Desorptio

Desorptio, known in English as desorption, is the process by which a substance is released from a surface into the surrounding phase, such as a gas or liquid. It is the reverse of adsorption, where a material adheres to a surface. Desorptio is a key concept in surface science, catalysis, environmental engineering, and analytical chemistry.

Desorptio can be classified by the nature of the interactions that hold the adsorbate to the surface. Physical desorptio (physisorption) involves weak van der Waals forces and is typically rapid and readily reversible. Chemical desorptio (chemisorption) involves stronger chemical bonds and is usually slower and less reversible, often requiring higher energy to proceed.

Kinetics and mechanisms are often described using models developed for adsorption systems. In many cases, desorptio rates follow first-order kinetics with respect to surface coverage, particularly under Langmuir-type assumptions. Temperature, pressure, surface temperature program, and the presence of other adsorbates influence desorptio rates and energy barriers. Temperature-programmed desorption (TPD) is a common experimental technique used to characterize desorptio, revealing desorption energies and the distribution of binding sites.

Measurement and techniques used to study desorptio include mass spectrometry to monitor desorbed species, quartz crystal microbalance for mass changes on a surface, infrared spectroscopy for identifying desorbed species, and surface probes that track changes in adsorption sites during desorption cycles.

Applications of desorptio include catalyst regeneration, where adsorbed poisons or products are removed to restore activity; environmental remediation, where contaminants desorb from soils or sorbents; and analytical separations, such as desorption steps in solid-phase extraction and chromatography.