physisorptioonis

Physisorption is a type of adsorption that involves the physical binding of molecules to the surface of a material. Unlike chemisorption, which involves a chemical bond between the adsorbate and the adsorbent, physisorption is a reversible process.

In physisorption, the molecules adsorbed to the surface of the material do not undergo any chemical change. Instead, they interact with the surface through weak intermolecular forces, such as van der Waals forces. These forces are responsible for holding the molecules in place, but they are easily broken, allowing the molecules to be easily desorbed from the surface.

Physisorption is commonly observed in systems where the surface of the material is non-polar or has a low electron density. For example, in the adsorption of noble gases on non-polar surfaces. Other types of molecules, such as water and organic compounds, can also undergo physisorption on hydrophobic surfaces.

The isotherm of physisorption is typically characterized by a Type II or Type III shape, indicating a gradual increase in the amount of gas adsorbed as the pressure increases. The Langmuir equation can be used to model the physisorption isotherm, but it often requires modifications to account for the weak intermolecular forces involved.

Physisorption is an important phenomenon in various fields, including catalysis, in which control of physisorption can affect the activity of the catalyst. It is also observed in the allocation and removal of volatile organic compounds from wastewater streams.