Langmuir, Irving isotherms

Langley, John Newport, 2-3, 3f Langmuir, Irving, 10, 12f Langmuir adsorption isotherm... 

This model of adsorption was suggested by Irving Langmuir and is referred to as the Langmuir adsorption isotherm . The aim of this experiment is to test the validity of this isotherm equation and to measure the surface area per gram of charcoal, which can easily be obtained from the measured value, if the area per solute molecule is known. 

The Langmuir adsorption isotherm was developed by Irving Langmuir in 1916 from kinetic considerations to describe the dependence of the surface fractional coverage of an adsorbed gas on the pressure of the same gas above the adsorbent surface at a constant temperature. The Langmuir isotherm expression was re-derived thermodynamically by Volmer and statistically mechanically by Fowler. In his original treatment, Langmuir made several assumptions for his model ... 

It is convenient to have an equation relating the amount of substance attached to the surface, or adsorbed, to the concentration of the substance present in the gas phase or in solution. Such equations apply at a fixed temperature, and are known as adsorption isotherms. The simplest adsorption isotherm was first obtained by the American physical chemist Irving Langmuir (1881-1957), The basis of the derivation of the Langmuir adsorption isotherm is that all parts of the surface behave in exactly the same way as far as adsorption is concerned. Suppose that, after equilibrium is established, a fraction 0 of the surface is covered by adsorbed molecules ... 

The Langmuir isotherm best describes the chemisorption process. Irving Langmuir was awarded the Nobel Prize in 1932 for his invesfigafions concerning surface chemistry. Langmuir s isotherm describing the adsorption of adsorbate (A) onto the surface of the adsorbent (S) is based on three assumptions ... 

There are several theoretical derivations of adsorption isotherms. The simple Langmuir equation [Eq. (4.2), named after the American chemist and 1932 Nobel laureate Irving Langmuir], describes the formation of a monolayer on a surface [81]. This corresponds to the type I isotherm shown in Figure 4.15. Here Vis the amount adsorbed, Vm is the amount adsorbed in one monolayer, p is the pressure and b is the adsorption coefficient, which depends exponentially on the heat of adsorption. 

By means of molecular-kinetic arguments, Irving Langmuir [24,25] developed an adsorption equation, which describes very well the shape of type I isotherms (see Figure 4.1), even though this equation was initially developed for an open surface (nonporous solid). The starting point is the dynamic concept of the adsorption equilibrium in which the rates of adsorption and desorption are equal. Other assumptions were made ... 

The Langmuir isotherm, regarded as the starting point for any discussion of isotherms because of its simplicity and applicability, was derived by Irving Langmuir in 1918. Langmuir made four assumptions ... 

Henry and Freundlich isotherms did not provide for C. value growth limit. Irving Langmuir (1881-1957) in 1916 introduced such limit C and proposed a more complex but more accurate equation. He viewed the adsorption balance as a result of the competition between the rates of adsorption and desorption. If maximum adsorbent capacity relative component i is j> it may be assumed that the adsorption rate is proportion-... 

Equation A2-5 is called the Langmuir Equation (also known as the Langmuir Isotherm, or Langmuir Adsorption Equation), being published by Irving Langmuir in 1916. 

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