На AROCKET опять обсуждают перегонку перекиси.
There's more danger to boiling off peroxide than a vapor detonation. If you start out with less than food grade quality material, say "technical" or "standard" grade, you may make a solution rich in carbon content - dangerously so. "Dangerously so" = 1 to 2% by weight, depending on the HTP concentration.
FMC had a detonation quite a few years ago in a distillation column making 70%. While the column was surrounded by reinforced concrete, the detonation wave passed through the concrete and reformed itself into the "safe" zone - destroying pumps in the process. The problem was not continually pumping out the concentrated peroxide and allowing the carbon content to reach dangerous levels.
Remote open air boiling is the cheapest and simplest method to concentrate stabilized 50 % if your intention is to produce only a few gallons/week of a stabilized HTP product for propulsion evaluation tests. All it requires is a glass 5-10 L Erlenmyer a vapor guide, a remotely operated butane burner, a safe field location and, unless you have an automatic boiling temperature controlled butane valve: lots of time. The method was recommended in peroxide propulsion papers by specialists dr. A. Musker, a research fellow of Southampton university and dr. John Rusek and coworkers of Purdue university to name a few who have prepared many gallons of HTP that way:
http://www.gkllc.com/lit/...
http://www.dtic.mil/cgi-bin/...
It is also the safest method. Why? because it is a
remote operation (in the field only, not in a garage, attic or do it yourself lab) so even a rare detonation is never a problem. For a rocketeer a hard start with shrapnel is safe because similarly, it is a remote operation. Other peroxide lab enrichment methods such as vacuum evaporation/distillation, crystallisation or sparging are not 100 % safe because they are indoors, more complicated and require your presence which
can expose people to concentrated vapors or a detonation if things, however unlikely, do go out of control.
Prepare HTP outside and operate remotely, never near living quarters is a good safety motto.
If you require rocket grade HTP because you need silver screen decomposition and can accept no stabilisers it may be preferable to order it from PeroxidePropulsion in Sweden (or from XL-Space if you’re living in the US?). But sooner or later this option may no longer exist.
As to start evaporation using the Solvay Ultrapure 50 % quality which John C. once recommended: I have still been unable to obtain that product in Europe so far. I have the impression it is not produced over here.