How does functionalized activated charcoal work?
No. It is not a precipitation reaction. It is physical reaction. The pores are made of the rest of the membranes of the cells. When wood is overheated in air, it burns. When this is done without too much contact with the air, the cellular water gets evaporated. The content of the cell (cytoplasm, proteins, etc.) is pyrolyzed, destroyed and mostly transformed into gases. The membrane is carbonized or charred, but remains here, forming charcoal. The rest of the cell being eliminated, the charcoal contains a huge amount of the previous cells which behave like pores. Big molecules can enter these shells, and have difficulty to get out later on.