Sciencemadness Discussion Board

Potash from Charcoal Ashes

MrHomeScientist - 30-8-2019 at 11:11

I know potash can be recovered from wood ash, but can it be made from charcoal ash? Charcoal comes from wood, after all.

I have a ton of ashes from years of grilling that I was about to throw away, but thought it might be cool to try extracting potash from it. Obviously not a great way to get reagents, but could be a fun experiment.

Pumukli - 30-8-2019 at 11:44

Yes. :)
If you have lots of it as you wrote, it may worth trying.

SWIM - 30-8-2019 at 16:38

Give it a try, but be aware that yields vary greatly with the kind of wood.

Oak works great, cedar quite badly.

Some charcoal briquets are made from culm (waste coal powder and pieces), and I don't know how the potash content of that is.

Sulaiman - 30-8-2019 at 17:34

A couple of years ago I did similar ... the ashes saved from many bbq left to soak in a large bucket of water.
Some time later my wife informed me that she had helped to tidy up the area,
and cleaned out that messy bucket :(

So that's one mistake to not make :P

Alkoholvergiftung - 31-8-2019 at 00:47

Justus Liebig wrote: You can get more pottash from the plants beside the road than if you burn down an forrest for it.
Wormwood. 35-45% Pottash
Thistle. 30-35%
Sunflower 15-25%
View 15-20%.
I think oakwood ash has only 5% and needle trees below 3%.

hissingnoise - 31-8-2019 at 01:12

Indeed, potash comes from burnt green plant matter!


Carbon8 - 31-8-2019 at 11:10

Here's a partially-gated link that compares potash recovery from charcoal ash and tobacco ash:

https://pubs.acs.org/doi/10.1021/ed024p231

Here's a partially-gated link that discusses the first link:

https://pubs.acs.org/doi/10.1021/ed038pA612.3

It is also possible to titrate the potassium carbonate in ash without isolating it. Here's a gated link:

https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&am...

It might be interesting to do a video comparing the recovery of potash and soda ash from various charcoal ashes, wood ashes and seaweed ashes.

MrHomeScientist - 3-9-2019 at 06:23

Well I gave it a shot this weekend. I filled a gallon jug with 1 kg of ash and added distilled water until it was roughly halfway full. After vigorous shaking and allowing to stand for a couple days, the solution is very basic (>10). Promising!

Thanks for the links Carbon8. That would make a cool video. The first link found charcoal ash to contain 19% potash; I'll have to see how mine compares.

Fantasma4500 - 4-9-2019 at 03:53

i recall leaves were something like 3x as concentrated in potassium as regular wood, so sign yourself up for collecting leaves as weekend gig
thistle is great if you can come by it, wormwood, if you ask me is not really doable because it doesnt grow a whole lot of places, i have an idea that plants who feature some pink/purple components may contain reasonable amounts of potassium but this is pure assumption.

i recall unburnt wood soaked in water was used back in time to produce NaOH, so let it stand for a bit and you would end up with the corresponding carbonate