Author Topic: electrolysis of phosphoric acid  (Read 2759 times)

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  • Guest
electrolysis of phosphoric acid
« on: January 10, 2003, 12:54:00 AM »
This is something I found in a 1930´s chemistry book a couple of days ago:

"Dill obtained phosphorus by electrolisys of hot 65% phosphoric acid mixed with 20-25% of powdered carbon using 80-150Amp and 120V(...)"

Unfortunately the book gives no further references, other than the name at the beginning of the quote. Maybe there´s a patent somewhere. we just have to search.
Anyway, the information here is enough for the curious(and cautious) experimenter to develop a working procedure so I thought I post it here.


  • Guest
wouldn't that bee a dream worth dreaming ...
« Reply #1 on: January 10, 2003, 01:57:00 AM »
wouldn't that bee a dream worth dreaming ...

Pinky, are you pondering what Im pondering?
 I think so brain but a show about two talking lab'll never get on the air... NarF*


  • Guest
U * I = P
« Reply #2 on: January 10, 2003, 03:14:00 AM »
120 volts and 125 amps make 15 kilowatts! Do you really want to do this?


  • Guest
Shit! Sorry for the fuck-up.
« Reply #3 on: January 10, 2003, 03:32:00 AM »
Shit! Sorry for the fuck-up.
Didn´t see that little flaw in the procedure. That´s definitely nothing to mess with.


  • Guest
that would p;robably blow your service Xfmr
« Reply #4 on: January 10, 2003, 04:10:00 AM »
Most people don't have service transformers rated for that much running to their house unless they are in residential areas.  Even then, you'd blow the transformer if the rest of the customers were drawing a moderate load.


  • Guest
My CAD$0.02
« Reply #5 on: January 10, 2003, 10:09:00 PM »
Surely current is relative to batch size?  I think it's worth a shot... 10% phosphoric acid is OTC here, concentrate that and give it a go...  one amp ought to produce something given enough time, if this works at all...

One warning to others who might attempt this, 120V is not safe to play with...  is electrolysis always done using DC (do we care if the ions change direction 100 or 120 times a second)?  If so, you'd need to rectify the mains current using suitably rated diodes (1N4004 diodes are very common, cheap, rated for 1A 600V), and even then you have a problem, AC at 120V has peaks of +/- 168V, so once rectified you now have 168V DC (peak that is - the average would still be 120V, unless you put a capacitor across it or something).  Also, limiting the current to 1A could be a challenge...


  • Guest
Yeah but
« Reply #6 on: January 10, 2003, 11:45:00 PM »
considering the current and th voltage, it seems that there is more to it than having enough voltage to drive an electrolysis, heat for example. A reference might answer the question... a literature search could prove interesting, at least.


  • Guest
Arc Furnace
« Reply #7 on: January 11, 2003, 01:09:00 AM »
This just sounds like a basic arc furnace, not electrolysis in the traditional sense.  I think this is doable, however if I were to try it, I would use a phosphoric acid salt instead of the free acid.

This page would probably bee a great place to start for bee'z interested in making their own arc furnace.  Its about how to build a homemade arc welder.

This could be even better for the home phosphorus maker, how to make a high temperature electric crucible.

Here is a guide to crucible selection and installation, very handy!

Report back on any success you have.


  • Guest
Alternative methods from fertilizer?
« Reply #8 on: January 12, 2003, 11:17:00 PM »
Has anyone tried getting phosphorus out of the P2O5 in fertilizer? A search showed that some people thought it would be possible, but I wasn't able to find anyone who'd tried it.

It doesn't seem to have an insanely high melting point, perhaps electrolysis on it would be workable? Or would the heat necessary cause detonation, or unwanted conversion to black phosphorus?

Further complicating the issue is that there seems to be some debate as to whether it's P2O5 or P4O10 in fertilizer. Does anyone know?


  • Guest
on the wrong track
« Reply #9 on: January 13, 2003, 03:02:00 AM »
There is no P2O5 or P4O10 (however you like to write your phosphoric anhydride) in fertilizer. Neither is there any K2O in there. The exact reasons for representing nutrient content in fertilizers based on compounds that never appear in fertilizer are unknown to me. The closest things you will find in fertilizers are phosphates, and it is non-trivial to produce usable quantities of phosphorus from phosphates with lab equipment.


  • Guest
If you soak Acivated carbon in Phosphoric acid
« Reply #10 on: January 13, 2003, 01:41:00 PM »
If you soak Acivated carbon in Phosphoric acid overnight,and then bake it at 400deg c+ for a few hours,and then rinse of any excess acid,within the pores of the carbon will be trapped elemental phosphorus @ 2-5% by carbon weight(depending on pore size).

Add this to the fact that under the right circumstances activated carbon will produce HI from water and iodine,and I think the whole need for red Phosphorus as we know it can be circumvented.

Either concider that,or think of a way to liberate that phosphorus loading from the carbon support which IMO seems less of a task then reaching the dizzy temps needed to reduce phosphate,and the hazards involved with this.

Anyway,this has nothing to do with electrolysis.But worth more attention.



  • Guest
ballz do you have a reference or anything to...
« Reply #11 on: January 13, 2003, 07:50:00 PM »
ballz do you have a reference or anything to back-up that statement?


  • Guest
No not the statement as a whole.That was just...
« Reply #12 on: January 13, 2003, 09:21:00 PM »
No not the statement as a whole.That was just another of my wacky ideas.But the inspiration comes not from my mind.

See these posts for patents regarding the first two sentences of the above post.

Post 356219 (missing)

(ballzofsteel: "Sorry if this is dumb.", Stimulants)
Carbon/phosphorus composite

Post 395923 (missing)

(ballzofsteel: "HI from Activated carbon + I2", Stimulants)
Activated Carbon HI

The rest is pure fantasy.


  • Guest
« Reply #13 on: January 26, 2003, 11:42:00 PM »
I don't remember the number but there is a patent using microwave oven type energy for turning phosphoric acid into a more desirable type of substance.

Will try to post said number if i can remember where i live let alone what my name is. -- was.


  • Guest
here 'tis
« Reply #14 on: January 27, 2003, 12:27:00 AM »

Patent US6207024

  Method of preparing phosphorus

A method of producing phosphorus in which a mixture of phosphoric acid and carbon reductant is exposed to microwaves at a power level sufficient to heat the mixture to a temperature at which phosphorous is produced. This method can be carried out at lower temperatures than conventional phosphorous production and does not give rise to the solid waste normally formed in conventional phosphorous production. The phosphorus thus formed can be converted back to phosphoric acid, thus effecting purification of the phosphoric acid

enjoy and stay in touch if this produces a waxy substance and a weird sensation in your jaw.


  • Guest
current linit with ease
« Reply #15 on: February 21, 2003, 06:07:00 AM »
rectify with forementioned diode and filter with capacitor of sufficient working voltage, then run filtered V through the appropriate series resistor.

 Value in ohms will determine the max current allowed and maked sure that the power rating of the Resistor will handle the heat that will be dissapated.


  • Guest
Ah, an old hobby comes back to haunt me...
« Reply #16 on: March 06, 2003, 08:09:00 AM »
Well, yes, that's the easy way to do it, but the actual voltage presented at the electrodes will vary with this method.  Depending on the resistance chosen, most of your energy could be getting sucked up by the resistor, significantly lowering the voltage across the electrodes.  Not a problem if you know how much you're losing so you can tweak the supply voltage, put a volt meter across the resistor while it's in operation to see how much is getting lost there...


  • Guest
200AMP Service
« Reply #17 on: March 09, 2003, 07:15:00 AM »

Most people don't have service transformers rated for that much running to their house unless they are in residential areas.  Even then, you'd blow the transformer if the rest of the customers were drawing a moderate load.

Where do you live that 200AMP Service to your house isn't the standard? Some low budget areas were developed with  only 125AMP main breakers, but this can almost always be upgraded for a few hundred dollars. This is a must have upgrade to your house if you have interesting hobbies like vaporizing screwdrivers and assorted metal kitchenware items. Tuesday nights would never be the same around my house if 120AMPs would cause problems in the local transformers.


  • Guest
« Reply #18 on: April 04, 2003, 09:38:00 AM »
Has anyone made any progress with the possibility of electrolysis as a route to RP? Is there a consensus that this is at least worth looking into further?

On a related note, does anyone have any ideas on ghetto rectification of HV at high current? Traditional HV DC power sources are pricey.