Into a beaker is put some dilute nitric acid and warm it. By means of a spatula, add red
lead a little at a time. Care must be taken not to add too much at a time or it will
contaminate the product. As the red lead is added a brown powder will ppt and lead
nitrate is formed in solution. The mixture is filtered and washed.....
The lead nitrate 'contaminant' is not a problem in our case.
Pb3O4 + 4HNO3 ~~~> PbO2 + 2H2O + 2PB(NO3)2
Another source of Lead Dioxide is an old car battery. The battery should be charged up and and all the lids removed. The battery should be inverted over a plastic or glass container to catch the sulphuric acid which can be saved for other purposes. It may have some solids suspended in it but theses will settle and you will have clear acid if you carefully pour off the clear acid into another container.
The battery is now opened using a hack saw and the plates removed. The brown powder is what you want and it will be contained in the + lead grid plates (similar to honey in bees wax, but the comparison ends there). The brown powder is removed and washed. The grey coloured stuff will be lead sulphate and spongy lead metal. There should not be much lead sulphate on the plates if the battery was well charged to start with.
Lead Dioxide is formed if between Lead electrodes a 1.5% solution of Sodium Sulphate (99.5 parts)
and Sodium Chlorate (0.5 parts) be electrolysed with a current density of 0.5 amps per dm squared.
Air should be blown through this solution and it should be acidified with sulphuric acid.
US Pat. 626330 (1899)
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