What Is Adsorption--GOLD APP INSTRUMENTS

The adsorption study has quite a long history. The first document on adsorption is considered to be the study of adsorption behavior of charcoal by Fontana published in 1777. In 1814, N.T. Saussure did a lot of adsorption experiments onto charcoal. Now, his adsorption apparatus is in the exhibition of National Historical Museum in England. The adsorption technology today is widely used in the industrial process (e.g. gas and vapor separation) and characterization of fine materials.

An example of adsorption is visualizedin the figure. From the figure, it is unclear that how the chemisorptionand physisorption are different. Generally, if theinteraction between the adsorbate and adsorbent is strong (e.g. hydrogenbonding or acid-base adsorption) so that the adsorbate cannot be desorbed byvacuuming at the adsorption temperature or room temperature, it is calledchemisorption. Physisorption, on the other hand, is the weak interaction mainlydue to the van der Waals forces. The adsorbate can be easily desorbed byvacuuming. Recently, instead of using the terms “physisorption” and“chemisorption”, “reversible” and “irreversible” adsorption are also used.