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The Freundlich equation or Freundlich adsorption isotherm, an adsorption isotherm, is an empirical relationship between the quantity of a gas adsorbed into a solid surface and the gas pressure. The same relationship is also applicable for the concentration of a solute adsorbed onto the surface of a solid and the concentration of the solute in ...
The Freundlich isotherm is the most important multi-site adsorption isotherm for rough surfaces. =, where α F and C F are fitting parameters. [14] This equation implies that if one makes a log–log plot of adsorption data, the data will fit a straight line. The Freundlich isotherm has two parameters, while Langmuir's equations has only one ...
The Langmuir isotherm is given by: [CS] = (K eq S tot [C])/(1 + K eq [C]), where S tot is the total binding molecules on the beads. The Freundlich isotherm is given by: [CS] = K eq [C] 1/n. The Freundlich isotherm is used when the column can bind to many different samples in the solution that needs to be purified.
The model applies to gases adsorbed on solid surfaces. It is a semi-empirical isotherm with a kinetic basis and was derived based on statistical thermodynamics. It is the most common isotherm equation to use due to its simplicity and its ability to fit a variety of adsorption data. It is based on four assumptions:
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:
English: An isotherm according to the Freundlich equation with K=1 and n=3. Deutsch: Adsorptionsisotherme nach Freundlich mit K=1 und n=3. Date: 27 December 2016:
The theory has been used to model the adsorption of carbon nanotubes and carbon nanoparticles. In the study done by Yang and Xing, [6] the theory have been shown to better fit the adsorption isotherm than Langmuir, Freundlich, and partition. The experiment studied the adsorption of organic molecules on carbon nanoparticles and carbon nanotubes.
This may be written in the following form, known as the Ostwald–Freundlich equation: =, where is the actual vapour pressure, is the saturated vapour pressure when the surface is flat, is the liquid/vapor surface tension, is the molar volume of the liquid, is the universal gas constant, is the radius of the droplet, and is temperature.