Physical Adsorption or Physisorption: When the force of
attraction existing between adsorbate and adsorbent are weak Vanderwaal
forces of attraction, the process is called Physical Adsorption or
Physisorption. Physical Adsorption takes place with formation of multilayer
of adsorbate on adsorbent. It has low enthalpy of adsorption i.e. H
adsorption is 20-40KJ/mol. takes place at low temperature below boiling
point of adsorbate. As the temperature increases in, process of Physisorption
decreases.