[VanMarco]

hello there, I am new, nice to meet you all!
I have been working on a project, which is, making new battery paste(S) for making new storage batteries.
I have been following this paper https://www.scientificbulletin.upb.ro/rev_docs_arhiva/full076_489166.pdf
In short, the paper talks about dissolution of lead pastes from waste batteries in NaOH solution and the recovery
via electrolysis.
The paper speaks of lead solubilization in various NaOH solutions, the best being 6M / 60C / 2Hrs. which is what I used.
I ran 2 batches.
Batch #1 I dissolved PbO2+PbSO4 from a positive plate of a waste battery. some of it dissolved
and i think most of the PbSO4 went into solution as Pb(OH)2 and NaSO4.
(I did not find any information on the web about solubility in NaOH of different lead salts). The remaining PbO2
looks a lot more red, than brown. the solution was then electrolyzed with lead anode, and copper cathode.
If i am right and as i suspect lead sulphate is a lot more soluble than lead dioxide, this paste could be re-used as is.

Batch #2 Dissolved the spongy lead from the negative plate. a LOT of lead went into solution, and was also retrieved
by the same manner as above. during this process, something happened. the bottom of the beaker, started lining up
with PbO2.
I think this formed due to oxygen being bubbled from the anode.

My question is this. Is it possible that bubbling air for long periods of time into a solution rich in lead hydroxide, yield PbO2?

I have some pictures here https://imgur.com/a/0Z7vWZK (I know you are against hyperlinking, but they are big images. Shown = spongy lead and cell).
the solution looks blueish likely due to copper that dissolved from the cathode, presence of NaSO4 makes it soluble.

Thank you so much