Science Forums 2

[RBlack]

To Freeztar,

Charcoal adsorbs not absorbs. The difference is that ions are captured by electrostatic forces to the surface of the charcoal. Charcoal adsorbs almost everything (within reason) that it comes across. That is why charcoal is used in purifying systems for both water and air and is even given to poison victims to adsorb whatever they ingested. As far as rates and amounts I don't have that information. Also there is some difference between activated charcoal and what we make at home (see Wikipedia for definition of activate charcoal). What we make at home has about 70% carbon and the rest is impurities and this gets to your next question.

The higher the charring temperature the less impurities you get in charcoal. But it is these impurities across what is called the combustion continuum that makes charcoal in soil work. All of this is controlled by what material you char and what temperature you char it at. Everything I have read on carbon/charcoal/biochar states that there is some uncertainties in the results of all the studies. This is because of all the above variables and some studies look for "apples" in charcoal and some look for "oranges". The basic idea in making Terra Preta is to do what the Amazonian Indians did (or as close as we can come), and char up lots of different material and mix it with lots of different organic matter, put it in the soil and see what happens.

RB