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where is the mass of adsorbate adsorbed, is the mass of the adsorbent, is the pressure of adsorbate (this can be changed to concentration if investigating solution rather than gas), and and are empirical constants for each adsorbent–adsorbate pair at a given temperature.
The adsorbent, as indicated in the figure, is assumed to be an ideal solid surface composed of a series of distinct sites capable of binding the adsorbate. The adsorbate binding is treated as a chemical reaction between the adsorbate gaseous molecule A g {\displaystyle A_{\text{g}}} and an empty sorption site S .
Adsorption is the process by which a gas (or solution) phase molecule (the adsorbate) binds to solid (or liquid) surface atoms (the adsorbent). The reverse of adsorption is desorption, the adsorbate splitting from adsorbent. In a reaction facilitated by heterogeneous catalysis, the catalyst is the adsorbent and the reactants are the adsorbate.
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
An adsorption isotherm is a graph of Γ(P,T) versus partial pressure of the adsorbate(P/P 0) for a given constant temperature, where Γ(P,T) is the number of molecules adsorbed per surface area. [1] As the partial pressure of the adsorbate increases, the number of molecules per area also increases.
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.
BET model of multilayer adsorption, that is, a random distribution of sites covered by one, two, three, etc., adsorbate molecules. The concept of the theory is an extension of the Langmuir theory, which is a theory for monolayer molecular adsorption, to multilayer adsorption with the following hypotheses:
The difference is that in adsorption refrigeration, the refrigerant or adsorbate vapour molecules adsorb onto the surface of a solid instead of dissolving into a liquid. In an adsorption system, an adsorber adsorbs the refrigerant vapour into a solid, while in an absorption system, an absorber absorbs the refrigerant vapour into a liquid. [ 1 ]