RECOVERY OF LEAD FROM CAR BATTERY SCRAPS.

Hi

This is my first post on this forum.


I remember reading from a very old school science review years ago, that lead(IV) oxide, PbO2, is insoluble in NaOH,, but interestingly if you add sucrose, basically sugar, the PbO2 will dissolve in the solution, forming a yellowy /brown solution.

Spongy lead can be obtained by electrolysis of the solution.

I did do this experiment, on a small scale from an old wrecked car battery i scavenged, and it does work.
The sponge of lead easily oxidised to yellow Lead (II) oxide when heated in an evaporating basin.

Wonder what sort of compound the Pb must be forming with the C12 H22O11 then.....?

I think the review was as old as 1986, i had only 4 of them, which i scavenged from the science class bin, and that was about 10 years ago.

I think i still have them, in a cupboard. Ill need to look for them, look it up in whatever book it was.
Ill get back to this thread if i find them.

Whether or not the oxidation state of the lead in the oxide mattered in the dissolving into the NaOH....I dont know..... if lead oxides are amphoteric enough to behave like Al and Zn oxides.

I suspect that the lead might have been forming some sort of soluble organic compound with the sucrose.
I think the main point of the article was that Pb was easily extracted from car battery scrap using very cheap, and readily available chemicals.

I mean you could scavenge lots of old lead/acid batteries and do this in BIG bulk in your back yard, very cheaply........ sell on the lead.

Quote: Originally posted by MR AZIDE

I did do this experiment, on a small scale from an old wrecked car battery i scavenged, and it does work.

Quote: Originally posted by blogfast25

Aresulting Pb (II) oxide/hydroxide would dissolve in NaOH, as sodium plumbite

Quote: Originally posted by Hexavalent

Do you have a reference for this? I found the aforementioned SSR. Sep 1986, Volume 68, No 242, on page 91 to 93. ISSN 0036-6811. It starts off by saying how lead gan be removed from accumulator scrap, and then goes on with some experiments concerning the solubility of lead salts obtainable from accumulator scraps in NaOh soln. PbSo4 + 4NaOH ---> Na2Pb(OH)4 + Na2So4 The lead sulphate dissolves in the 20% NaOH soln, with gentle heat to give a soln of lead hydroxy plumbate, and sodium sulphate. Lead (II) Oxide dissolves also, but more slowly, BUT ONLY when the sugar is added. The Lead (IV) Oxide will only dissolve as well when sugar is added, but also ( i forgot about this bit) with the evolution of H2 gas.......! They go on to say , very interestingly that the solubility of these lead oxides improves as the number of hydroxyl groups on the polyglycols or sugars increases. They claim that the lead (ii) oxide forms complexes, and the lead (iv) forming lead (ii) as it oxidises the sugar. They have listed that the recovery is as follows. 5g of PbO2 and 7g of PbSO4 are added to 200ml water which has has previously 45g cane sugar and 32 g NaOH dissolved. The solution is heated to boiling, with stirring, until all had dissolved, with evolution of gases, untill a clear red solution forms. After cooling the soln, is electrolyzed using graphite electrodes, while stirring, and the current is maintained at about 500mA throughout. The Pb formingas a spongy mass at the Cathode, and O2 at the anode. Says that the solution needs to be electrolizes ASAP as insoluble lead compounds crystallize. Adding borax to the spongy lead allows it to be melted into solid lumps, and the borax protects from the oxidation . I did try this much the same as described those years ago, but didnt add any of the lead sulphate, and was just done in small scale, without weighing out etc....... The interesting bit was that The sponge of lead produced easily oxidised in air while heating to form yellow lead(ii) oxide......... but to its large surface area.

Well, well, well.

After cooling, standing overnight, slight dilution and cold filtering I obtained a slightly syrupy liquid with a slight brownish tint (but clear). The brown tint is caramelised sugar, I think.

To this filtrate about 10 ml of glacial acetic acid was added and low and behold a creamy white precipitate dropped out: ‘quite a bit’ too. See 3 TTs with that slurry in’em (sorry about the poor focus):



Below: the tubes above with:



a) Left: 70 % HNO3 added. Precipitate mostly dissolves but not all.
b) Middle: excess glacial acetic added, not much change noted
c) Right: with bleach added (NaClO): precipitate turns orangy/red

Below:



Here K2Cr2O7 solution was added to the supernatant liquid of the left tube in the photo right above. No lead (II) chromate formed because residual sugar reacted with dichromate, hence the Cr3+ blue colour.

Additional tests (no images) on the straight slurry: 9 % H2O2 caused fizzing and precipitate turned brown. Adding 36 % HCl caused precipitate to change texture: I believe white PbCl2 was being formed.

In conclusion, all this strongly points to significant (but not large) amounts of battery lead to have gone into solution as sodium plumbite (II) [Na₂Pb(OH)₄].

Is all this explainable by lead's weak amphoterism alone?



[Edited on 1-6-2012 by blogfast25]

[Edited on 1-6-2012 by blogfast25]

the brownish tint, may be some sort of soluble complex of the sugar and lead.

you would expected lead acetate to form adding acetic acid, but lead acetates are very soluble, so you maybe made a very concentrated solution, and hence a lead acetate slurry formed......or its something else.......
Have you tried recrystallizing the initial white slurry, to see if you can get lead acetate crystals?.

I think HNO3 would dissolve the lead acetate( or whatever that white slurry is) and make at least some lead nitrate, maybe it didnt all dissolve due to some common ion effect.

did you get any fizzing / Cl2 when you added the hypochlorite.......? I think the hypochlorite has reaced with the white slurry, and produced a precipitate of lead(ii) oxide....???

The H2O2 fizzing mustve been O2 gas, as it was oxisiding the white slurry, i think the brown precip was possible lead (iv) oxide (PbO2.
I agree with the texture chance...PbCl2......

Interesting things going on there blogfast.....

Quote: Originally posted by MR AZIDE

you would expected lead acetate to form adding acetic acid, but lead acetates are very soluble, so you maybe made a very concentrated solution, and hence a lead acetate slurry formed......or its something else.......