24 March 2017

Difference between adsorption and absorption

Absorption is the process in which a fluid is dissolved by a liquid or a solid whereas adsorption is the process in which atoms, ions or molecules from a substance adhere to a surface of the absorbent. Let us have a deep insight into the difference between adsorption and absorption. 

Adsorption :

  • It is a phenomenon of concentration or assimilation of gas or a liquid at the surface of a solid or liquid.
  • It is a surface phenomenon.
  • It is a fast process.
  • Equilibrium is attained easily.
  • It depends upon the surface area of the adsorbent. 
  • It is an exothermic process.
  • It is favoured by low temperature.
  • It is steadily increasing and reaches equilibrium.
  • It is used in Air conditioning, water purification, synthetic resin. 
Examples : 
  • Water vapours adsorbed by silica gel.
  • NH3 is adsorbed by charcoal.

Absorption :
  • It is a phenomenon in which the substance assimilated is uniformly distributed throughout the body of the solid or liquid.
  • It is a bulk phenomenon.
  • It is a slow process.
  • Attainment of equilibrium takes some time.
  • No such effect is there.
  • It is an endothermic process.
  • It is not affected by temperature.
  • It occurs at a uniform rate.
  • It is used in cold storage, ice production, turbine inlet cooling, refrigerant. 
Examples :
  • Water vapours absorbed by anhydrous CaCl2.
  • NH3 is absorbed in water forming NH4OH.