Is it possible to "reactivate" activated charcoal once it is dirty?
Answer:
Yes, It is possible.
Physical reactivation: The precursor is developed into activated carbons using gases. This is generally done by using one or combining the following processes:
Carbonization: Material with carbon content is pyrolysed at temperatures in the range 600-900 °C, in absence of air (usually in inert atmosphere with gases like argon)
Activation/Oxidation: Raw material or carbonised material is exposed to oxidizing atmospheres (carbon dioxide, oxygen, or steam) at temperatures above 250 °C, usually in the temperature range 600-1200 °C.
Chemical activation: Impregnation with chemicals such as acids like phosphoric acid or bases like potassium hydroxide, sodium hydroxide or salts like zinc chloride, followed by carbonization at temperatures in the range 450-900 °C. It is believed that the carbonization / activation step proceeds simultaneously with the chemical activation. This technique can be problematic in some cases because, for example, zinc trace residues may remain in the end product. However, chemical activation is preferred over physical activation owing to the lower temperatures and shorter time needed for activating material.
Saturated activated carbon can be regenerated by heating.
You would take the charcoal and would wash it in a solvent and every time you do decant the dirty solvent, you can remove all of the contaminants this way. The solvent will evaporate and you are left with clean charcoal. However you must use a solvent that will not dissolve the charcoal. Either alcohol or a stronger solvent such as acetone would work well.
Dry bake the charcoal in the oven at 250 degrees Celsius. The organic contaminants will be gasified and removed thus your charcoal is activated again.
You should do a combination of what scott k and upprentice said. I would first wash the charcoal in a solvent by placing it in a Buchner funnel and washing it first with methanol then with acetone. Do this by vacuum filtration. It will be easier than decanting the solvent especially since activated charcoal floats in a lot of solvents. The only problem might be that the charcoal might pass through the funnel. If this happens decant it like scott k suggested. This will remove the organic impurities. Finally dry it in an oven at a temperature above 100 C to ensure any H2O is removed. Just drying it at 250 C will not remove the contaminants. They need to be removed by washing.
In the petroleum industry, the saturated charcoal is generally re-generated (re-activated), by passing superheated steam through it.
The steam carries the adsorbed 'nasties' out of the charcoal with it. (The superheated steam doesn't wet the charcoal).
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: