Thread: Synthesis of Activated Charcoal.

Dear All,

I am working on a thesis dealing with the desalination and purification of waste water. During the process a need has arised for the sysnthesis of Activated Charcoal. I request you to kindly send me the paper(s) dealing with the preparation process or guide me to such a source so that I am ablt to manufacture it in my lab. I will be grateful.

Regards,

Atta.

Wow, this one is a sleeper! I imagine that Atta has moved along from this need, but it is kind of fun dragging up these old unanswered questions.

Hello Atta,

I don't think that making activated charcoal in the laboratory is a good prospect. And it is readily available from various sources.

One method of making activated carbon industrially by the action of carbon dioxide or water vapour on some form of carbon from another source, at high temperature. This can be coal char, wood char, or very commonly coconut char. The mode of attack of the carbon dioxide or steam is to remove the carbon in such a way that the remaining material is in sheets. The surface area of these sheets can be very large. I forget what the theoretical maximum is now, but IIRC it is above 2000 m2 per gram. Typically, commercial activated carbon has a surface area of more than 1000 m2 per gram.

Within the activated carbon, there will be pore size distribution. This will mainly be a reflection of the source carbon. The pore structure and sizing will affect the absorption properties of the activated carbon. Larger pores allow access to larger molecules.

The surface area of activated carbon is most simply measured by the adsorption of iodine from an aqueous solution using a titration method using starch. Charcoal from your fireplace will give a zero reading by this method as the surface area per gram is extremely low. Charcoal that has been prepared under reducing conditions will give a higher surface area. So you could prepare activated carbon in the laboratory by heating up charcoal with, say iron oxide in a closed crucible. But it would be hard work and you would need to be able to verify your result by titration.

Another method of surface area determination is by helium adsorption, but that requires access to more sophisticated equipment.

Large quantities of activated carbon are made from coconut char. The char is made in simple kilns on a local basis and then the char is activated in large rotary kilns in a centralised location. A lot of this material gets used in the gold industry. It has the advantage of high strength, because the char shrinks as it is processed, so that the end density is increased. Other activated carbon is a by-product of the manufacture of titanium dioxide from ilmenite. In this case the source of carbon is coal.

That's probably enough for now.

Originally Posted by Warron

Wow, this one is a sleeper! I imagine that Atta has moved along from this need, but it is kind of fun dragging up these old unanswered questions.

But easy does it, thread necromanacy is frowned upon by some of the mods...

Originally Posted by PhDemon

Originally Posted by Warron

Wow, this one is a sleeper! I imagine that Atta has moved along from this need, but it is kind of fun dragging up these old unanswered questions.

But easy does it, thread necromanacy is frowned upon by some of the mods...

Oh, really?

What a shame. The forum is littered with unanswered questions and there are not enough new ones to foster a community.

I can't seem to edit my post, but of course it should be adsorption.

Originally Posted by Warron

Originally Posted by PhDemon

Originally Posted by Warron

Wow, this one is a sleeper! I imagine that Atta has moved along from this need, but it is kind of fun dragging up these old unanswered questions.

But easy does it, thread necromanacy is frowned upon by some of the mods...

Oh, really?

What a shame. The forum is littered with unanswered questions and there are not enough new ones to foster a community.

This mod doesn't have a problem with it, especially when some useful information is provided by a knowledgeable contributor.

Fair enough but I've seen posts where a mod has specifically asked people not to do it and was just giving a heads up about it to a relatively new member.

Originally Posted by PhDemon

Fair enough but I've seen posts where a mod has specifically asked people not to do it and was just giving a heads up about it to a relatively new member.

Thanks for the heads up in any case. If nobody says anything you can blunder around blissfully unaware.

And thanks to Harold for his comment I haven't mastered multiple quotes yet.

I'm sorry I am still not clear about just what one does to charcoal to make it "activated". I'm not sure what "activated" means in this context. I'm visualizing "non- activated" charcoal as a briquette in the bag and "activated" charcoal as the same lump having been thrown across the room. Clearly this is not correct but specificly how and why is it incorrect?

Originally Posted by Sealeaf

I'm sorry I am still not clear about just what one does to charcoal to make it "activated". I'm not sure what "activated" means in this context. I'm visualizing "non- activated" charcoal as a briquette in the bag and "activated" charcoal as the same lump having been thrown across the room. Clearly this is not correct but specificly how and why is it incorrect?

Activated implies that it is capable of adsorbing molecules of various types.

To do this, it must have an extended surface area.

Normal charcoal does not have an extended surface area, so the process of activation is the process of creating an extended surface area within the charcoal.

This is done removing some of the carbon atoms by reaction with carbon dioxide or steam.

C+CO2 -> 2CO or C+H2O ->H2 + CO

These gases remove the carbon in such a way that the remaining material comprises sheets of carbon, which have an extended surface area. Imagine removing every second page in a book.

Does this explanation help?