What do you understand by activation of adsorbent? How is it achieved?

Activation of adsorbent means increasing the adsorbing power of an adsorbent.
This can be done by increasing the surface area of the adsorbent, which can be achieved by any of the following ways:
(i) By removing the gases adsorbed, e.g. wood charcoal can be activated by heating it between 600 °C and 1200 °C in vacuum or in superheated steam.
(ii) By breaking the adsorbent into small pieces.
(iii) By making the surface of adsorbent rough.