Activated Carbon

[gmbobnick]

Has anybody tried to make “activated carbon” from coal?

Since this really isn't about blacksmithing, I wasn't sure of the best place to post the question.  Yet, I think a blacksmith might have more of a pragmatic answer than some technical geek.

From what I understand, this of course requires a source of carbon, plus cooking things to high temps (approximately 1000 degrees F).  I understand that the process involves a phase of high heat absent of oxygen.  There are other parts of the process I don’t understand very well, but am trying to learn.

I literally have a ton of coal fines and  have recently become interested in filtering rain water to drink.  Activated carbon is useful in water treatment because of its tremendous surface area and the affinity of some contaminant chemicals for carbon.  It occurred to me that I have a source of carbon and the ability to heat things to 1000 F…so then I have at least some of the resources.  Just don’t know if the rest of the process is reasonably within reach.

Thought I would check if any blacksmith out there have messed with this at all to help flatten the learning curve.  Even if a knowledge-backed answer is “it’s not worth the trouble”, that would be helpful to me. 

 

[Frosty]

I've never heard of making it from coal but that doesn't mean anything. I've been making activated charcoal by accident for decades though. I used to shovel hot coals out of the camp fire and toss it in a bucket of water and let it dry for use. Turns out that causes steam to open pores in the charcoal "activating" it. 

When I had coal available I burned the fines the "pro" bladesmith said were worthless. I don't think he knew how or much of what he was doing. Even coal dust coked up nicely if packed around the fire wet. Not sopping wet but wet enough to pack and hold it's shape. It made really nice closed fires, not knowing better I was calling them igloo fires. 

Wish I could help with coal to activated charcoal conversion but . . . <sigh> I'll be watching though I like picking up things like that.

Frosty The Lucky. 

[Goods]

I would be worried about the elements in the coal that don’t cook of as it cokes up. I wouldn’t want to filter water with activated carbon that could contain significant levels of heavy metals.

Keep it fun,

David

[Steve Sells]

hard to make activated CHARCOAL when you arent using charcoal

[gmbobnick]

As I understand it, which may well be erroneous, one can make "char" from substances that contains carbon...wood, coconut husks...coal? 

Yeah on the heavy metals...that worries me too.

It wont take much to convince me it is better to get commercially produced activated carbon if I cant make something that is safe, even if not as effective as commercial stuff.

Having fun learning something anyway.

Thanks 

[JHCC]

1 hour ago, Steve Sells said:

hard to make activated CHARCOAL when you arent using charcoal

Activated charcoal and activated carbon are two words for the same substance, although activated charcoal is typically made from carboniferous plant matter, while activated carbon can be made from any organic substance (including coal).

[Steve Sells]

Never heard of using coal, maybe because its not very porous.  Part of making activated charcoal usable is the high surface area needed for making the chemical exchange

[Frosty]

Coal is pretty porous after it cokes but I'd rather not worry about whatever other stuff might be in it. Ever take a Geiger counter to coal? Just for an example of one kind of ingredient I think of as undesirable in my water filters.

Frosty The Lucky.

[George N. M.]

Uranium and other radioactive elements tend to preferentially bond with carbon.  That is why dinosaur bones are often "hot" to the point of not wanting to be around a large amount of them for a long period of time.

I'd want to see an analysis of any coal that I was going to use to try to make activated carbon for a drinking water filter.  Some coals csn have pretty high heavy metal concentrations.

"By hammer and hand all arts do stand."

[Frosty]

Yeah, a good Geiger counter is a good fossil hunting tool. I have some large coprolite book ends I wonder who I know who owns or has access to a Geiger counter. 

I think I'll stick with activated charcoal for things I'm going to ingest. 

Frosty The Lucky.

[Jobtiel1]

Me too. and even if you use charcoal as is it works fine for filtering without even activating it. It is a good color remover and together with other stuff to remove particles you would only need to boil the water to get good drinkable stuff. With activated you might need less but if you grind the charcoal down to a powder it works well enough.

In chemistry to separate compounds one of the most used compounds is also carbon. A chain of 18 carbon atoms with hydrogen attached bonded to a silica backbone is one of the most used separation devices for organic chemicals. 

~Jobtiel

[JHCC]

There's a lot of interesting stuff online about activated carbon made from coal, but most of it is either on commercial sites or is buried in lengthy research papers. The short version is that activated carbon is used industrially for filtering and purifying lots of different substances, not all of which are intended for direct human consumption. Activated carbon made from coal is perfectly acceptable for the latter, and because coal is already almost pure carbon, the activation process is a lot more efficient and therefore less expensive.