Adsorption

Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) permeates or is dissolved by a liquid or solid (the absorbent). Note that adsorption is a surface-based process while absorption involves the whole volume of the material. The term sorption encompasses both processes, while desorption is the reverse of adsorption. It is a surface phenomenon.

Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent, or metallic) of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.

Adsorption is present in many natural physical, biological, and chemical systems, and is widely used in industrial applications such as activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increase storage capacity of carbide-derived carbons for tunable nanoporous carbon, and water purification. Adsorption, ion exchange, and chromatography are sorption processes in which certain adsorbates are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Lesser known, are the pharmaceutical industry applications as a means to prolong neurological exposure to specific drugs or parts thereof.

Read more about Adsorption:  Isotherms, Protein Adsorption of Biomaterials, Adsorption Chillers, Portal Site Mediated Adsorption, Adsorption Spillover, Polymer Adsorption, Adsorption in Viruses, In Popular Culture

Other articles related to "adsorption":

Langmuir Adsorption Model
... The Langmuir adsorption model is the most common model used to quantify the amount of adsorbate adsorbed on an adsorbent as a function of partial pressure or concentration at a given ... It considers adsorption of an ideal gas onto an idealized surface ... sites on the surface of the solid as indicated in Figure 1, and the adsorption process was treated as a reaction where a gas molecule reacts with an empty site, S ...
Langmuir Adsorption Model - Disadvantages of The Model
... The Langmuir adsorption model deviates significantly in many cases, primarily because it fails to account for the surface roughness of the adsorbate ... Rough inhomogeneous surfaces have multiple site-types available for adsorption, and some parameters vary from site to site, such as the heat of adsorption ... evidence for adsorbate/adsorbate interactions in heat of adsorption data ...
Supercritical Adsorption - History
... Observations of supercritical adsorption reported before 1930 was covered in studies by McBain and Britton ... During the last 20 years, a growing interest in supercritical adsorption research under the impetus of the quest for clean alternative fuels has been observed ... Considerable progress has been made in both adsorption measurement techniques and molecular simulation of adsorption on computers, rendering new insights into the nature of supercritical adsorption ...
Modifications of The Langmuir Adsorption Model - The Temkin Adsorption Isotherm
... takes into accounts of indirect adsorbate-adsorbate interactions on adsorption isotherms ... Temkin noted experimentally that heats of adsorption would more often decrease than increase with increasing coverage ... The heat of adsorption ΔHad is defined as He derived a model assuming that as the surface is loaded up with adsorbate, the heat of adsorption of all the ...
Adsorption - In Popular Culture
... have used Tetris blocks "as a proxy for molecules with a complex shape" and their "adsorption on a flat surface" for studying the thermodynamics of nanoparticles ...