I don't have much to contribute, but long, long ago (junior high), I
made some very nasty concentrated H2O2 out of low-grade solution. I
don't know how concentrated I got it, but it poured like syrup and
exploded in a flash of steam with a pinch of MnO2.
What I did was to pour some in aluminum pie plates and set them on top
of the forced air heating ducts for a few days or a week.
Is slow evaporation into the air a known technology for concentrating H2O2?
Keith
