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In physisorption, perturbation of the electronic states of adsorbent and adsorbate is minimal. The adsorption forces include London Forces, dipole-dipole attractions, dipole-induced attraction and "hydrogen bonding." For chemisorption, changes in the electronic states may be detectable by suitable physical means, in other words, chemical bonding.
Chemisorption is a kind of adsorption which involves a chemical reaction between the surface and the adsorbate. New chemical bonds are generated at the adsorbent surface. Examples include macroscopic phenomena that can be very obvious, like corrosion [clarification needed], and subtler effects associated with heterogeneous catalysis, where the catalyst and reactants are in different pha
Adsorption is present in many natural, physical, biological and chemical systems and is widely used in industrial applications such as heterogeneous catalysts, [9] [10] activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increasing ...
Brunauer–Emmett–Teller (BET) theory aims to explain the physical adsorption of gas molecules on a solid surface and serves as the basis for an important analysis technique for the measurement of the specific surface area of materials. The observations are very often referred to as physical adsorption or physisorption.
Gas–liquid absorption (a) and liquid–solid adsorption (b) mechanism. Blue spheres are solute molecules. Sorption is a physical and chemical process by which one substance becomes attached to another. Specific cases of sorption are treated in the following articles: Absorption
Absorption is a physical or chemical phenomenon or a process in which atoms, molecules or ions enter the liquid or solid bulk phase of a material. This is a different process from adsorption, since molecules undergoing absorption are taken up by the volume, not by the surface (as in the case for adsorption).
The Langmuir model of adsorption [2] assumes . The maximum coverage is one adsorbate molecule per substrate site. Independent and equivalent adsorption sites. This model is the simplest useful approximation that still retains the dependence of the adsorption rate on the coverage, and in the simplest case, precursor states are not considered.
If a reaction occurs through these steps: A + S ⇌ AS → Products. where A is the reactant and S is an adsorption site on the surface and the respective rate constants for the adsorption, desorption and reaction are k 1, k −1 and k 2, then the global reaction rate is: