Physisorption
When the forces of attraction are weak Vander waal forces of attraction, the process is called physisorption.
Physisorption takes place with formation of multilayer of adsorbate on adsorbent. It has low enthalpy of adsorption i.e. ∆H adsorption is 20-40 KJ/mol
It takes place at low temperature below boling point of adsorbate.
As the temperature increases, process of physisorption decreases.