Sciencemadness Discussion Board

PbSO4 to H2SO4

LookingForAnswers - 4-5-2024 at 15:35

Hello there. All sings on earth and heaven tell me that i fucked electrolysis of CuSO4 and as by product i have lots of white smooth powder easy solving in hot sulph acid. Propably it is PbSO4. My question is: Can i electrolysis it in diluted h2so4 on both lead electrodes to reduce a lead cation and get back my acid ?


[Edited on 4-5-2024 by LookingForAnswers]

[Edited on 4-5-2024 by LookingForAnswers]

[Edited on 4-5-2024 by LookingForAnswers]

bnull - 4-5-2024 at 17:34

Quote: Originally posted by LookingForAnswers  
My question is: Can i electrolysis it in diluted h2so4 on both lead electrodes to reduce a lead cation and get back my acid ?

Well, you can make a miniature (2 V?) lead-acid cell and charge it: products are lead on anode and lead dioxide in cathode. It's easier said than done, of course. Take a look at Linden's Handbook of Batteries.

khlor - 5-5-2024 at 18:26

Quote: Originally posted by LookingForAnswers  
My question is: Can i electrolysis it in diluted h2so4 on both lead electrodes to reduce a lead cation and get back my acid ?


Yes, but you should use graphite on the anode(either that or platinum). For the cathode you can use lead. since it is dilute h2so4 you should be fine on the electrodes, just know that graphite anodes do tend to exfoliate, but will not react with h2so4, so, you wil remove the lead, but probably will get a somewhat dirty h2so4, decantation can fix most of it.

Sir_Gawain - 5-5-2024 at 20:52

Quote: Originally posted by LookingForAnswers  
Hello there. All sings on earth and heaven tell me that i fucked electrolysis of CuSO4 and as by product i have lots of white smooth powder easy solving in hot sulph acid. Propably it is PbSO4.
How did so much lead get into your electrolysis cell? Were you using lead electrodes?

LookingForAnswers - 6-5-2024 at 16:01

Quote: Originally posted by khlor  
Quote: Originally posted by LookingForAnswers  
My question is: Can i electrolysis it in diluted h2so4 on both lead electrodes to reduce a lead cation and get back my acid ?


Yes, but you should use graphite on the anode(either that or platinum). For the cathode you can use lead. since it is dilute h2so4 you should be fine on the electrodes, just know that graphite anodes do tend to exfoliate, but will not react with h2so4, so, you wil remove the lead, but probably will get a somewhat dirty h2so4, decantation can fix most of it.


I havent been on forum since I added that post and today i began do it on leads(both) electrodes. fortunetly i stop it when the solution start do a lot of white foam. unfortunetely it looks worse than before. my plan is: fractional freezing to collect remaining acid, this white pulp flush with distiled water , than filter under vacum and follow your instructions but the question is: what concentration would you use for electrolysis with graphite?

LookingForAnswers - 6-5-2024 at 16:09

Quote: Originally posted by Sir_Gawain  
Quote: Originally posted by LookingForAnswers  
Hello there. All sings on earth and heaven tell me that i fucked electrolysis of CuSO4 and as by product i have lots of white smooth powder easy solving in hot sulph acid. Propably it is PbSO4.
How did so much lead get into your electrolysis cell? Were you using lead electrodes?


i couldnt get completely colorless solution of my acid, ive begun do a research for a solution this problem. I found somewhere in web the prompt is possible to rise up conductivity by adding vinegear, propably i added much too much, another thing is too high current I set up and if you combine these two fails you receive what i received.. :/

[Edited on 7-5-2024 by LookingForAnswers]

khlor - 7-5-2024 at 00:51

Quote: Originally posted by LookingForAnswers  
Quote: Originally posted by khlor  
Quote: Originally posted by LookingForAnswers  
My question is: Can i electrolysis it in diluted h2so4 on both lead electrodes to reduce a lead cation and get back my acid ?


Yes, but you should use graphite on the anode(either that or platinum). For the cathode you can use lead. since it is dilute h2so4 you should be fine on the electrodes, just know that graphite anodes do tend to exfoliate, but will not react with h2so4, so, you wil remove the lead, but probably will get a somewhat dirty h2so4, decantation can fix most of it.



I havent been on forum since I added that post and today i began do it on leads(both) electrodes. fortunetly i stop it when the solution start do a lot of white foam. unfortunetely it looks worse than before. my plan is: fractional freezing to collect remaining acid, this white pulp flush with distiled water , than filter under vacum and follow your instructions but the question is: what concentration would you use for electrolysis with graphite?


Oh no, it seems that much of your acid became lead sulfate (the white foam) lucky you that stuff isn't that much soluble in water, lead chemistry is hazardous and soluble lead compounds are the worst.
if I were you, I'd try to react the white foam with zinc powder, that would result in metalic lead and zinc sulfate(soluble) then after filtering the solution, start electrolysis with graphite anode and zinc cathode. it be interesting, but not sure it it is worth the work and zinc used. but at the end, in theory you'd get metalic lead powder, metalic zinc and a not so pure dilute sulfuric acid solution.

As for your question, I did had success with copper sulfate solutions resulting in up to almost 20% w/v acid, not pure but usable for some non critical experiments and cleaning.

LookingForAnswers - 7-5-2024 at 05:18

i thought about decompose it to PbO and SO3 , then pass sulphur trioxide throught remained acid, the problem is themperature of the decomposing. Wiki says that PbSO4 need over 1000*C , in theory i can do it but ive read somewhere that so3 decompose to so2 over 600*C, so it dosent have any sense. I dont have zinc at this moment but i found another possible way with tin which i have a lot. Wiki says:

" Reaction between tin tetrachloride and sulfuric acid in a 1:2 molar mixture at near reflux (114°C):
SnCl4 + 2 H2SO4 → Sn(SO4)2 + 4 HCl
Pyrolysis of anhydrous tin(IV) sulfate at 150°C - 200°C:
Sn(SO4)2 → SnO2 + 2 SO3"

Sulphur trioxide produced this way id pass throught h2so4 but i dont do anything before someone more experienced confirm it.


Rainwater - 7-5-2024 at 10:39

Of you want to use the thermal decomposition route may i suggest a single displacement reaction first.
Lead sulfate is more solubility in molten lead than liquid water, but both solvents will work. Water being much much slower
$$ PbSO_4 + Fe \rightarrow FeSO_4 + Pb $$

How I manage lead waste is by converting it into the sulfate and placing it into a bucket with scrap iron, acidified the bucket with sulfuric acid (any ph below 5-6) to drive off the Cl from any chloride salts. And let it sit at about 23c for a few weeks with a bubbler.

Afterwards, filter the solution(test then discard), melt the sludge down and scrape off the slag amd pour it into a cone mold. This reduces the amount of lead waste. By isolating the free metal.
The slag and cone plug, are then stored for the next batch.
To fully recover all the lead, the slag and plug are melted with extra lead and more iron. For about 15 minutes at 400c. The liquid is poured into shot and the soluble iron sulfate allowed to disolve, leaving 95%+ pure lead.

LookingForAnswers - 7-5-2024 at 11:56

Quote: Originally posted by Rainwater  
Of you want to use the thermal decomposition route may i suggest a single displacement reaction first.
Lead sulfate is more solubility in molten lead than liquid water, but both solvents will work. Water being much much slower
$$ PbSO_4 + Fe \rightarrow FeSO_4 + Pb $$

How I manage lead waste is by converting it into the sulfate and placing it into a bucket with scrap iron, acidified the bucket with sulfuric acid (any ph below 5-6) to drive off the Cl from any chloride salts. And let it sit at about 23c for a few weeks with a bubbler.

Afterwards, filter the solution(test then discard), melt the sludge down and scrape off the slag amd pour it into a cone mold. This reduces the amount of lead waste. By isolating the free metal.
The slag and cone plug, are then stored for the next batch.
To fully recover all the lead, the slag and plug are melted with extra lead and more iron. For about 15 minutes at 400c. The liquid is poured into shot and the soluble iron sulfate allowed to disolve, leaving 95%+ pure lead.


i have 3kg(maybe more) of lead in roller which left after work in roof so i dont care that much on lead. i need sulphuric acid to produce more sulph acid by contact process. everything is nearly ready , vanadium in the way and... i dont have sulphuric acid.
anyway...
You suggested me something. Ive read somewhere about way with FeSo4 but people say that better is do this decomposition with NaHSO4 because of bigger yeild. In my case to produce sodium bisulphite i need 1:1 molar ratio? Do i think good?

PbSO4 + NaOH ----> PbO + NaHSO4

khlor - 7-5-2024 at 12:30

I don' know mate, it the Sn and Fe route seems risky, how would you manage to recover the acid this way? I'd do a displacement reaction to get a soluble sulphate I could later remove the metal easily by electrolysis. Something like zinc or copper, but this talk of thermal decomposition seems to require specialized equipment a d glassware, are you sure of it? Unless I misunderstood, the goal is to recover sulphuric acid and not the lead.

bnull - 7-5-2024 at 15:33

Let me see if I got the situation right: you tried to make sulfuric acid by electrolysis of a copper sulfate solution. You added vinegar to increase conductivity, but it was way too much vinegar and, using a rather high current, you ended up with a lot of (presumably) lead sulfate. You tried to remove lead by electrolysis but, again, you used lead on both electrodes and there's even more lead sulfate than before.

Now you want to decompose lead sulfate to make SO3 and PbO so you can make sulfuric acid by the contact process. Unless you have adequate--proper, really good, not improvised--equipment, far away from other residences, I advise you against doing it. SO3 is nasty, to say the least. Not as nasty as HF, but nasty anyway.

My suggestion is that you try to remove as much lead sulfate as possible, dry it, store it in a well-labeled flask, and forget the recovery of sulfuric acid from it. Accept your losses and start with a new solution of copper sulfate (see the threads "Sulfuric acid from copper sulfate" and "Small scale production of H2SO4 in the amateur lab").

Electrolysis with lead electrodes in the presence of acetate ions is not a good idea, since lead is a cumulative poison and lead acetate is soluble. If your lead electrodes were made from the roofing material, it's possible, if not probable, that they are contaminated with arsenic, and so would be the solution.

Edit: them bloody typos again...

[Edited on 7-5-2024 by bnull]

Rainwater - 7-5-2024 at 16:39

I forgot to state the main purpose of my suggestion, lead compounds are so toxic that thermal decomposition of them is not only dangerous, its so stupid I dont even do it. ( thats a statement given i neturalized NaK with a water dropper a few weeks ago)
To avoid the danger and contamination hazard, swap out the cation to something easier to work with.
Iron sulfate is a good fertilizer (hint hint) and easy to electrolysis into H2SO4 using a clay pot (8% consentration by weight is my best results). With a professional membrane id expect higher consentrations. But if its completely unavailable in your are, here is a pathway that will not turn your lab into Mr. Hahn's backyard.
What ever pathway you take, just be safe. Molten lead produces vapors just like water. It will contaminate your entire work area, guaranteed.
lead test strips that I currently use

LookingForAnswers - 9-5-2024 at 13:32

Quote: Originally posted by bnull  
Let me see if I got the situation right: you tried to make sulfuric acid by electrolysis of a copper sulfate solution. You added vinegar to increase conductivity, but it was way too much vinegar and, using a rather high current, you ended up with a lot of (presumably) lead sulfate. You tried to remove lead by electrolysis but, again, you used lead on both electrodes and there's even more lead sulfate than before.

Now you want to decompose lead sulfate to make SO3 and PbO so you can make sulfuric acid by the contact process. Unless you have adequate--proper, really good, not improvised--equipment, far away from other residences, I advise you against doing it. SO3 is nasty, to say the least. Not as nasty as HF, but nasty anyway.

My suggestion is that you try to remove as much lead sulfate as possible, dry it, store it in a well-labeled flask, and forget the recovery of sulfuric acid from it. Accept your losses and start with a new solution of copper sulfate (see the threads "Sulfuric acid from copper sulfate" and "Small scale production of H2SO4 in the amateur lab").

Electrolysis with lead electrodes in the presence of acetate ions is not a good idea, since lead is a cumulative poison and lead acetate is soluble. If your lead electrodes were made from the roofing material, it's possible, if not probable, that they are contaminated with arsenic, and so would be the solution.

Edit: them bloody typos again...

[Edited on 7-5-2024 by bnull]

Arsenic.. mmmm... lovely. I touched it so many times without gloves. The fact is that this lead is a bit different than i had previous from angler, but i didnt take care so much because it was working as it should be. if there is no solution for the fucked up material, I will start all over again, but this time I won't choose the CuSO4 way. Thanks everyone for your help anyway :)

bnull - 9-5-2024 at 14:12

You can still use CuSO4. Just use a graphite anode; it will be attacked somewhat, but the impurities usually settle down after a while. The cathode may be of lead, there's no problem in that.

Good luck.

khlor - 10-5-2024 at 15:36

This thread is getting wild, I mean, lead, arsenic, sulphuric acid... feels lie the alchemy of old btw, what is with lead? everyone want to touch it, to use it and to have it?

back on topic. to recover the sulphuric acid from lead sulphate, I'd try to react it with zinc or some zinc salt to do a double dislacement reaction. and then electrolytically remove the zinc from the resulting zinc sulphate. other than that, I'd say your sulphuric acid is gone and your best hope is to get it from copper sulphate, epson salts like cited before on this thread and it is less dangerous than working with lead, plus, you can get decent concentrations(I got above 10% w/v, alternatively and with a little more work, you can get some porous pot(plant pot is fine) get some lye and paris paster(which is mainly calcium sulphate CaSO4, place the lye and plaster mixture with distilled water on a container with copper or stainless steel wire as cathode and inside de porous ceramic pot, place some water and place it inside the container and use a graphite rod as an anode, over time you'll get sulphuric acid, it is called electrodialysis(I think) I did some experiments a few years back, bu the yields were very low, lie 2.5% w/v measured by titration. but works.

the reaction goes like this

CaSO4(s) + 2NaOH(aq) --> Ca(OH)2(s) + Na2OH(aq) | (double displacement)
and then by electrolysis you split Na2SO4

lye is necessary in order to get the sulphate in a soluble form since CaSO4 has a negligible solubility in water.

Precipitates - 12-5-2024 at 20:12

Quote: Originally posted by khlor  
This thread is getting wild, I mean, lead, arsenic, sulphuric acid... feels lie the alchemy of old btw, what is with lead? everyone want to touch it, to use it and to have it?


It's called sciencemadness for a reason! ;)

At least we're not tasting it so that's an improvement on old alchemy!!

khlor - 13-5-2024 at 00:33

Quote: Originally posted by Precipitates  
Quote: Originally posted by khlor  
This thread is getting wild, I mean, lead, arsenic, sulphuric acid... feels lie the alchemy of old btw, what is with lead? everyone want to touch it, to use it and to have it?


It's called sciencemadness for a reason! ;)

At least we're not tasting it so that's an improvement on old alchemy!!


Fair enough of a point , I guess.