Question

What is adsorption isotherm? Describe freundlich adsorption isotherm.

Answer 1

Hint :Adsorption isotherms have played a critical role in studies of environmental protection and adsorption methods. The Freundlich and Langmuir isotherms are two of the most used approaches for estimating a material's adsorption capacity.

Complete Step By Step Answer:
The adherence of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface is known as adsorption. This procedure forms an adsorbate layer on the adsorbent's surface. This contrasts from absorption, which occurs when a fluid (the ascorbate) dissolves or penetrates a liquid or solid (the absorbent). Adsorption is a surface process, whereas absorption affects the entire volume of the substance, however adsorption frequently occurs before absorption. Both processes are referred to as sorption, whereas desorption is the opposite.
The Freundlich adsorption isotherm is a mathematical connection between the amount of gas adsorbed on a solid surface and the gas pressure. The concentration of a solute adsorbed onto the surface of a solid and the concentration of the solute in the liquid phase have the same relationship. Herbert Freundlich proposed an equation for the isothermal variation of adsorption of a quantity of gas adsorbed by unit mass of solid adsorbent as a function of gas pressure in 1909. Because this connection is completely empirical, it is typically preferable to employ isotherms with a theoretical basis when adsorption behaviour can be well fit by them.
It is given as
 ${\displaystyle \frac{x}{m}}=K{p}^{1/n}$
It is also written as
 $\log {\displaystyle \frac{x}{m}}=\log K+{\displaystyle \frac{1}{n}}\log p$
Or
 ${\displaystyle \frac{x}{m}}=K{c}^{1/n}$
It is also written as
 $\log {\displaystyle \frac{x}{m}}=\log K+{\displaystyle \frac{1}{n}}\log c$ .

Note :
The Freundlich equation may also be obtained (non-empirically) by attributing changes in the binding process' equilibrium constant to surface heterogeneity and adsorption heat fluctuation. At greater pressures, the Freundlich adsorption isotherm also fails.