is based on the assumption that adsorption occurs at
speci c homogenous sites within the adsorbent. It explains
monolayer adsorption which lies on the fact that the adsorbent
has a nite capacity for the adsorbate i.e. at equilibrium; a sat-
uration point is attained where no further adsorption can oc-
cur. The equation below shows the Langmuir isotherm
expressions: