Final answer:
Activated charcoal primarily works via adsorption, where contaminants adhere to its surface. It is used for water purification and to treat poisonings.
Step-by-step explanation:
The majority of carbon dioxide in the blood is transported as bicarbonate ions, although a small percentage binds to hemoglobin or dissolves directly in the blood plasma. The primary process for activated charcoal to work is through adsorption, where substances adhere to its large surface area. Adsorption is sometimes confused with absorption, but in the context of activated charcoal, it is the surface phenomenon that plays the crucial role in its effectiveness for removing contaminants from water or for medical applications such as treating poisonings and overdoses.