Update: The crystals that formed from the evaporated anolyte are highly impure as evidenced by the presence of white crystals and brown crud among the
needles of KMnO4. The crystals were dissolved in a small amount of water and the solution was heated up to boiling. It was filtered while hot on a
preheated filter funnel (to remove MnO2, again). The filtrate yielded 0.37 g of small (and pure) needles of KMnO4 upon cooling.
(More KMnO4 could be extracted from the anolyte, but this run was just to prove that the method works and I didn't try to be particularly efficient in
the extraction.)
The product was tested by adding a few drops of conc. H2SO4 to a crystal to form Mn2O7 and the reaction with ethanol was as expected: it ignited!
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