The SEM micrographs of the samples are given in Fig. 2. The external
surfaces of these oxidized activated carbons showed the presence of
cavities, and were more or less homogeneous. These cavities differ
from one sample to another, by the reaction of the oxidizing agent on
the surface of activated carbon. Fine particles attached to the surface
of the Nebka seed activated carbon are probably impurities introduced
during the preparation, such as particles of salts formed during activation,
but may be also be due to the vegetable origin of the carbon [19].