Just for the fun of it I tried to extract Potassium Nitrate from black powder from fire crackers thinking it would be fairly easy as KNO3 is the only
water soluble component of black powder but even after several filtrations it still has a yellow discoloration in solution and part of the cristals
(after evaporation) schow grey /yellow coloration. Does anyone know if the manufacturers put anything besides carbon and sufur in there or do i just
need a better filter.
Also is there a better solvent for recristalisation than water?
[Edited on 11-10-2013 by Phill1337]woelen - 11-10-2013 at 00:52
Are you sure that the fire crackers are based on KNO3? They may also be based on KClO4 or KClO3. They may have stabilizers added as well, such as
dichromates (which have a yellow color at high dilution) in order to prevent unwanted oxidation of metal powder in the mix (some crackers may have
metal powders in them to for a more energetic bang).
Recrystallizing KNO3 can best be done from warm water. Solubility of KNO3 changes quite strongly when the temperature changes.Phill1337 - 11-10-2013 at 12:02
I will do a flame test the next time i can but im reasonably sure that they contain KNO3 or NaNO3 because in germany where i live this class of
firecrackers is only allowed to contain black powder. KClO3 is to instable to use in comercial firecrackers as far as i know. (plus its a health
hazard)
How could i test for dichromates / get rid of them?bfesser - 11-10-2013 at 12:12
The grayish coloration is likely due to minuscule particles of carbon. Try using a better filter.
<em>Iron</em>ically, you could try using activated carbon to remove possible colored impurities.Phill1337 - 12-10-2013 at 00:29
Quote:
Ironically, you could try using activated carbon to remove possible colored impurities.
Yea sometimes Chemistry writes its own jokes macckone - 13-10-2013 at 20:05
Temperature based recrystallization is probably your best bet. Some firecrackers also contain sugar which would carry over if you are just doing
evaporation to recrystalize.
