Physical adsorption
1. Forces of attraction between the adsorbent and adsorbate molecules are weak Van der Waals’ forces,
2. Heat of adsorption is low (20-40 kJ mol1)
3. It is temporary and reversible.
Chemical adsorption
1. Forces between the adsorbent and the adsorbate are strong chemical bond.
2. Heat of adsorption is high (80-24OkJ mol1)
3. It is permanent and irreversible.