Freundlich Adsorption Isotherms

#. Adsorption Isotherms :

It is the plot of the mass of gas adsorbed per gram of adsorbent (x / m) versus equilibrium pressure at constant temperature.

#. Freundlich Adsorption Isotherm :

It gave an empirical relationship between the quantity of gas adsorbed by unit mass of solid adsorbent and pressure at a particular temperature. It can be expressed by the equation.

                                             x / m = kp^1/n …(i)

Where, x is the mass of the gas adsorbed on mass m of the adsorbent at pressure p, k and n are constants which depend on the nature of the adsorbent and the gas at a particular temperature.

At low pressure, n = 1, i.e., x / m = kp

At high pressure, n > 1, i.e., x / m = k (independent of p)

Taking logarithm of Eq. (i)

#. Freundlich Adsorption Equation for Solutions :

x / m = kC^1/n

where, C is the equilibrium concentration. On taking logarithm of the above equation, we have