Amongst all the wonderful ways that activated charcoal can be used, it’s place for filtering water, is one of its most useful and irreplaceable roles.
When living off grid, having a clean source of consumable water, is not just a luxury. Unless you have a natural spring as a water source, you will need a way of filtering the water you collect, regardless of its source. Even with a natural spring, it’s a good idea to filter.
If your project is directed at ultimately making a cheap water or air filter for off grid circumstances, it should be noted that plain charcoal has a long history of use in odor control and water purification.
As far back as 1500 B.C. down to hospitals in the 1800s, plain charcoal powder was used to control the stench of rotting flesh. Ancient sea explorers scortched the inside of wooden water barrels to preserve drinking water during long voyages. The American Calvary used plain lump charcoal in the last compartment of a 3-compartment box to filter swamp water, to make it drinkable.
It has been found that even the plain wood charcoal has fragments of the super molecule (C60) that has phenomenal adsorptive capacities.
So, if it is for some rough or makeshift circumstances, just your regular charcoal will work effectively enough as both a water and air filter, and without the potential mishaps of trying to activate it with some potentially dangerous and corrosive chemicals.
I have found in my research that “activated” charcoal, varies only in the amount of micro pores which are embedded into each fragment of the coal.
Chemically speaking, activated coal is the same as plain coal. The pits, or pores in the surface of activated coal, give it a much larger surface area than the same amount of “regular” coal. It’s this increase in surface area that gives the activated coal it’s ability to be such an excellent filter. Calculations have shown that some industrial produced activated coal, has a surface area of up to 25 acres per pound! The pores are some times filled with other material, for different purposes. Silver is mixed into the carbon pores in order to filter contaminants like mercury and organic arsenic from water. When this is done, the carbon is referred to as impregnated carbon.
Here is a very easy to follow article on making your own activated charcoal.
It also describes several different types of materials that you can use in making the coal before you do the activation process. And descriptions as to why you should use one over another: http://www.buzzle.com/articles/how-to-make-activated-charcoal.html Remember, you can avoid the chemicals, and just crush, and use the coal that is produced from the coal cooking process.
There is another method for the activating process.
It doesn’t involve using potentially dangerous chemicals. In fact it uses steam, and high temperatures to create the pores. However, the temperatures are higher (1000°plus) than most are able to create, without specialized equipment. For this reason, I won’t be giving a detailed breakdown of the process. It can be found easily enough, if one is interested in reading about it.