Gibbs isotherm

The Gibbs adsorption isotherm for multicomponent systems is an equation used to relate the changes in concentration of a component in contact with a surface with changes in the surface tension, which results in a corresponding change in surface energy. For a binary system, the Gibbs adsorption equation in terms of surface excess is

${\displaystyle -\mathrm {d} \gamma =\Gamma _{1}\,\mathrm {d} \mu _{1}+\Gamma _{2}\,\mathrm {d} \mu _{2},}$

where

${\displaystyle \gamma }$ is the surface tension,

${\displaystyle \Gamma _{i}}$ is the surface excess concentration of component i,

${\displaystyle \mu _{i}}$ is the chemical potential of component i.