PHYSISORPTION Meaning and
Definition
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Physisorption, also known as physical adsorption, is a process in which molecules or atoms are attracted and held onto the surface of a solid material through weak van der Waals forces or London dispersion forces. It is a type of adsorption that occurs at relatively low temperatures and pressures.
In physisorption, the molecules or atoms are not chemically bonded to the surface of the material but are rather attracted to the surface due to the weak forces of attraction between their electron clouds and the electron clouds of the material's surface. These forces arise from temporary fluctuations in electron density, which create temporary dipoles and induce dipoles. As a result, the adsorbed species can easily be desorbed from the surface by reducing the pressure or increasing the temperature.
Physisorption plays a significant role in various chemical and physical processes, including gas storage, catalysis, separation techniques, and surface science research. It often occurs on porous materials, such as activated carbon or zeolites, which have a large surface area and abundant surface sites for adsorption.
The study of physisorption is crucial for understanding the behavior of gases and liquids on solid surfaces, as well as for designing efficient adsorbents and catalysts. Various techniques, such as gas adsorption isotherms, surface area measurements, and spectroscopic methods, are employed to characterize and quantify physisorption phenomena.
Etymology of PHYSISORPTION
The word "physisorption" is derived from two Greek roots: "physis" meaning "nature" or "natural" and "sorption" meaning "absorption" or "adhesion". The term "physisorption" is used to describe a type of adsorption in which molecules adhere to a solid surface through relatively weak intermolecular forces or Van der Waals interactions.
