ever wear that one out we'll see about such experiments.

hissingnoise - 4-1-2015 at 08:49

This might be of some interest . . .

markx - 4-1-2015 at 09:54

Quote: Originally posted by Fulmen

I also need to build a peristaltic pump for dosing small volumes. The pump body shouldn't be too hard to build, as for the driver I'm considering either a monostable vibrator and a self-parking design (think windshield wipers) or a stepper driven unit. I'm leaning towards the stepper as both the motors and drivers are cheap and versatile...

There is really no need to build a dosing pump from scratch:

http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_n...

http://www.ebay.com/sch/i.html?_odkw=6v+Multifunction+Self-l...

http://www.ebay.com/sch/i.html?_from=R40%7CR40%7CR40%7CR40&a...

Just order one and couple it with a PWM and a timer unit....tunable volumes and preprogrammed timing for the pH control . It probably can't be done any easier.

http://www.sciencemadness.org/talk/viewthread.php?tid=26826&...

Fulmen - 4-1-2015 at 12:16

I saw those, but they seemed flimsy. Besides, I have too much in order as it is and all the tools and materials to build one from scratch. I've started a thread about it here:
http://www.sciencemadness.org/talk/viewthread.php?tid=59870

markx - 5-1-2015 at 00:55

Yes, of course you can build a much sturdier pump if you have all the materials and tools at hand. My suggestions were based on the assumption that building the pump might be a limiting factor to the progress of the main goal of this experiment...the creation of an effective pH controlled cell.

Fulmen - 5-1-2015 at 03:48

Ah, but you're missing the main goal. To build stuff and have fun

markx - 5-1-2015 at 05:18

Nah....that is pretty much my moto too, but lately I've begun to make some compromises and no longer build ALL of the stuff. The fun has not been compromised by that so far

Fulmen - 5-1-2015 at 07:24

I don't disagree, but right now money is pretty tight. besides, these pumps has a rather high delivery rate which I don't want. Using a stepper solves that, but that means modifications that might not be so easy with a commercial unit.

Fulmen - 7-1-2015 at 23:17

Question: What is it that kills pH-probes? If it's the hypochlorite I guess it could be boiled off without affecting pH too much, adjusting the acid addition by measuring pH would be much simpler than having to measure cell efficiency. But I'm not killing my probe on this, so I'd like to know for sure if it can be done.

hyfalcon - 8-1-2015 at 03:20

I use an IV drip bag with dilute HCl in it. Works for me. Just adjust you concentration of acid to control the pH at whatever level you choose.

Get creative when you get the numbers ironed out and use it to dissolve your extra NaCl in it also. Kill two birds with one stone so to speak.

[Edited on 8-1-2015 by hyfalcon]

Fulmen - 9-1-2015 at 12:36

Leak testing:

Turned out pretty nice. Still need a lid, but that will probably have to wait to next week.

ecos - 19-1-2015 at 02:11

Hi All,

I just want to share this large cell for chlorate synthesis : http://youtu.be/PwewwZ9-2ok
the graphite rod was corroded ! : http://youtu.be/DH9yICU9p0Q

[Edited on 19-1-2015 by ecos]

[Edited on 19-1-2015 by ecos]

Chlorate/Perchlorate cells

ecos - 31-8-2015 at 02:09

Hi All,

I noticed in some videos on youtube that the electrolysis cell turns yellow as attached pictures.

is this due to the corrosion of anodes?

greenlight - 31-8-2015 at 05:03

I think the yellow colour is quite normal for the cell solution, it could be the chlorine content or maybe electrode corrosion but I am unsure.
I have run a chlorate cell a few times now and have noticed a slight yellow colour to the cell solution which goes away when the cell is cooled down.

In the process of setting up a perchlorate cell now and have everything except the electrodes as the Platinum ones are very expensive.
Has anyone had an success making sodium perchlorate with the cheaper Platinum coated Titanium electrodes as the anode?
Can you get at least one or two batches out of them before they corrode the whole Pt layer off?

hyfalcon - 31-8-2015 at 07:42

As long as you start with pure chlorate and don't go above 5-6V DC, you can get several runs out of them. Let the chlorate levels get low or overdirve the voltage and it will peal the platinum right off the titanium.

greenlight - 31-8-2015 at 08:18

I was going to start with Sodium chloride and run all the way to perchlorate

Power supply is 5 volt 40 amp.
Hopefully I can still get one or two out of a Pt anode.

ecos - 31-8-2015 at 11:14

I found some MMO anodes that can support till 300-250 mA/cm2
The size of the annodes where 2"x6"..... they can support max 21-18A

Talking about 40A is madness for small anodes.
Safe side to be around 10A.

I am not expert but i started learning about chlorate/perchlorates

greenlight - 31-8-2015 at 19:08

Alan yates has pictures on his site of a very small perchlorate cell and the power supply is over 50 amps. Registers 56 amp on his meter in the pic.
He says the major problem is boiling of the electrolyte solution and of course abuse of the electrodes but very fast conversion.

I was going to use a 6.5 volt power supply but was unable to find one online so I see how the 5 V 40 amp turns out.
I want to do a 1-1.5 L cell in which you can place the electrodes apart more to control the heat or a water bath.
Still undecided on the anode.

nux vomica - 31-8-2015 at 22:30

This is my cell I used years ago its made from pvc plumbing fittings and has a capacity of 800mls the mmo anode is 5×7.5 cms and I ran it at 20 amps or 266ma per cm2.
Perchlorate is not so bad on your anode I found just dont try barium chlorate that's what damaged my cells anode
Nuxy

ecos - 31-8-2015 at 23:56

I read a lot about the anodes, for MMO :

Quote:

MMO (Mixed Metal Oxide (Trade Name: DSA (Dimensionally Stable Anode)), usually made from the Oxides of Noble Metals, Ru and Ir, on a Titanium (a Valve metal) substrate. Used by ALL Chlorate Industrial setup's nowadays. Not recommended to be used in electrolytes where the Chloride level has been let drop very low (30g/l absolute minimum), better to keep at or above 50g/l Chloride. They can be used at relatively high current densities, 300mA per square cm, around 200mA per square cm could be considered a working value. There are a range of MMO types on the market. In corrosion prevention applications they are used in very low Chloride concentrations at low current density. They are also used in swimming pool Chlorination systems.
MMO will not make Perchlorate AFAIK though some types (Pt Oxide based) may be capable of making Perchlorate.
MMO should not be operated at high temperatures. Pool Chlorination Anodes are mostly MMO Anodes though sometimes they are Pt metal based. Do not use Fluoride additive with MMO

I don't understand why MMO won't make perchlorate?!

nux vomica - 1-9-2015 at 00:30

Quote: Originally posted by ecos

I read a lot about the anodes, for MMO :

Quote:

I don't understand why MMO won't make perchlorate?!

You can its just harder on the anode than making chlorates I calculated when most of the sodium chlorate had been converted into sodium perchlorate then destroyed the leftover chlorate then added potassium chloride to form the potassium perchlorate nux.

greenlight - 1-9-2015 at 01:17

@ Nux, I always thought you needed a Pt anode to make perchlorate.
How did you calculate when it was finished, using methylene blue?
Did you do a test on the final product to make sure it was Potassium perchlorate?

nux vomica - 1-9-2015 at 01:55

Quote: Originally posted by greenlight

@ Nux, I always thought you needed a Pt anode to make perchlorate.
How did you calculate when it was finished, using methylene blue?
Did you do a test on the final product to make sure it was Potassium perchlorate?

It was over 10 years ago but yes I used the methyline blue test and I think the amps had dropped a lot so it wasn't worth running the cell anymore , I used the matchbox test to see if there was chlorate left , put a small amount on the box striker and rub it across it like striking a match, perchlorate wont react, just dont burned your finger though:D
Its not as efficient as platinum but you can stil get perchlorate from a mmo anode.

Edit tried a little perchlorate solution with methyline blue purple precipitate straight away filter paper is wet so color not as good as dry paper .

[Edited on 1-9-2015 by nux vomica]

greenlight - 1-9-2015 at 02:41

That's a good idea for a quick test using a matchbox as well as using the methylene blue.
I think I will still use the platinum coated anode with titanium cathode and see how long they actually last.

How big was the cell you used and how long did it take to go all the way to perchlorate?
Also how many volts was the cell?

Cheers

[Edited on 1-9-2015 by greenlight]

nux vomica - 1-9-2015 at 03:20

Quote: Originally posted by greenlight

That's a good idea for a quick test using a matchbox as well as using the methylene blue.
I think I will still use the platinum coated anode with titanium cathode and see how long they actually last.

How big was the cell you used and how long did it take to go all the way to perchlorate?
Also how many volts was the cell?

Cheers

5 volt and 800mls cannot remember exactly but I think it was over 5 days run time , I bought a piece of mmo 300×300 so I wasnt worried about damaging the anode but yes platinum would be better nux.

ecos - 1-9-2015 at 03:53

I would like to buy the anode for my tests.

i found this link for MMO anode(Iridium/Ruthenium Oxide ) and Titanium cathode : http://store.theamateurchemist.com/mmo-solid-plate-anode-tit...

they write in the description :

Quote:

These are great for a variety of uses: all kinds of electrolysis, chlorinators, chlorate and perchlorate cells, ionizers, precious metals plating, etc.. These are quality electrodes and will last for a long time if they aren't damaged (eg - send too much current through them). The max anode current density for mmo is around 250 - 300 mA/cm^2

do you think the plates are a good option or they would corrode easily ?

greenlight - 1-9-2015 at 04:13

Thanks Nux, and Ecos what are you trying to make with the electrodes you linked?
I have brought the same electrodes from the page you linked twice for a chlorate cell one time being for spares.
They work very well, I have done a few batches of Potassium chlorate with them and they show no signs of wear at all.
I'm going to try his platinum coated electrode in my perchlorate cell.
You can also get them with Titanium strips welded on as an extra option if needed, my latest ones are in the pic below.

[Edited on 1-9-2015 by greenlight]

ecos - 1-9-2015 at 04:19

Yes, I am planning to ask for Titanium strips to be welded.

I am planning for KClO4, do you think the would be efficient or should i stick to Pt ? they state in the Quote above they can be used for both chlorate and perchlorate cells.

greenlight - 1-9-2015 at 04:23

I think it would take a lot longer using MMO as the anode, and would probably end up wearing it out fast as well.
The best anode material is pure platinum or lead dioxide but they are both expensive.
If your only trying to make Potassium perchlorate personally i would go the platinum coated but it's up to you. Nux got KCl04 with MMO anode as stated above.
I am about to put the order through for a couple of his platinum coated electrodes now, only thing I'm worried about is excessive wear

greenlight - 1-9-2015 at 04:40

Hang on, the Platinum coated electrode from the Ecos linked only has a Pt coating 1 micrometer thick.
This one from ebay would probably be better if buying a Pt coated electrode as it is 2.5 micrometers thick:

http://www.ebay.com/itm/PLATINIZED-TITANIUM-ANODE-PLATING-AN...

ecos - 1-9-2015 at 06:21

thanks Greenlight for the info.

2.5 um is better than 1u and the price is just $6 difference !

I will buy it. but what should i do for the cathode, should i buy SS or titanium electrode?

greenlight - 1-9-2015 at 07:07

Yes, it seems like the better option.
As for the cathode, I am going to buy one of the single Titanium electrodes from the site you linked before as they are quite cheap but either option is okay to use as far as I know.

franklyn - 1-9-2015 at 08:34

Has the use of semiconducting materials such as doped silicon carbide been investigated for suitability in electrodes ?
Perovskite electrode cells have also been investigated , lightly discussed in this brief _
Anodes for Electrochemical Processes
www.isca.in/rjcs/Archives/vol3/i6/From%20Editorial%20Desk.pd...
I mentioned this once before and damn2 thought the resistance would be too high and therefore exhibit poor efficiency.
http://www.sciencemadness.org/talk/viewthread.php?tid=8592&a...
Related threads _
http://www.sciencemadness.org/talk/viewthread.php?tid=8592
http://www.sciencemadness.org/talk/viewthread.php?tid=9783

Operating a water electrolysis cell under pressure significantly improves performance. Has this been looked into regarding
Chlorate/Perchlorate production ?
A bubble curtain model applied in chlorate electrolysis
http://publications.lib.chalmers.se/records/fulltext/162957....

Another notion I recall mentioned in some patents is circulating the electrolyte in the cell with the intent of improving the performance.
Ultrasonically agitating the electrodes with a Piezoelectric transducer does not seem to have been considered anywhere.

.

ecos - 1-9-2015 at 23:41

I think we have a lot of factors affecting the efficiency of chlorate and perchlorate electrolysis :
1- electrode material -- platinum is the best
2- PH -- should be around 6.8
3- Temperature
4- ultraviolet rays affect the synthesis.
5- circulation of the electrolyte
6- current density
7- Pressure
..... etc !

wow

this amaze me a lot. I thought the process is very easy but now I realized how many details we need to care about to have efficient cell

ecos - 1-9-2015 at 23:55

Quote: Originally posted by nux vomica

Quote: Originally posted by ecos

I read a lot about the anodes, for MMO :

Quote:

I don't understand why MMO won't make perchlorate?!

You can its just harder on the anode than making chlorates I calculated when most of the sodium chlorate had been converted into sodium perchlorate then destroyed the leftover chlorate then added potassium chloride to form the potassium perchlorate nux.

would you please explain what you mean by "Harder"? the factor here is time,current ,....?

nux vomica - 2-9-2015 at 00:54

Quote: Originally posted by ecos

Quote: Originally posted by nux vomica

Quote: Originally posted by ecos

I read a lot about the anodes, for MMO :

Quote:

I don't understand why MMO won't make perchlorate?!

would you please explain what you mean by "Harder"? the factor here is time,current ,....?

Harder as in the wear to the anode will be faster compared to if you only made chlorate in the cell.

ecos - 2-9-2015 at 03:25

Thanks Nux,

Let me ask , chlorate and perchlorate are synthesised with the same setup but different run-time duration.

so we can find perchlorate while making chlorate only ! how this is controlled to avoid wear of anode?

nux vomica - 2-9-2015 at 04:33

Quote: Originally posted by ecos

Thanks Nux,

Let me ask , chlorate and perchlorate are synthesised with the same setup but different run-time duration.

so we can find perchlorate while making chlorate only ! how this is controlled to avoid wear of anode?

You can use potassium chloride as your cell electrolyte, and run it until you see a reasonable amount of chlorate crystals form, then let the cell cool so the rest of the chlorate separates, filter the chlorate then add a calculated amount of potassium chloride to refresh the cell and start the run again.

Also you need to keep the cell temperature controlled so it doesn't get to hot and make sure the anode is fully submerged in the cell liquid to stop corrosion of the anode.

[Edited on 2-9-2015 by nux vomica]

ecos - 2-9-2015 at 05:22

regarding the erode of the anode :

Quote:

Anode current densities used vary widely. They range from 100mA/square cm to 700mA/square cm. Use about 300mA/square cm. Pt will increasingly erode if used in a Chlorate cell with a low concentration of Chloride. Keep above 80 grams per litre Chloride. Pt will also increasingly erode if used in a Perchlorate cell if the concentration of Chlorate is low, though the extra erosion appears to be little.

I found this part on Link

this means when the cell starts running the chloride level will decrease because chlorate is formed and participated in the bottom of the cell.

keep the cell running for long time would cause the anode to erode more quickly ! , this also means we need to stop the cell before most of the chloride is transformed , threshold should be 80 grams per litre Chloride.

if i am correct in my understanding , how could we calculate the run-time of the cell ?!

greenlight - 2-9-2015 at 05:45

Yes, like Nux said, just stop before the chloride content gets too low, filter and refill the cell with sat. Nacl solution and start again. Its easier than perc would be because you can see the Potassium chlorate precipitating on the bottom. In the perc cell I think you have to rely on the methylene blue and boiling the residual chlorate.

My chlorate cell is 900ml volume. I let it run for about 100 hours and chilled it in the fridge before filtering. By this time, there was a thick layer in the bottom. Yield was 365g the first time and 300g the second.

[Edited on 2-9-2015 by greenlight]

ecos - 3-9-2015 at 00:03

Thanks a lot Nux and Greenlight.

is there any indication to know if the chloride concentration is going down ?

I was thinking about tracking the current consumed by the cell, I think if the chlorate decrease the current intensity will vary and this can be a good indication to stop the cell rather than waiting for fixed amount of time !

I am planning to buy a shunt resistor and insert it in serious with the electrode. I will be able to read the voltage drop on the resistance to know the current passing in the cell.

do you think the idea will work ?

100amp-current-shunt-resistor[1].jpg - 12kB

100amp-current-shunt-resistor[1].jpg - 12kB

[Edited on 3-9-2015 by ecos]

nux vomica - 3-9-2015 at 01:52

You could use one of these.

http://m.ebay.com/itm/Digital-60V-100A-Battery-Power-Analyzer-Watt-Meter-Balancer-For-DC-RC-Helicopter-/190863796444?nav=SEARCH

ecos - 3-9-2015 at 03:16

Quote: Originally posted by nux vomica

You could use one of these.

http://m.ebay.com/itm/Digital-60V-100A-Battery-Power-Analyzer-Watt-Meter-Balancer-For-DC-RC-Helicopter-/190863796444?nav=SEARCH

good tool

so what would be the current value to stop the cell ?

macckone - 3-9-2015 at 06:46

Quote: Originally posted by ecos

Quote: Originally posted by nux vomica

You could use one of these.

http://m.ebay.com/itm/Digital-60V-100A-Battery-Power-Analyzer-Watt-Meter-Balancer-For-DC-RC-Helicopter-/190863796444?nav=SEARCH

good tool

so what would be the current value to stop the cell ?

You wouldn't use current. You would use amp.hr.
Very cool meter.

ecos - 11-9-2015 at 00:46

it is very interesting to see 1mm coated PbO2 anode : Link

any reason for this high cost ?

[Edited on 11-9-2015 by ecos]

[Edited on 11-9-2015 by ecos]

greenlight - 11-9-2015 at 05:45

I have seen those too, they would be good in a perc cell and it would take a while to kill them.
I was wondering the same thing, bit expensive.

ecos - 11-9-2015 at 11:57

I think it can be done easily :
https://youtu.be/bZMWEYiTtso

ecos - 15-9-2015 at 04:46

one of the factors that affect the performance is circulation of the electrolyte. i found that mentioned in this thread.

is it possible to use air bubbler instead of magnetic stirrer ?

ecos - 19-9-2015 at 12:15

Finally I received my MMO plates. I am waiting for The platinum mesh anode and the lead dioxide anodes

I should connect the dark one to the +ve voltage and the other one to the negative, the question there: what should be the distance between the two plates?

[Edited on 19-9-2015 by ecos]

hyfalcon - 19-9-2015 at 17:11

Aquarium pump with a piece of tubing run to the bottom of the reaction vessel is all you need. Just needs some turbulence to keep fresh electrolyte moving around the electrodes. This also keeps temperature gradients from being a factor.

As far as distance of the electrodes. This depends on how big your power supply is. How hard are you planning to push them?

[Edited on 20-9-2015 by hyfalcon]

greenlight - 19-9-2015 at 20:55

@Ecos, where did you order your Platinum mesh and Lead dioxide anode from?
I am still looking for the right one.

ecos - 20-9-2015 at 02:32

Quote: Originally posted by greenlight

@Ecos, where did you order your Platinum mesh and Lead dioxide anode from?
I am still looking for the right one.

I got the Platinum anode from the link you provided me before : Link

for the Lead dioxide anode : Link

fortunately i took the last piece

ecos - 20-9-2015 at 02:39

Quote: Originally posted by hyfalcon

Aquarium pump with a piece of tubing run to the bottom of the reaction vessel is all you need. Just needs some turbulence to keep fresh electrolyte moving around the electrodes. This also keeps temperature gradients from being a factor.

As far as distance of the electrodes. This depends on how big your power supply is. How hard are you planning to push them?

[Edited on 20-9-2015 by hyfalcon]

I am planning to do that using magnetic stirrer since it will make sure all parts of the electrolyte is moving , do you think it would better than air pump ?

I bought a new PC power supply (350 Watt), it can deliver 10A for 5V. I think this would be good for chlorate cell.

putting the electrodes far away from each other will increase the resistance between the electrode and decrease the current flow. is that desired?

hyfalcon - 20-9-2015 at 03:40

No, closer is better. Further apart and you will overheat the electrolyte. Too close and those flat electrodes could warp and short. I usually used the distance between electrodes to control the temperature.

ecos - 20-9-2015 at 05:42

is there anyway to know the distance so i can have around 8 A current?

would 1" distance be fine ?

ecos - 2-10-2015 at 15:09

I built my chlorate cell and it is operating now.
I started to see the orange colour coming on the surface and near the gas exit.
I started to feel this is not due to corrosion because the electrodes are new and the cell operated for few hours only. I also included pictures for that(the dark surface is epoxy)

any idea why I have this strange orange surface ?

My cell operates at 3A under 5v. I am not satisfied with this current so I tried to get the electrodes as close as much as I can but now it is 4A and the electrodes became hot.

I am thinking to add another SS cathode to increase the current or I can increase the voltage to be 12V. I am not sure which option would be better !

[Edited on 3-10-2015 by ecos]

[Edited on 3-10-2015 by ecos]

hyfalcon - 3-10-2015 at 02:25

2 smaller cathodes is better than one large one. Better charge distribution.

What are you elctrolysing? NaCl or KCl? If KCl then mag stirring is out. I've had chlorate crystals even try to clog the air tube before. Make sure you've got your air on full force. In larger reaction vessels, crystal mass falling out of solution can cause problems, especially if you try to pump or move your electrolyte out of the temperatures in the main vessel. Tubes freeze solid with chlorate crystals. Can be a mess to clean up.

[Edited on 3-10-2015 by hyfalcon]

ecos - 3-10-2015 at 06:02

Quote: Originally posted by hyfalcon

2 smaller cathodes is better than one large one. Better charge distribution.

What are you elctrolysing? NaCl or KCl? If KCl then mag stirring is out. I've had chlorate crystals even try to clog the air tube before. Make sure you've got your air on full force. In larger reaction vessels, crystal mass falling out of solution can cause problems, especially if you try to pump or move your electrolyte out of the temperatures in the main vessel. Tubes freeze solid with chlorate crystals. Can be a mess to clean up.

[Edited on 3-10-2015 by hyfalcon]

I have KCl in the electrolyte. I don't use an air pump but I use magnetic stirrer instead.
The magnetic stirrer is 12v computer fan mounted on it a hard disk magnet. It works well.

is there any problems from using mag stirrer?

[Edited on 3-10-2015 by ecos]

hyfalcon - 3-10-2015 at 08:10

As your electrolysis continues chlorate will fall out and foul your stirrer.

ecos - 3-10-2015 at 08:26

Ahaa. Good point.
If this is the only reason then i can manage to solve this.
I will buy a small pump and try to connect it.

But would the ciculation of the electolyte disturb the gas formation on the electodes??

please support

ecos - 3-10-2015 at 10:43

One day passed and nothing participated in my cell.

this is the procedure I followed.
1- I added 600 gram of KCL to 2.5 liters of tap water (it was normal cold water, I didnt boil)
2- I used PC power supply , I used the 5 v terminal. it supply 3A.
The MMO rode is connected to the +ve terminal , The platinum is connected to the -ve terminal
3- after the electrolyte became warm , I kept adding KCL (another 250 gram were added)
4- I used magnetic stirrer to circulate the electrolyte.
5- I found the voltage of the PC supply dropped to 3.5 v and the current was 5A now.

I use cheap power supply this is maybe the reason the voltage is dropping in it with time.

I measure the PH and it is between 5 and 6. I don't know why it is like this

I can't see any kind of participation till now

and I feel disappointed

[Edited on 3-10-2015 by ecos]

[Edited on 3-10-2015 by ecos]

ecos - 4-10-2015 at 03:34

After one and half day. I stopped my cell and tried to see if anything would participate but nothing till now.

what concern me is the electrode state, the cathode (platinum) looks darker and has dark region on it ! any reason for that ?

Deathunter88 - 4-10-2015 at 05:26

Quote: Originally posted by ecos

I think we have a lot of factors affecting the efficiency of chlorate and perchlorate electrolysis :
1- electrode material -- platinum is the best
2- PH -- should be around 6.8
3- Temperature
4- ultraviolet rays affect the synthesis.
5- circulation of the electrolyte
6- current density
7- Pressure
..... etc !

wow

this amaze me a lot. I thought the process is very easy but now I realized how many details we need to care about to have efficient cell

The process is easy, if you don't mind sacrificing some efficiency. By the looks of it, you haven't done any of this before, so I suggest you just order the electrodes and go for it. Then learn from your mistakes. Once you start you realise that a lot of the things on your list is out of your control and so you have to accept it. Even is difference in efficiency of 50% is not a big deal, seeing as we are amateur chemists. Instead of say running it for 2 days you run it for 4 days, no biggie.

Here is a handy calculator to calculate how long to run your cell.
http://www.vk2zay.net/calculators/?body=chlorates.php

One last thing, I feel that thermal decomposition of chlorate to perchlorate to be faster (although less efficient). I'll leave finding out how to do that as an exercise to not rely on others so much.

ecos - 4-10-2015 at 06:27

I already got the electrodes , please check previous posts and pictures.
I also used mag stirrer for electrolyte circulation.
I have HCl for PH control
The temperature was around 50 degrees.

I think i ask for solution of my problem not homework !

ecos - 7-10-2015 at 04:22

I noticed that no chlorine gas is coming out of the tube i mounted on the cover of the cell.
I put the terminal of the tube in water and i cant see any air pupples coming out!
Would the chlorine gass dissolve back in the cell??
When i open the cover of the cell i start to smell chlorine!
Any suggestions?

Pages: 1 2