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.