Sciencemadness Discussion Board

Lead Sulfate to Sulfuric Acid

Chemistrium - 9-4-2013 at 19:20

Okay, so I was just wondering (I've already used the search tool and such) if lead sulfate could be an alternate production method for sulfuric acid (as used in lead acid car batteries). So if I were to preform an electrolysis of lead sulfate in a suspension (due to its low solubility in water) of water, it should lead to this:

On the cathode:
PbSO4 + H+ + 2e- --> HSO4- + Pb

On the anode:
PbSO4 + H2O --> HSO4- + PbO2 + 3H+ + 2e-

So it eventually leads to this:
2PbSO4 + 2H2O --> 2H2SO4 + PbO2 + Pb

Any suggestions and other things that may help?
Also if done carefully, the lead dioxide may be plated onto the anode...

[Edited on 10-4-2013 by Chemistrium]

MrHomeScientist - 10-4-2013 at 06:15

I am not an expert with electrolysis, but I think I know enough to talk to this. I am fairly certain this would do nothing. Electrolysis requires dissolved ions - negative ions are attracted to the anode and drop off their electrons while positive ions go towards the cathode to pick up electrons. If you have a suspension of a neutral solid, it isn't attracted to either pole and would just float around doing nothing. This setup would likely just break up water into H2 and O2.

Fantasma4500 - 10-4-2013 at 06:55

both H2SO4 and PbO2 coating, that would be interesting, but IIRC lead salts solubility is pretty much around the same as barium salts, meaning nearly insoluble sulfate salt, right?
i guess it would be a very slow reaction, but on the other hand H2SO4 doesnt decompose like that..
if one had a decent source of PbSO4 this could be a good idea for getting several things..
tbh i havent really heard of PbSO4 for any actual use, probably because its toxic and nearly completely insoluble (0.003836 @ 20*C 100 mL)
lead isnt very reactive if at all towards H2SO4, guess it would be like buying aluminium nitrate aswell..
so considering leads not so good reactivity with H2SO4 if even possible at all other than double displacement reactions yielding PbSO4, where would you get it? doesnt sound very profitable tbh (:

woelen - 10-4-2013 at 06:55

This indeed will not work. Electrolysis does not work with suspended solids. You need ions in solution.

An interesting thing though is that neutral molecules may be affected in the electrolysis process. E.g. electrolysis of a solution of ethanol in dilute H2SO4 leads to formation of ethanal or even acetic acid at the anode. The area around the anode becomes strongly oxidizing and this leads to oxidation of the ethanol.

Even stronger, positive ions may be oxidized at the anode or negative ions may be reduced at the cathode. E.g. electrolysis of a solution of Na2SO3 leads to formation of sulphur at the cathode (besides hydrogen), even though the SO3(2-) ions are negatively charged and are repelled by the cathode.

This type of redox reactions, however, only occurs on dissolved species, not on solid particles, floating around in the liquid.

This might help

franklyn - 10-4-2013 at 06:58

www.sciencemadness.org/talk/viewthread.php?tid=22860#pid2698...

Adas - 10-4-2013 at 08:22

Is it possible to melt the PbSO4? If yes, it would be the one way to go.

papaya - 10-4-2013 at 11:21

Remember how lead acid battery discharges? It'll form PbSO4 on both terminals, and if this battery is capable of recharging, then this is more than possible! You don't need a suspension, I think if you take a lead plate large enough and can spread on it wet PbSO4 to stick, then using this plate as a cathode ,metalic lead will be recovered and sulfuric also will be generated. I know this from an accident, when during one electrolysis experiment it happened for cathode to touch underlaying PbSO4 deposition - lead dust started to form at this point and because it is conductive it started to spread forward, I believe whole powder, though not compactm could be converted to lead.

elementcollector1 - 10-4-2013 at 11:23

Quote: Originally posted by woelen  
... E.g. electrolysis of a solution of Na2SO3 leads to formation of sulphur at the cathode ...

Good to know!

Chemistrium - 10-4-2013 at 14:01

Quote: Originally posted by Antiswat  

i guess it would be a very slow reaction, but on the other hand H2SO4 doesnt decompose like that..
if one had a decent source of PbSO4 this could be a good idea for getting several things..
tbh i havent really heard of PbSO4 for any actual use, probably because its toxic and nearly completely insoluble (0.003836 @ 20*C 100 mL)


So do you mean this?:

Cathode:
PbSO4 + 2e- --> SO4-2 + Pb

Anode:
PbSO4 + 2H2O --> SO4-2 + PbO2 + 4H+ + 2e-

I think it would go either way...

...Its solubility is low... but maybe this could work (making the lead sulfate have direct contact with the anode and cathode...):
Quote: Originally posted by papaya  
Remember how lead acid battery discharges? It'll form PbSO4 on both terminals, and if this battery is capable of recharging, then this is more than possible! You don't need a suspension, I think if you take a lead plate large enough and can spread on it wet PbSO4 to stick, then using this plate as a cathode ,metalic lead will be recovered and sulfuric also will be generated.


I almost forgot about that part of the battery.

Fluorite - 22-12-2020 at 14:16

Maybe you can bubble hydrogen sulfide and make sulfuric acid + lead sulfide

TriiodideFrog - 22-12-2020 at 21:11

I know electrolysis of copper sulfate gives you sulfuric acid and copper. Not sure about lead sulfide though.