What does the Langmuir isotherm show?

June 9, 2019 Off By idswater

What does the Langmuir isotherm show?

4.2. The Langmuir adsorption isotherm is used to describe the equilibrium between adsorbate and adsorbent system, where the adsorbate adsorption is limited to one molecular layer at or before a relative pressure of unity is reached. qm is the quantity of adsorbate adsorbed in a single monolayer (mg g− 1).

What is the Langmuir adsorption constant?

The Langmuir constant (K) indicates the extent of interaction between adsorbate and the surface. If the value of K is relatively larger it indicates that there is a strong interaction between adsorbate and adsorbent while smaller value implies a weak interaction.

What is Langmuir surface area?

Langmuir surface area depends on adsorption capacity of the adsorbent. that is the volume of gas required to form monolayer is taken for calculating surface area. BET surface area is inversely proportional to the molar volume of adsorbate gas and amount of adsorbent used.

What is Langmuir?

The langmuir (symbol: L) is a unit of exposure (or dosage) to a surface (e.g. of a crystal) and is used in ultra-high vacuum (UHV) surface physics to study the adsorption of gases. It is a practical unit, and is not dimensionally homogeneous, and so is used only in this field.

What is the value of Langmuir constant?

The average values of the empirical constant and adsorption constant (saturation coefficient) for the Langmuir equation were a = 0.022 mg/g and b = 1.46 l/mg, respectively.

What is difference between surface area and specific surface area?

The total surface area is specific for the external surface, while the BET surface area is calculated with whole the surface such as surface of pores, external surface of material and calculated by the adsorption of nitrogen gas on the surface of materials.

What is the difference between the Freundlich and Langmuir adsorption isotherms?

The key difference between Freundlich and Langmuir adsorption isotherms is that Freundlich adsorption isotherm is empirical, whereas Langmuir adsorption isotherm is theoretical. The adsorption isotherm is a primary method that we can use to predict the adsorption capacity of a particular substance.

What is the difference between Langmuir and Freundlich?

The major difference between these two models is that Langmuir assumes that ions are adsorbed as a monolayer on the surface, and the maximum adsorption occurs when the surface is completely covered, whereas Freundlich has assumptions of heterogeneous surfaces with different affinities that have multilayer adsorption.

What are the three assumptions the Langmuir isotherm is based on?

The Langmuir adsorption isotherm was derived by the US chemist Irving Langmuir (1881–1957), using the kinetic theory of gases and making the assumptions that: (1) the adsorption consists entirely of a monolayer at the surface; (2) there is no interaction between molecules on different sites and each site can hold only …

What are the 2 assumptions of Langmuir isotherm?

This model is based upon the following main assumptions (Langmuir, 1916): Each active site interacts with only one adsorbate molecule. Adsorbate molecules are adsorbed on well-defined localized sites and the saturation coverage corresponds to complete occupancy of these sites.