activated charcoal

[7deviations]

Has anyone made their own activated charcoal?  I started researching this subject and it does not seem prohibitively complicated.  My understanding is that you make charcoal then heat it in the absence of oxygen to create activated charcoal.  Also, you can simply use more of a lower grade activated charcoal compared to a small amount of high grade and achieve the same effect.

I have plenty of wood and basic do-it-yourself skills.  Anyone have any info on this?


-7deviations

[nustada]

I have been wondering about that too,

I am concerned about how to "clean" the charcoal, so you don't get toxins from it.

[lunk]

You need a metal tin with a screw on metal lid,
like the old style tobacco tins, a carbohydrate,
like wood or grain, and a roaring camp fire.

The object is to drive off the impurities, hydrogen and oxygen with heat,
leaving just the carbon.
 
***Do this at your own risk.*** 

Make a single small hole in the lid of the can, so the gasses can escape, and half-fill it with grain, sawdust, or blocks of wood, what ever shape you want to turn into charcoal. 

Make sure the fire is well along and has lots of glowing coals, and put the can on top of the coals so you can watch it.  Gasses should start to chimney, out of the small hole, they are flammable, make sure that they are ignited, to ensure that no oxygen can get inside the can, and start your charcoal burning
The flame, burning out from the hole, will eventually subside, and go out, quickly fish the can out of the fire and throw it into a metal bucket of cold pure water.
Let the tin cool, and open the lid, the contents should now be all turned into virtually pure activated charcoal, a little bigger, but the same shape as the organic substance you started with. 
 
...you may have to dry your charcoal if much water gets in. 

be careful as you will be dealing with heat, fire, and flammable gasses.

Charcoal blocks (made this way from hardwood) are used for testing some ore samples, as well. 

cheers, lunk




 

[nustada]

If you are thinking about it, for making it for a water filter. You can't use wood can you? doesn't most wood contain arsenic? Or can arsenic become oxidized and become harmless as well?

[lunk]

Some wood, would work,
just don't use treated or painted wood.
I think, though if you are intending
to use the charcoal for water filtration...

I would recommend starting with something edible like corn, wheat, or rice, though, and turning that into charcoal.  I have also made activated charcoal on an electric stove, but you really don't want to do this indoors, for the same reason that you don't burn a charcoal barbecue inside, as you could produce carbon-monoxide which is very toxic. 

The heat breaks apart the wood/grain carbohydrate molecule and drives off everything below the sublimation point of the carbon
leaving just and only the carbon.

Carbon also has the highest melting and sublimation point of all elements. At atmospheric pressure it has no actual melting point as its triple point is at 10 MPa (100 bar) so it sublimates above 4000 K.

http://en.wikipedia.org/wiki/Carbon

When the flame from the hole in the top of the can goes out, it's ready, but careful, the carbon will start to burn, with oxygen, and you will be left with nothing.

A simple charcoal filter can be made with a vertical length of hose, with a nail through the bottom end, to stop the charcoal chunks falling out. put a funnel at the top and drain your water, or whatever liquid, through.
You may want to add a little fine metallic silver, to prevent the growth of bacteria in your charcoal filter, if you are going to reuse it. 

Like I said in my first post,
do this at your own risk.   

cheers, lunk


 
 

[nustada]

Some wood, would work,
just don't use treated or painted wood.
I think, though if you are intending
to use the charcoal for water filtration...

I would recommend starting with something edible like corn, wheat, or rice, though, and turning that into charcoal.  I have also made activated charcoal on an electric stove, but you really don't want to do this indoors, for the same reason that you don't burn a charcoal barbecue inside, as you could produce carbon-monoxide which is very toxic. 

The heat breaks apart the wood/grain carbohydrate molecule and drives off everything below the sublimation point of the carbon
leaving just and only the carbon. http://en.wikipedia.org/wiki/Carbon

When the flame from the hole in the top of the can goes out, it's ready, but careful, the carbon will start to burn, with oxygen, and you will be left with nothing.

A simple charcoal filter can be made with a vertical length of hose, with a nail through the bottom end, to stop the charcoal chunks falling out. put a funnel at the top and drain your water, or whatever liquid, through.
You may want to add a little fine metallic silver, to prevent the growth of bacteria in your charcoal filter, if you are going to reuse it. 

Like I said in my first post,
do this at your own risk.   

cheers, lunk

Thanks a ton, you just answered a lot of questions I had.