Sciencemadness Discussion Board

NaClO4 production using a Pt clad Ti anode and a Ti cathode.

axehandle - 27-4-2004 at 16:30

I'm hesitant to start a new topic regarding chlorate production since there are so many already, but I'm doing so anyway. Moderators, move this if I'm in error.


I've recently built a chlorate/perchlorate cell with 5 liter capacity, where the anode is a platinum clad titanium mesh and the cathode is pure titanium.

The power is drawn from an old ATX PSU capable of 30A at +5V.

My goal is to start out with a saturated NaCl solution and end up with (mostly) sodium perchlorate.

I've just turned the cell on, and will report how it goes.



[Edited on 2004-4-28 by axehandle]

t_Pyro - 27-4-2004 at 21:42

I see you've already started using your new-found electrodes to the max! Approximately what is the electrode area of the anode, and what is you current density at the anode?

Your setup looks interesting, but the cell elements can't be made out too clearly. Would it be possible to post a closeup of the setup?

Saerynide - 28-4-2004 at 01:00

Playing with the new toys already I see ;)

Im guessing you drilled holes in the top of the jar for the electrodes right? Looks kinda like the wires come out the side in the pic.

Edit: Oooooh... the jar's all nicely filled with Cl2 :D

[Edited on 28-4-2004 by Saerynide]

Upgrades.

axehandle - 28-4-2004 at 03:29

Here's a better picture. To answer your questions, I have no idea what the current density at the anode is, but the cathode is a Ti strip approximately 150x8x1mm.

The electrode interdistance is approximately 20mm, which seems a lot more due to the optical properties of water in a glass cylinder...

After receiving some advice from chemoleo, I decided to heat the vessel. It's therefore now placed in a water bath on a thermostatically controlled hotplate. The soluability of Cl2 in water rises drastically with temperature as well, I've just read.

Yes, the electrodes and the gas vent pipe go through drilled holes in the jar lid. Those diamond coated hole saws are awesome!

If it seems necessary, I'll buy a current regulated power supply (i.e. a car battery charger) today. I think the voltage drop is quite severe.


t_Pyro - 28-4-2004 at 18:14

If you're having problems with the voltage drop, it may be possible that the salt solution isn't concentrated enough. In fact, when I'm done concentrating the salt solution, it has a slight milky white look to it (probably due to some fine suspended NaCl). The other possibility could be that your power supply just isn't delivering. I've seen that before- manufacturer claims it can provide 25A at 5V, but it peaks out at 11A!

About the necessity to heat: The cell effficiency increases at high temperatures, but you shouldn't have to heat it separately. Just leaving it to run on its own, the cell should reach upto 65<sup>o</sup> to 70<sup>o</sup>C, provided the current is high enough.

If you have a multimeter, you could monitor the current consumption of the cell. That should yield some answers.

[Edited on 29-4-2004 by t_Pyro]

When I realized

axehandle - 29-4-2004 at 18:35

that it would take weeks just to convert 1500g of NaCl into NaClO4, I put the project on hold, pending manufacturing/obtaining a set of HUGE PbO2 anodes, a large (50 liter) stainless steel vat used as a cathode, coolant pipes, a stirring system, and a 100% duty cycle welding transformer.

I gave up, the Pt anode is just too small. I want to produce at least 5kg of NaClO4 per week, and convert it to NH4ClO4.

Saerynide - 29-4-2004 at 23:16

Wow. What are you gonna do with all that? :o

darkflame89 - 30-4-2004 at 02:00

5 kg of sodium chlorate a week!!??:o

axehandle - 30-4-2004 at 03:35

Rocket motor experiments consume lots of fuel..... besides, half of it is for another guy.

hodges - 30-4-2004 at 13:01

Axehandle, how are you going to make sure that you don't have any chlorate (vs. perchlorate) in your product? Ammonium chlorate detonates spontaneously. I would be scared to make ammonium perchlorate unless I was real sure of the purity of my chlorate.

rikkitikkitavi - 30-4-2004 at 14:22

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

you probably know of this site axehandle.
Therer is listed some analytical methods of analysis of chlorate content (which you always will have) in the perchlorate-however I have looked after the chemicals in question used and they are not possible to get in SE. Not that I know of atleast.

fortunately it is easy to reduce chlorate f e x by SO2.
/rickard

axehandle - 30-4-2004 at 14:27

Thanks for the input. I have considered using magnetite as the anode, make huge amounts of NaClO3, then convert it to NaClO4 + NaCl using thermal decomposion (keep for several hours at slightly above the MP of NaClO3 (248C)). Then I planned to use FeSO4 or sodium bisulfate (used in wine making unless I'm mistaken) to destroy residual chlorate, then convert the NaClO4 to KClO4 or NH4ClO4 the usual way.

But where would I get pure magnetite... sigh.

rikkitikkitavi - 30-4-2004 at 15:29

you can use carbon anodes for ClO3-, but they will erode , making filtering of the solution necessary.

/rickard

axehandle - 30-4-2004 at 15:45

That's why I don't want to use graphite. Magnetite looks very promising. I imagine (it being magnetic) that one could construct an electrode simply as a powerful electromagnet made out of a coiled mild steel 8mm rod, covered with a 20mm thick layer of magnetite. Perhaps mixed with a small quantity of some inert binder.

Anyways, my trusty pottery supplier claims to have "black iron oxide", but lists it formula as Fe2O3. I've sent them an email pointing out the impossibility of that. It should probably be "FeO.Fe2O3", but they are (luckily for me) not good at chemistry. The only two iron oxides I know of that are black are FeO and Fe3O4. FeO is more or less explosive and highly unstable, so it's likely that their web catalogue has a misprint. But I won't get any reply until Monday. *sniff*

I hate waiting.

[Edited on 2004-5-1 by axehandle]

t_Pyro - 30-4-2004 at 18:01

Er... Don't you think you set your sights a bit too high? 5 Kg of perchlorate a week? You could be rich in no time if you could sell that off!!

You might want to try coating your graphite electrodes with lead dioxide using a lead nitrate electrolyte, as mentioned on Wouter's page. Graphite electrodes coated with lead dioxide in this manner can be used in place of platinum electrodes in a chlorate/ perchlorate cell.

axehandle - 1-5-2004 at 01:15

Quote:

Er... Don't you think you set your sights a bit too high? 5 Kg of perchlorate a week? You could be rich in no time if you could sell that off!!

More like: I'd save alot of money in notime. But you're right, perhaps I should (in the interest of science) turn capitalist on a small scale. Could be meself a lathe or some other toy.
Quote:

You might want to try coating your graphite electrodes with lead dioxide using a lead nitrate electrolyte, as mentioned on Wouter's page. Graphite electrodes coated with lead dioxide in this manner can be used in place of platinum electrodes in a chlorate/ perchlorate cell.

There's no way I'd get hold of lead nitrate, both lead salts and nitric acid are restricted here. Magnetite is supposed to work fine for chlorates though, chlorates can be thermally decomposed to perchlorate and chloride, NaCl is cheap...

chemoleo - 1-5-2004 at 19:50

arrgh...
wasnt there another thread pointing out precisely how to get lead dioxide from lead and copper carbonate/acetic acid? Comon!!
You dont HAVE to have the nitrate, the acetate is fine... as shown by my very own experiment... why do I bother? :( :(

PS or am I misunderstanding something? It's late here...

[Edited on 2-5-2004 by chemoleo]

axehandle - 2-5-2004 at 05:59

It could be me misunderstanding something, I have a grade 9 hangover.

axehandle - 2-5-2004 at 12:48

Quote:

arrgh...
wasnt there another thread pointing out precisely how to get lead dioxide from lead and copper carbonate/acetic acid? Comon!!
You dont HAVE to have the nitrate, the acetate is fine... as shown by my very own experiment... why do I bother?

PS or am I misunderstanding something? It's late here...

Ah. No. I'm not abandoning the PbO2 idea, I'm just speculating idly about using Fe3O4 as an anode in a VERY big chlorate cell. The PbO2 would then be used in a chlorate-->perchlorate cell. Or, I'd build a chloride-->perchlorate cell using a huge PbO2 anode. I know mind-reading is hard, I don't always explain how I think. The magnetite speculation was actually about trying the substrate-less PbO2 anode manufacturing process using much more easily obtained Fe3O4 as a replacement, until I find a method that works. Then I would duplicate it using PbO2. You have not helped me in vain, I just have a tendency to speculate wildly, not explaining why or what I'm speculating about...

Edit: I've just ordered 1kg of copper carbonate to experiment with.

[Edited on 2004-5-3 by axehandle]

garage chemist - 15-9-2004 at 06:39

I will soon purchase some platinum wire
(diameter: 0,3mm length: 45cm price: 30€. Quite a good deal.).
I will also buy a platinum coated Titanium anode when I have the money.

I've read that trace amounts of chloride can dissolve platinum when it's the anode! How severe is this problem? Does my NaClO3 need to be free of chloride when producing perchlorates? I will use 99% pure NaClO3 (store- bought) as the starting material.
No NaCl, the process would take way too long.

Generally, which ions dissolve platinum when it's the anode?

Another question: axehandle, how did you make a non- corroding electrical connection to the Ti/Pt anode? I've been wondering about that for a long time.
The Ti/Pt anodes that I sometimes see at Ebay are just Pt coated Ti wire meshes and look exactly like yours. They have no electrical connectors. Did your anode have connectors, or did you have to make them?

axehandle - 15-9-2004 at 09:55

This was before I abandoned the Pt anode and decided to build a PbO<SUB>2</SUB> anode instead, but here goes: My pesky Pt-ized Ti anode has a Ti plate with a hole through it welded to the Ti mesh. I made a connection simply by threading a copper wire through the hole in a few loops and then winding it tight. Corrosion there is a non-problem since the connection will never be subjected to fluid from the cell.

If the connection were to be subjected to cell fluids, the only suitable connection material I know of is silver. The connection will corrode there too, but the corrosion products are conductive so the connection won't fail.

From what little I've read, corrosion of the Pt is non-negligible when it's used in a chlorate cell and the chloride content gets low. Seems the corrosion is minimal when used in a pure perchlorate cell. Don't quote me on this though, I could be very wrong.

[Edited on 2004-9-15 by axehandle]

garage chemist - 21-6-2005 at 13:59

I want to share this excellent link on the home production of chlorates and perchlorates, I'm sure that nobody posted it before (at least I've never seen it before):

http://www.vk2zay.net/article.php/63

Very interesting!

EDIT: OK, it's not that big, I posted it before reading through it... but the rest of the site is also good.

[Edited on 21-6-2005 by garage chemist]

Mjor Factor!!

SAM4CH - 17-6-2006 at 14:25

What is the major factor which is respond of converting chlorate to perchlorate when we try to make perchlorate directly from chloride by electrolysis, Is it current density at anode or chloride concentration (<10%), and when we use low current density on special anodes like MMO which has optimum current density=(20A/ft2) and it is stable at low chloride concentration (>3000ppm Chloride) Can I get perchlorate!!?

SAM4CH - 30-8-2006 at 13:00

How can I make perchlorate from NaCl using pure platinum with out corrision? I have platinum plate 10*20 cm with 1mm thickness, it is very expensive so please advise me!!

jpsmith123 - 30-8-2006 at 13:51

In theory, in order to minimize platinum loss, you don't want to do a "batch" type process; rather, you want a "continuous" process.

So in practice you want to do it in two steps, where you first make chlorate (maybe using an immersed polyester bag filled with salt to maintain a saturated NaCl solution, adding water as necessary), and then take your product chlorate and electrolyze that in the same manner.

FrankRizzo - 1-9-2006 at 19:09

Would anyone here happen to have access to The Journal of Applied Electrochemistry? My university has access through Springerlink.com, but only for issues released since '92. I would love to read the following articles:

Large-scale preparation of perchlorates directly from sodium chloride

Insoluble anode of porous lead dioxide for electrosynthesis: preparation and characterization

Kinetics and mechanism of anodic oxidation of chlorate ion to perchlorate ion on lead dioxide electrodes

Insoluble anode of α-lead dioxide coated on titanium for electrosynthesis of sodium perchlorate

The preparation and behaviour of magnetite anodes

simple - 14-11-2006 at 15:46

Quote:
Originally posted by SAM4CH
How can I make perchlorate from NaCl using pure platinum with out corrision? I have platinum plate 10*20 cm with 1mm thickness, it is very expensive so please advise me!!


If you will apply current to the plate it will detoriate over the periud of time. anode and cathode are always sacraficial part. There are technics to prolong there's live but they will still havenominated lifespan

simple - 14-11-2006 at 15:55

axehandle , I have only partially read and understand what you are trying to do, but just want to comment to be careful with rising temperature of the reaction vessel. If you are using Ru oxide based anode it is VERY sensitive to operating temperatures and will wear out rapidly. I know as we manufacture those.