4.1.3. Hydrogenated groups

Hydrogen atoms are usually present in the surface of activated carbons such as chemisorbed water, as part of other surface groups such as carboxylic acids, phenols, amines, or even directly attached to carbon atoms as part of aromatic or aliphatic structures.

#### 4.1.4. Phosphorus groups

Phosphorus atoms contained in activated carbons generally come from the phosphoric acid used as an activating agent in the preparation stage. Once phosphorus is located in the carbon matrix, it can be stable between 500 and 1000C; this atom can be found as red phosphorus or chemically bonded as dCdPd or dCdOdPd. Phosphorus-containing species can be formed during carbonization at low temperature ranges [16].
