Sciencemadness Discussion Board - Eletrolysis with chlorides to perchlorate.

Eletrolysis with chlorides to perchlorate.

KonkreteRocketry - 25-2-2013 at 09:51

I want to make perchlorate from chlorides.

I have lithium salt LiCl and Sodium Salt NaCl.

My electrolysis is powdered by an old computer charger with 20Volts.

The temperature of the cell is around 25 degree Celsius.

Any one of you have any idea how long it will take me to get perchlorate at this rate ? and how to i make sure that it is perchlorate ?

My anode is Iron, it will rust, but i can filter the perchlorate out since they dissolve in water and rust dont and so how long it shall take ? maybe few days ?

Also, i heard eletrolysis of LiCl is trihydrate is that true ? if it is, how to anhydrate it ?

elementcollector1 - 25-2-2013 at 10:09

...None of this will work. Absolutely none of it.
Iron anode = no perchlorate. Not even chlorate, probably. Ferrate? Maybe.
20V = how many amps? Amps determine speed of electrolysis.
25 degrees C = way too low. IIRC, the temperature for perchlorate production was somewhere around 60 C.
chloride -> perchlorate = Wasteful. Convert it to chlorate first, that'll get you better product.

"electrolysis of LiCl is trihydrate" = And...? It doesn't matter how many water molecules you have if you're dissolving it in water.
Besides, where'd you even get LiCl?

KonkreteRocketry - 25-2-2013 at 10:14

Quote: Originally posted by elementcollector1

...None of this will work. Absolutely none of it.
Iron anode = no perchlorate. Not even chlorate, probably. Ferrate? Maybe.
20V = how many amps? Amps determine speed of electrolysis.
25 degrees C = way too low. IIRC, the temperature for perchlorate production was somewhere around 60 C.
chloride -> perchlorate = Wasteful. Convert it to chlorate first, that'll get you better product.

"electrolysis of LiCl is trihydrate" = And...? It doesn't matter how many water molecules you have if you're dissolving it in water.
Besides, where'd you even get LiCl?

Ok i have a graphite, aluminum, and copper anode also, i can keep it 30 degree.

[Edited on 25-2-2013 by KonkreteRocketry]

elementcollector1 - 25-2-2013 at 12:15

Graphite will work to convert to chlorate, and those other two will not.
Then, once you have chlorate, recrystallize for purity and electrolyse a clean solution of that, and you might get perchlorate.

hissingnoise - 25-2-2013 at 12:53

Quote:

]I want to make perchlorate from chlorides.

Then a bit of reading up on the subject is called for, I'd say . . .

woelen - 25-2-2013 at 13:59

Making chlorates from chlorides already is not trivial, but it can be done at home. But you need suitable electrodes and a fairly powerful power supply, which works at appr. 5 volts (not 20 V!!) and is capable of delivering at least a few amperes. Temperature is another issue. It is not a matter of having a cold cell, the cell will easily be too hot. You may need cooling.

I have made a write-up on making KClO3 from KCl, using MMO-anodes in a miniature cell.

http://woelen.homescience.net/science/chem/exps/miniature_ch...

As the web page shows, the making of chlorates is not really trivial. You can use graphite instead of MMO, but then the liquid will become totally black and it will be quite difficult to purify your chlorate. In that case you'd better start with NaCl instead of KCl, allowing easier separation of all the carbon from the sodium chlorate.

Making perchlorates at home is MUCH more difficult, unless you have a lot of money to spend on platinum electrodes or are willing to make your own PbO2-anodes from lead nitrate and an MMO-substrate.

MMO-mesh can be purchased at eBay (the following link is just an example, there are more MMO items on eBay):

http://www.ebay.com/itm/5-x-1-Expanded-Titanium-with-MMO-Coa...

testimento - 12-7-2013 at 18:46

I have a transformer that uses 240VAC mains 20A and outputs 7VAC 685A. This is regulated with triac to 2 or 3.5kW MAX. I have four 400A rectifiers which decrease the voltage by two units at least when operated and the factual DC output is 4V max at full power, so it looks like I have to rewind the secondary once again to get it to at least 5VDC for perchlorates.

I was planning on using a pack of PbO2 coated lead sheet electrodes 3mm thick, 20pcs, with 1020 carbon steel cathodes placed every next to other to create (+-+-+-+) combo, because the electrolysis efficiency seems to be best with smallest gap. The contactor surfaces are aluminium bars that are connected each to the main rail.

Manifest - 13-7-2013 at 03:08

You can convert Chlorate to Perchlorate by adding Hydrogen Peroxide in an acidic environment so it reduces.

So you'll first need to make chlorate, this seems to be the easiest method and you're guaranteed high purity as long as your chlorate is pure.

plante1999 - 13-7-2013 at 03:49

Quote: Originally posted by Manifest

You can convert Chlorate to Perchlorate by adding Hydrogen Peroxide in an acidic environment so it reduces.

So you'll first need to make chlorate, this seems to be the easiest method and you're guaranteed high purity as long as your chlorate is pure.

It does not work this way, why does everyone think it does?

The real way is to melt potassium chlorate for a few hours, and leach potassium chloride with water. It is a traditional procedure in old textbook.

[Edited on 13-7-2013 by plante1999]

Manifest - 13-7-2013 at 04:22

Quote: Originally posted by plante1999

It does not work this way, why does everyone think it does?

I was told that it works this way in an acidic environment.

Also, this is why.. https://www.youtube.com/watch?v=9YVsEX-ikUQ

Also, I would advise caution in doing it that way you are heating an oxidizer.

You would need to control the temperature or it will decompose so it doesn't seem very practical for an amateur.

[Edited on 13-7-2013 by Manifest]

Metacelsus - 13-7-2013 at 05:01

The point is that it decomposes and in doing so disproportionates: 4 KClO3 -> 3 KClO4 + KCl (ideally, but in real life some O2 may be lost)

AndersHoveland - 13-7-2013 at 18:22

Quote: Originally posted by plante1999

The real way is to melt potassium chlorate for a few hours, and leach potassium chloride with water. It is a traditional procedure in old textbook.

I had read about this in an old pyrotechnics forum. In a glass test tube over a flame, you hold the heat just below the decomposition point, allowing the chlorate to disproportionate into perchlorate and chloride.

Using steady and even application of heat, supposedly the molten potassium chlorate starts to paradoxically solidify, since the melting point of the perchlorate is higher than the chlorate.
If the molten chlorate starts giving off bubbles, it means that the chlorate is too hot and decomposing into oxygen, and the heat should be reduced.

To get rid of the remaining chlorate, hydrochloric acid is added. This reduces the chlorate to chloride but leaves the perchlorate alone. Then the much less soluble perchlorate can be crystallized out of the solution.

Another similar method:

Fowler and Grant found that on heating chlorate with silver oxide that the chlorate was completely converted to perchlorate without loss of oxygen, metallic silver also forming.
J. Chem. Soc. 57, 272 (year 1890)

[Edited on 14-7-2013 by AndersHoveland]

bfesser - 13-7-2013 at 19:21

AndersHoveland, I've never had much interest in chlorates and perchlorates—perhaps because I don't pursue energetic materials—but what you've described is fascinating! Unfortunately, I can't experiment here, but I may see what I can dig up (if anything) in the literature on what you have described. I'd be delighted to see some photos of this, if anyone wants to safely try it in microscale. woelen's a good photographer and practitioner of test tube reactions. I wonder if he'd be willing to do this for science!

testimento - 13-7-2013 at 22:47

Quote: Originally posted by AndersHoveland

To get rid of the remaining chlorate, hydrochloric acid is added. This reduces the chlorate to chloride but leaves the perchlorate alone. Then the much less soluble perchlorate can be crystallized out of the solution.

[Edited on 14-7-2013 by AndersHoveland]

As far as I know, ammonium perchlorate industry uses the HCl method in a large scale to convert perchlorates into perchloric acid(and then bubble ammonia through the solution to precipitate AP). Removing the chlorates with small amounts of HCl can be done when the perchlorate(preferable sodium) is dissolved in water, and the chlorate is released as chlorine dioxide and the solution turns red, and when heated, it will release the gas and become clear again.

AndersHoveland - 14-7-2013 at 12:52

Quote: Originally posted by KonkreteRocketry

I want to make perchlorate from chlorides.

I read one investigation where they found that ozone could oxidize chloride to perchlorate, though the reaction was very inefficient. Very interestingly, they found that it was impossible to oxidize chlorate to perchlorate with ozone.

In water, the yield of perchlorate from treating ozone with chlorite is only 2.7%, the remainder only gets oxidized to chlorate.
"Perchlorate Formation by Ozone Oxidation of Aqueous Chlorine/Oxy-Chlorine Species: Role of ClxOy Radicals",
Balaji Rao, Todd A. Anderson, Aaron Redder, W. Andrew Jackson, Environ. Sci. Technol., 2010, 44 (8), pp 2961–2967

"exposing aqueous solutions or Cl(-) coated sand or glass surfaces to O3 (0.96%) generated ClO4(-) with molar yields of 0.007 and 0.01% for aqueous Cl(-) solutions and 0.025 and 0.42% for Cl(-) coated sand and glass, respectively. Aqueous solutions of Cl(-) produced less ClO4(-) than Cl(-) coated sand or glass as well as a higher ratio of ClO3(-) to ClO4(-). "
...
"a ClO2(-) solution exposed to O3 produced substantial molar yields of ClO4(-)" (4% molar yield).

"Perchlorate production by ozone oxidation of chloride in aqueous and dry systems", N. Kang, W.A. Jackson, P.K. Dasgupta PK, T.A. Anderson

In other words, only very small traces of perchlorate are formed by oxidizing chloride with ozone. The investigation did not find any traces of perchlorate when chlorate was treated with ozone.

I think it should also be pointed out here that ozone can oxidize gaseous ClO2 to Cl2O6, a hazardous red fuming liquid. In this case, the reaction probably proceeds much more readily because ClO2 is a molecular radical (similar to NO2).

[Edited on 14-7-2013 by AndersHoveland]