Füüsiksorptsioon

Füüsiksorptsioon, often shortened to physisorption, is a type of adsorption where the adsorbate molecules are held to the adsorbent surface by weak van der Waals forces. Unlike chemisorption, which involves the formation of chemical bonds, physisorption is a reversible process characterized by low enthalpy of adsorption, typically in the range of 20-40 kJ/mol. This low energy release indicates that no significant electronic rearrangement occurs at the interface.

The phenomenon is driven by intermolecular attractions, such as dipole-dipole interactions, London dispersion forces, and induced dipole interactions. Physisorption is not specific to particular chemical bonds and can occur between any gas and solid surface at sufficiently low temperatures. The extent of physisorption is highly dependent on temperature and pressure. At low temperatures and high pressures, the adsorbate molecules have reduced kinetic energy and a higher probability of being captured by the adsorbent surface.

Physisorption is crucial in various scientific and industrial applications. It is the primary mechanism in gas storage, where materials like zeolites or activated carbon adsorb gases under pressure. It also plays a role in chromatography, where the separation of compounds is based on their differential physisorption onto a stationary phase. Furthermore, physisorption is fundamental to understanding the behavior of gases in porous materials and is a key consideration in areas like catalysis and membrane separation. The reversibility of physisorption allows for easy regeneration of adsorbents, making it an economically viable process.